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Research Article
Revision of the genus-group Hystricella R. T. Lowe, 1855 from Porto Santo (Madeira Archipelago), with descriptions of new recent and fossil taxa (Gastropoda, Helicoidea, Geomitridae)
expand article infoWilly De Mattia§, Marco T. Neiber|, Klaus Groh
‡ Natural History Museum Vienna, Vienna, Austria
§ International Centre for Genetic Engineering and Biotechnology, Trieste, Italy
| University of Hamburg, Hamburg, Germany
¶ Unaffiliated, Bad Dürkheim, Germany
Open Access

Abstract

The genus-group Hystricella R. T. Lowe, 1855 is revised on the basis of conchological, anatomical and genetic characteristics. A new genus Wollastonia gen. n., two recent species, W. jessicae sp. n. and W. klausgrohi sp. n., and one recent subspecies, W. jessicae monticola ssp. n. are described as new to science, as well as five fossil taxa, H. microcarinata sp. n., W. beckmanni sp. n., W. falknerorum sp. n., W. ripkeni sp. n., and W. inexpectata sp. n. For Helix vermetiformis R. T. Lowe, 1855, H. leacockiana Wollaston, 1878, H. oxytropis R. T. Lowe, 1831, H. duplicata R. T. Lowe, 1831 and H. oxytropis var. ß subcarinulata Wollaston, 1878 lectotypes are designated. For the taxa Helix bicarinata G. B. Sowerby I, 1824, Helix bicarinata var. ß aucta Wollaston, 1878 and Discula bulverii W. Wood, 1828 neotypes are selected. The taxa aucta and subcarinulata are elevated to specific rank. For the hitherto monospecific (sub-) genus Callina R. T. Lowe, 1855 it is shown that it is not closely related to the genus Discula but to the Hystricella-group and its generic rank is confirmed. The taxon D. bulverii W. Wood, 1828 is transferred from the genus Discula s. str. to the genus Callina. A further fossil taxon C. waldeni sp. n. is described as new to science.

Kurzfassung

Die Gattungsgruppe Hystricella R. T. Lowe, 1855 wird anhand von conchologischen, anatomischen und genetischen Merkmalen revidiert. Eine neue Gattung Wollastonia gen. n., zwei rezente Arten, W. jessicae sp. n. und W. klausgrohi sp. n. sowie eine rezente Unterart, W. jessicae monticola ssp. n., werden neu beschrieben, wie auch fünf fossile Taxa, H. microcarinata sp. n., W. beckmanni sp. n., W. falknerorum sp. n., W. ripkeni sp. n., und W. inexpectata sp. n. Für Helix vermetiformis R. T. Lowe, 1855, H. leacockiana Wollaston, 1878, H. oxytropis R. T. Lowe, 1831, H. duplicata R. T. Lowe, 1831 und H. oxytropis var. ß subcarinulata Wollaston, 1878 werden Lectotypen designiert, für die Taxa Helix bicarinata G. B. Sowerby I, 1821, Helix bicarinata var. ß aucta Wollaston, 1878 und Discula bulverii W. Wood, 1828 Neotypen festgelegt. Die Taxa aucta und subcarinulata werden in einen spezifischen Rang erhoben. Es wird gezeigt, dass die bisher monospezifische (Unter-) Gattung Callina R. T. Lowe, 1855 nicht mit der Gattung Discula, sondern mit der Hystricella-Gruppe näher verwandt ist und im Gattungsrang bestätigt. Das Taxon D. bulverii W. Wood, 1828 wird aus der Gattung Discula s. str. zu Callina gestellt und ein weiteres fossiles Taxon C. waldeni sp. n. in dieser Gattung neu beschrieben.

Resumo

No presente trabalho o grupo genérico Hystricella R. T. Lowe, 1855 é revisto com base em critérios morfológicos, anatómicos e genéticos. É descrito um novo género, Wollastonia gen. n., duas novas espécies atuais, W. jessicae sp. n. e W. klausgrohi sp. n. e uma nova subespécie também atual, W. jessicae monticola ssp. n. São também descritas neste novo género cinco novas espécies fósseis: H. microcarinata sp. n., W. beckmanni sp. n., W. falknerorum sp. n., W. ripkeni sp. n. e H. inexpectata sp. n. São designados lectótipos para as espécies, Helix vermetiformis R. T. Lowe, 1855, H. leacockiana Wollaston, 1878, H. oxytropis R. T. Lowe, 1831, H. duplicata R. T. Lowe, 1831 e H. oxytropis var. ß subcarinulata Wollaston, 1878. São designados neótipos para as taxones Helix bicarinata G. B. Sowerby I, 1824, Helix bicarinata var. ß aucta Wollaston, 1878 e Discula bulverii W. Wood, 1828. Os taxa aucta e subcarinulata são elevados à categoria de espécie. É demonstrado que o (sub) género, até agora monotípico, Callina R. T. Lowe, 1855, não está relacionado com o grupo genérico Discula, mas sim com o grupo genérico Hystricella e o seu estatuto de género é confirmado. O táxon D. bulverii W. Wood, 1828 é transferido do género Discula s. str. para o género Callina e é descrita uma nova espécie fóssil adicional, C. waldeni sp. n.

Keywords

Callina, Discula, Hystricella, Wollastonia gen. n., Macaronesia, Porto Santo (Madeira Archipelago), recent, Quaternary, phylogeny

Introduction

The island of Porto Santo (42.17 km²) is the northernmost island of the Madeiran Archipelago (Fig. 1), situated in the eastern Atlantic Ocean off the northwest African coast. As with the other islands of the archipelago, i.e., the island of Madeira and the Ilhas Desertas, Porto Santo is of volcanic origin, with its oldest subaerial deposits dated at 14.2 to 13.1 Ma before present to the Middle Miocene (Geldmacher et al. 2000; Ribeiro and Ramalho 2010). Thus, there was nearly three times as much time on Porto Santo for the evolution of an endemic land snail fauna compared to the island of Madeira with an estimated age of 5.2 to 4.6 Ma before present (Geldmacher et al. 2000; Ribeiro and Ramalho 2010) or to the Ilhas Desertas which are with approximately 3.6 Ma (Geldmacher et al. 2000), even younger than Madeira. The finding of a land snail from 20 to 13 Ma old Neogene deposits of Ilhéu de Cima, a satellite islet off southwestern Porto Santo, which Groh (1984) referred to Caseolus (Leptostictea) sp., suggests a relatively early colonization of Porto Santo by terrestrial gastropods belonging to lineages which are still present on the island today. Eleven genera and subgenera are currently considered to be endemic to Porto Santo incl. offshore islets: Leiostyla (Craticula) R. T. Lowe, 1852 (Lauriidae), Amphorella (Fusillus) R. T. Lowe, 1852 (Ferussaciidae), Serratorotula Groh & Hemmen, 1986, Lemniscia R. T. Lowe, 1855, Pseudocampylaea L. Pfeiffer, 1877, Callina R. T. Lowe, 1855, Discula (Mandahlia) Forcart, 1965 and Hystricella R. T. Lowe, 1855 (Geomitridae), Leptaxis (Katostoma) R. T. Lowe, 1855 (Hygromiidae), Lampadia Albers, 1854 and Idiomela T. D. A. Cockerell, 1921 (Helicidae). In total, 91 of the hitherto 102 known species and subspecies (c. 89%) recorded from Porto Santo are endemic (67 recent and 24 fossil taxa) resulting in a density of endemism of 2.13 taxa per square kilometre. Taking into consideration that most (sub-) species today only exist in the higher eastern part of the island, this value increases to 4.7 taxa per square kilometre, a value that is unique when measured on a global scale. This is especially noteworthy, since on Porto Santo, contrary to Madeira, the vertical differentiation of habitats was greatly reduced due to massive erosion in the past million years as evidenced by deeply cut ravines, relatively thick Aeolian deposits in the island’s central part (Ribeiro and Ramalho 2010) and a large marine abrasion platform surrounding the island, with abrasion values of 12 cm per year (Lietz and Schwarzbach 1971).

Figure 1. 

Map of Porto Santo with offshore islets and map of the Madeiran Archipelago in the Atlantic Ocean.

The documentation of the land snail diversity of Porto Santo started in 1824 when George Brettingham Sowerby I described the first four land snails from that island, among them Helix bicarinata, the type species of the genus Hystricella. The first more in-depth investigations of the terrestrial mollusc fauna of the Madeiran Archipelago were carried out by the clergyman Richard Thomas Lowe who visited the archipelago in 1828 for the first time. The results of his colleting efforts in that year were published in 1831 in his important synopsis of the fauna “Primitiæ Faunæ et Floræ Maderæ et Portus Sancti”, in which many of the land snails from Porto Santo considered as valid taxa today were named and described. From 1832 until 1854 R. T. Lowe served as Anglican chaplain in the archipelago and the material that he collected during these years formed the basis for twelve additional publications on the malacofauna of the archipelago (see Bank et al. 2002).

During this period only few additional taxa had been described, e.g., by Férussac (1832) and Deshayes (1835, 1850) in Férussac and Deshayes (1819–1851), Férussac (1835), Pfeiffer (1846), and Albers (1854). António da Costa de Paiva (Barão de Castelo de Paiva) described a number of species in 1866 and published a comprehensive thesis on the Madeiran land snail fauna in 1867, presenting an overview of the knowledge of the time.

Another important contribution towards an inventory of the malacofauna of the Madeira Archipelago was published by Thomas Vernon Wollaston under the title “Testacea Atlantica” in 1878, in which he summarised all the knowledge of the time on the non-marine molluscs of the Mid-Atlantic islands including the results of his five extended expeditions to the Madeiran Archipelago between 1847 and 1855. In this book, T. V. Wollaston listed ten taxa under the section Hystricella of the genus Helix Linnaeus, 1758, namely H. bicarinata var. aucta Wollaston, 1878, H. bicarinata, H. echinoderma Wollaston, 1878, H. echinulata R. T. Lowe, 1831, H. leacockiana Wollaston, 1878, H. turricula R. T. Lowe, 1831, H. oxytropis R. T. Lowe, 1831, H. turricula var. pererosa Wollaston, 1878, H. oxytropis var. subcarinulata Wollaston, 1878, and H. vermetiformis R. T. Lowe, 1855.

Subsequent researchers have not added any new taxa to the Hystricella-group, but evaluated its constituent taxa supra-specifically differently, without any substantial taxonomic basis, mostly placing them at a sub-generic level in the genus Discula R. T. Lowe, 1852. Furthermore, the status of many nominal taxa was, and still remains, controversial, ranging from treatments as mere varieties to subspecies or species. The two most up-to-date publications listed nine (Bank et al. 2002), viz. seven (Seddon 2008) specific and subspecific taxa in the genus Hystricella, the latter ignoring (except two) described fossil taxa from Quaternary deposits. Groh et al. (2009) published additions and corrections to Seddon (2008), including also three fossil taxa belonging to the genus Hystricella.

Anatomical investigations are currently lacking for most species currently placed in the genus Hystricella. The only exception is H. turricula, the anatomy of which was described by Watson (1923) in detail. Mandahl-Barth (1950) provided additional anatomical data for many geometrid taxa, but only repeated the results of Watson (1923) with regard to Hystricella because of the lack of preserved soft parts. Although Seddon (2008) provided distribution maps and added comments on the known distribution in the IUCN Red List (Seddon 2011ae) for five recent taxa currently classified in Hystricella, some of the records presented in those publications seem to be erroneous or highly unlikely and ought to be critically revised.

In the present contribution, we present a comprehensive revision of the species currently assigned to the genus Hystricella including, aside from conchological comparisons, anatomical descriptions of all recent taxa (except for W. vermetiformis) as well as molecular phylogenetic analyses on the basis of mitochondrial as well as nuclear DNA sequences. Distribution data for all taxa are critically revised and stratigraphic as well as biogeographic relations are discussed.

Materials and methods

Collecting and preservation of samples

Recent, living snails were collected by hand. Although specimens were quite abundant in many populations (often reaching densities of more than 50 specimens per square meter), we limited sampling to a maximum of 15–20 specimens per site for ethical and conservation reasons. The developmental stage of each specimen was carefully checked during the collecting process and all juvenile and subadult specimens were left in the field. Half of the selected specimens were immediately fixed in absolute ethanol after collection in order to preserve the DNA for molecular investigations. The remaining specimens were drowned in water for 6–10 hours and subsequently fixed in 80% buffered ethanol. This was done to ensure that most of the distal parts of the snail’s body (foot, head, and distal genitalia) were stretched out from the shell, which facilitates dissection for morphological investigations. Two weeks after the first fixation, the ethanol solution was changed to remove the precipitate that mostly consists of mucus and denatured proteins. In addition to living specimens, empty shells from recent populations were collected to obtain a better impression of the shell morphology and its intra-specific as well as intra-population variability.

Most of the subfossil to fossil material was collected by hand. Fossiliferous deposits were identified directly in the field or with the help of a geological map. At some sites with aeolinite deposits sediment was collected and immediately sieved in the field in order to separate the sandy part from the coarser portion of the sample that was expected to contain fossil shells. Larger samples of strongly cemented material were carefully crushed in the field. The smaller pieces were brought to the laboratory where they were soaked in a 2% solution of hydrogen peroxide (H2O2) and then rinsed with boiling water to separate the shells and to remove any agglutinations and encrustations adhering to them. The shells cleaned in this way were again washed with water and finally dried.

Morphological investigations

Shells were photographed with a Canon EOS camera equipped with 60 mm macro lenses mounted on a Kaiser microslide frame for multi-image stacking. The shells of all the dissected specimens and additional empty shells were photographed in front, bottom, side, and top view. Maximum shell diameter (D) and maximum shell height (H) were measured using a calliper. Additional measurement, i.e., height of the first (body) whorl (FW), peristomal angle (PA), diameter of umbilicus (DU), standardised number of tubercles on the shell surface (see Fig. 2), and the number of whorls of the protoconch, the teleoconch and their sum were taken using an image editing software. Mean values, standard deviations as well as D/H and FW/H ratios were calculated using MS Excel.

Figure 2. 

Standardisation method for counting the tubercles on the shell surface. AB Maximum diameter CD Maximum height EF height of last whorl HG height of second whorl IC height of third whorl; peristoma angle, measured as the angle between the peristomal plane and the horizontal axis of the shell JK width of the last whorl measured along the maximum diameter (JK/2)2 square on the lower surface of the last whorl delimiting the area for the count of tubercles. The centre of the square corresponds to the mid point between J and K and the length of its sides is JK/2. This method allows to compare different specimens and taxa as the area of the square depends on the shell’s overall dimensions and is always proportional (the tubercles that partially traverse the contour of the square were included in the count of tubercles).

Dissections and examination of the anatomy were performed under a Zeiss stereoscope with a ring LED illumination apparatus, connected to a digital, high-resolution camera and a camera lucida. The genitalia were isolated from the rest of the body, usually after crushing the shell, using very fine and pointed micro-tweezers (Dumostar Biology 55) in a Petri dish with the bottom filled with black paraffin. The genitalia were fixed with very fine steel micro pins (commonly used for the preparation of microlepidopteran specimens in entomology). The internal features of genitalia (including cross and longitudinal sections) were examined after dissection with micro tweezers or by a pair of biological micro scissors (Aesculap OC series). Measurements were taken using a millimetric measurement scale. All examined genitalia were photographed in different positions (40 to 50 high-resolution images depicting all relevant anatomical features) in order to create an image database. Drawings were prepared by accurately tracing the most representative digital images after contrast enhancement with a picture editing software. The drawings, instead of digital photos, were used here because photos of the genitalia do not usually allow the reader to easily observe finer anatomical/morphological details of the soft tissues (such as small, fine pleats, striae, folds, papillae, ornamentations and diverticula). The drawings were performed when the samples were still displayed under the stereoscope in order to constantly check their morphology in case of doubtful situations.

For the preparation of jaws and radulae individual buccal masses were removed and immersed in a 2 M potassium hydroxide (KOH) solution for 5 h before extracting the jaw and the radula, which were then preserved in 70% ethanol for further investigations. Jaws and radulae were mounted and observed directly, i.e., without sputter coating, under a low vacuum SEM (Miniscope TM-1000, Hitachi High-Technologies, Tokyo).

Molecular data preparation and phylogenetic analyses

For molecular genetic analyses samples of foot muscle tissue stored in 70–96% ethanol from representatives of all recent (sub-) species (except H. vermetiformis) and of species potentially belonging to the Hystricella group existing on the island of Porto Santo and of additional specimens of geomitrid species belonging to the nominal genera Discula, Caseolus R. T. Lowe, Callina and Serratorotula Groh & Hemmen, 1986 were used (see Table 1 for details). To root phylogenetic trees Cochlicella conoidea (Draparnaud, 1801) (Geomitridae, Geomitrinae, Cochlicellini) was included as outgroup (see Table 1). Total genomic DNA was extracted following a slightly modified version of the protocol of Sokolov (2000) as detailed in Scheel and Hausdorf (2012). Partial sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) and (for a subset of samples representing all genus-group taxa, see Table 1) of the nuclear rRNA gene cluster (including partial sequences of the 18S rDNA, the complete internal transcribed spacer 1 (ITS1), 5.8S rDNA and internal transcribed spacer 2 (ITS2) as well as partial sequences of the 28S rDNA) were amplified by polymerase chain reaction (PCR) using the primer pairs LCO1490 plus HCO2198 (Folmer et al. 1994) and Hyg18S_Fw (5’-GCT ACT ATC GAT TGA GCG GTT CAG-3’, J. Harl, pers. comm.) and Hyg28S_Rv: 5’-CGT CCC ACA CAC CAC AGT T-3’, J. Harl, pers. comm.), respectively, following the protocols described in Neiber and Hausdorf (2015) and Harl et al. (2017), respectively. Both strands of the amplified products were sequenced at Macrogen Europe Laboratory (Amsterdam, The Netherlands). Information on vouchers and GenBank accession numbers are compiled in Table 1.

Vouchers, locality data and GenBank accession numbers of Geomitrinae samples used for molecular analyses.

Taxon Voucher number Latitude / Longitude GenBank accession number
cox1 18S rDNA + ITS1 + 5.8S rDNA + ITS2 + 28S rDNA
Hystricella bicarinata HY03_2 33°04'16"N/16°18'53"W MG575049 MG575189
Hystricella bicarinata HY03_3 33°04'16"N/16°18'53"W MG575050
Hystricella bicarinata HY04_1 33°04'42"N/16°20'00"W MG575051 MG575190
Hystricella bicarinata HY10_1 33°04'51"N/16°18'41"W MG575052
Hystricella bicarinata HY10_2 33°04'51"N/16°18'41"W MG575053
Hystricella bicarinata HY10_3 33°04'51"N/16°18'41"W MG575054
Hystricella bicarinata HY32_1 33°04'38"N/16°19'48"W MG575055
Hystricella bicarinata HY32_2 33°04'38"N/16°19'48"W MG575056
Hystricella bicarinata HY33_1 33°04'52"N/16°19'26"W MG575057
Hystricella bicarinata HY33_2 33°04'52"N/16°19'26"W MG575058
Hystricella bicarinata HY33_3 33°04'52"N/16°19'26"W MG575059 MG575191
Hystricella bicarinata HY41_1 33°05'04"N/16°19'21"W MG575060
Hystricella bicarinata HY42_1 33°04'48"N/16°18'31"W MG575061
Hystricella bicarinata HY42_2 33°04'48"N/16°18'31"W MG575062
Hystricella bicarinata HY42_3 33°04'48"N/16°18'31"W MG575063
Hystricella bicarinata HY43_1 33°04'55"N/16°20'07"W MG575064
Hystricella bicarinata HY43_2 33°04'55"N/16°20'07"W MG575065
Hystricella bicarinata HY45_2 33°04'42"N/16°18'01"W MG575066
Hystricella bicarinata HY45_3 33°04'42"N/16°18'01"W MG575067 MG575192
Hystricella bicarinata HY47_1 33°05'01"N/16°19'14"W MG575068 MG575193
Hystricella bicarinata HY47_2 33°05'01"N/16°19'14"W MG575069
Hystricella bicarinata HY47_3 33°05'01"N/16°19'14"W MG575070
Hystricella bicarinata MN3003 33°05'02"N/16°19'14"W MG575071
Hystricella bicarinata MN3005 33°04'44"N/16°17'59"W MG575072
Hystricella bicarinata MN3008 33°04'15"N/16°18'55"W MG575073
Hystricella bicarinata MN3009 33°05'04"N/16°19'21"W MG575074
Hystricella bicarinata MN3014 33°04'52"N/16°19'26"W MG575075
Hystricella bicarinata MN3016 33°04'42"N/16°20'00"W MG575076
Hystricella bicarinata MN3018 33°04'32"N/16°19'38"W MG575077
Hystricella bicarinata MN3019 33°04'42"N/16°18'01"W MG575078
Hystricella bicarinata MN3020 33°04'55"N/16°20'07"W MG575079
Hystricella bicarinata MN3022 33°05'01"N/16°19'14"W MG575080
Hystricella bicarinata MN3023 33°04'51"N/16°18'41"W MG575081
Hystricella bicarinata MN3029 33°04'48"N/16°18'31"W MG575082
Hystricella bicarinata MN3047 33°04'44"N/16°17'59"W MG575083
Hystricella bicarinata MN3049 33°05'34"N/16°19'11"W MG575084
Hystricella echinulata HY39_1 33°05'29"N/16°18'14"W MG575085
Hystricella echinulata HY39_2 33°05'29"N/16°18'14"W MG575086
Hystricella echinulata HY39_3 33°05'29"N/16°18'14"W MG575087
Hystricella echinulata HY40_1 33°05'38"N/16°18'01"W MG575088
Hystricella echinulata HY40_2 33°05'38"N/16°18'01"W MG575089
Hystricella echinulata HY40_3 33°05'38"N/16°18'01"W MG575090
Hystricella echinulata MN3004 33°05'36"N/16°18'14"W MG575091
Hystricella echinulata MN3006 33°05'29"N/16°18'14"W MG575092
Hystricella echinulata MN3010 33°05'38"N/16°18'01"W MG575093
Hystricella bicarinataxechinulata HY06_1 33°05'42"N/16°19'23"W MG575094
Hystricella bicarinata x echinulata HY35_1 33°05'35"N/16°18'25"W MG575095
Hystricella bicarinata x echinulata HY35_2 33°05'35"N/16°18'25"W MG575096
Hystricella bicarinata x echinulata HY35_3 33°05'35"N/16°18'25"W MG575097
Hystricella bicarinata x echinulata HY36_1 33°05'57"N/16°19'32"W MG575098
Hystricella bicarinata x echinulata HY36_2 33°05'57"N/16°19'32"W MG575099
Hystricella bicarinata x echinulata HY36_3 33°05'57"N/16°19'32"W MG575100
Hystricella bicarinata x echinulata HY37_1 33°06'09"N/16°19'25"W MG575101
Hystricella bicarinata x echinulata HY37_2 33°06'09"N/16°19'25"W MG575102 MG575194
Hystricella bicarinata x echinulata MN3007 33°05'35"N/16°18'25"W MG575103
Hystricella bicarinata x echinulata MN3011 33°06'09"N/16°19'25"W MG575104
Hystricella bicarinata x echinulata MN3015 33°05'57"N/16°19'32"W MG575105
Hystricella bicarinata x echinulata MN3026 33°05'42"N/16°19'23"W MG575106
Hystricella bicarinata x echinulata MN3027 33°04'16"N/16°18'53"W MG575107
Wollastonia jessicae jessicae HY05_1 33°03'44"N/16°19'35"W MG575108 MG575195
Wollastonia jessicae jessicae HY05_2 33°03'44"N/16°19'35"W MG575109
Wollastonia jessicae jessicae HY05_3 33°03'44"N/16°19'35"W MG575110
Wollastonia jessicae jessicae HY34_1 33°03'47"N/16°19'41"W MG575111
Wollastonia jessicae jessicae HY34_2 33°03'47"N/16°19'41"W MG575112
Wollastonia jessicae jessicae HY34_3 33°03'47"N/16°19'41"W MG575113
Wollastonia jessicae jessicae MN3017 33°03'47"N/16°19'41"W MG575114
Wollastonia jessicae jessicae MN3021 33°03'44"N/16°19'35"W MG575115
Wollastonia jessicae monticola HY03_1 33°04'16"N/16°18'53"W MG575116
Wollastonia klausgrohi HY31_1 33°04'06"N/16°18'52"W MG575117 MG575196
Wollastonia klausgrohi HY31_2 33°04'06"N/16°18'52"W MG575118
Wollastonia klausgrohi HY31_3 33°04'06"N/16°18'52"W MG575119
Wollastonia klausgrohi MN3028 33°04'06"N/16°18'51"W MG575120
Wollastonia leacockiana HY01_1 33°02'57"N/16°22'04"W MG575121
Wollastonia leacockiana HY01_2 33°02'57"N/16°22'04"W MG575122 MG575197
Wollastonia leacockiana MN3002 33°02'39"N/16°22'11"W MG575123
Wollastonia leacockiana MN3024 33°02'57"N/16°22'04"W MG575124
Wollastonia oxytropis HY38_1 33°04'42"N/16°17'56"W MG575125 MG575198
Wollastonia oxytropis MN3001 33°04'43"N/16°18'19"W MG575126
Wollastonia oxytropis MN3013 33°04'42"N/16°17'56"W MG575127
Wollastonia oxytropis MN3048 33°04'41"N/16°17'57"W MG575128
Wollastonia turricula MN3000 33°03'13"N/16°16'48"W MG575129
Callina bulverii DI04_1 33°04'51"N/16°18'41"W MG575130
Callina bulverii DI15_2 33°04'16"N/16°18'53"W MG575131 MG575199
Callina bulverii DI15_3 33°04'16"N/16°18'53"W MG575132
Callina bulverii DI27_1 33°04'06"N/16°18'52"W MG575133
Callina bulverii DI28_1 33°04'38"N/16°19'48"W MG575134
Callina rotula DI23_1 33°05'35"N/16°18'25"W MG575135
Callina rotula DI25_1 33°04'42"N/16°17'51"W MG575136
Callina rotula DI26_1 33°05'57"N/16°19'32"W MG575137
Callina rotula DI31_1 33°06'09"N/16°19'25"W MG575138
Callina rotula DI31_2 33°06'09"N/16°19'25"W MG575139
Callina rotula DI35_1 33°04'48"N/16°18'31"W MG575140
Callina rotula DI35_2 33°04'48"N/16°18'31"W MG575141
Callina rotula DI37_1 33°05'29"N/16°18'14"W MG575142
Callina rotula DI37_2 33°05'29"N/16°18'14"W MG575143
Callina rotula DI44_1 33°05'38"N/16°18'01"W MG575144
Callina rotula DI44_2 33°05'38"N/16°18'01"W MG575145 MG575200
Callina rotula MN3051 33°04'48"N/16°18'31"W MG575146
Discula (Discula) attrita DI05_1 33°04'44"N/16°18'37"W MG575147 MG575201
Discula (Discula) attrita DI05_2 33°04'44"N/16°18'37"W MG575148
Discula (Discula) attrita DI05_3 33°04'44"N/16°18'37"W MG575149
Discula (Discula) attrita DI12_1 33°02'57"N/16°22'04"W MG575150
Discula (Discula) attrita DI12_2 33°02'57"N/16°22'04"W MG575151
Discula (Discula) attrita DI21_2 33°03'37"N/16°17'55"W MG575152
Discula (Discula) attrita DI29_1 33°03'45"N/16°17'57"W MG575153
Discula (Discula) attrita DI29_2 33°03'45"N/16°17'57"W MG575154
Discula (Discula) attrita DI29_3 33°03'45"N/16°17'57"W MG575155
Discula (Discula) attrita DI29_4 33°03'45"N/16°17'57"W MG575156
Discula (Discula) attrita DI29_5 33°03'45"N/16°17'57"W MG575157
Discula (Discula) attrita DI34_1 33°04'48"N/16°18'31"W MG575158
Discula (Discula) attrita DI38_1 33°02'38"N/16°22'56"W MG575159
Discula (Discula) attrita DI38_2 33°02'38"N/16°22'56"W MG575160
Discula (Discula) attrita DI43_2 33°04'01"N/16°18'26"W MG575161
Discula (Discula) attrita MN3053 - - MG575162
Discula (Discula) calcigena DI42_1 33°04'16"N/16°17'58"W MG575163 MG575202
Discula (Discula) discina DI08_1 33°05'48"N/16°18'54"W MG575164
Discula (Discula) discina DI08_2 33°05'48"N/16°18'54"W MG575165
Discula (Discula) discina DI08_3 33°05'48"N/16°18'54"W MG575166
Discula (Discula) discina DI08_4 33°05'48"N/16°18'54"W MG575167
Discula (Discula) discina DI16_1 33°05'25"N/16°20'58"W MG575168
Discula (Discula) discina DI16_2 33°05'25"N/16°20'58"W MG575169
Discula (Discula) discina DI16_3 33°05'25"N/16°20'58"W MG575170
Discula (Discula) discina DI16_4 33°05'25"N/16°20'58"W MG575171
Discula (Discula) discina DI22_1 33°04'44"N/16°18'37"W MG575172
Discula (Discula) discina DI22_2 33°04'44"N/16°18'37"W MG575173
Discula (Discula) discina DI22_3 33°04'44"N/16°18'37"W MG575174
Discula (Discula) discina DI22_4 33°04'44"N/16°18'37"W MG575175
Discula (Discula) discina DI24_1 33°05'48"N/16°18'54"W MG575176
Discula (Discula) discina DI24_2 33°05'48"N/16°18'54"W MG575177 MG575203
Discula (Discula) polymorpha alleniana MN3052 32°52'03"N/17°09'56"W MG575178
Discula (Discula) polymorpha arenicola DI06_1 32°44'41"N/16°41'58"W MG575179 MG575204
Discula (Discula) polymorpha arenicola DI06_2 32°44'41"N/16°41'58"W MG575180 MG575205
Discula (Discula) pulvinata DI30_1 33°05'07"N/16°21'21"W MG575181 MG575206
Discula (Discula) pulvinata DI30_2 33°05'07"N/16°21'21"W MG575182
Discula (Discula) pulvinata DI30_3 33°05'07"N/16°21'21"W MG575183
Discula (Discula) tabellata DI03_1 32°38'21"N/16°51'03"W MG575184
Discula (Discula) tabellata DI03_2 32°38'21"N/16°51'03"W MG575185
Disculatestudinalis MN3077 33°06'14"N/16°19'18"W MG575186 MG575207
Caseolus (Caseolus) innominatus innominatus CA08_1 32°52'03"N/17°09'56"W MG575187 MG575208
Caseolus (Leptostictea) hartungi CA10_1 33°05'15"N/16°21'16"W MG575188 MG575209
Serratorotula juliformis MN3036 33°03'45"N/16°17'57"W MG575210
Cochlicella (Cochlicella) conoidea SP165 41°08'15"N/08°40'00"W KY818425 1 KY818623 1

ChromasPro 1.7.1 (Technelysium) software was used to assemble forward and reverse sequence reads. Nuclear rDNA sequences were aligned with MAFFT 7 (Katoh and Standley 2013) using the Q-INS-i iterative refinement algorithm, whereas cox1 sequences were aligned with MUSCLE (Edgar 2004) as implemented in MEGA 6.0 (Tamura et al. 2013). We used maximum likelihood (ML), Bayesian Inference (BI) and maximum parsimony (MP) approaches to reconstruct the phylogenetic relationships. Appropriate evolutionary models for the mitochondrial and nuclear sequence data sets were selected with PartitionFinder 1.1.1 (Lanfear et al. 2012) conducting an exhaustive search with separate estimation of branch lengths for each partition and with the Bayesian information criterion (as recommended by Luo et al. 2010) as criterion to select among models. As the nuclear ribosomal DNA sequence were hardly variable among ingroup and outgroup taxa, nuclear sequence data were not divided further into partitions. The models to choose from were restricted to those available in MrBayes 3.2.6 (Ronquist et al. 2012) as well as in Garli 2.1 (Zwickl, 2006). As best-fit partitioning scheme, the PartitionFinder analysis suggested to use the HKY + I + G model for the mitochondrial sequences and the GTR + I + G model for the nuclear sequences.

BI analysis was performed using MrBayes. Metropolis-coupled Monte Carlo Markov chain (MC3) searches in MrBayes were run with four chains in two separate runs for 50,000,000 generations with default priors, trees sampled every 1,000 generations under default heating using the best-fit model as suggested by PartitionFinder. Diagnostic tools in MrBayes, including Effective Sample Size (ESS) values > 200, Potential Scale Reduction Factors ~ 1.000 and an average standard deviation of split frequencies < 0.01, were used to ensure that the MC3 searches had reached stationarity and convergence. The first 5,000,000 generations of each run were discarded as burn-in.

ML analyses were performed with Garli and iqtree 1.5.3 (Nguyen et al. 2015) using the best-fit models as suggested by PartitionFinder and otherwise default settings. Support values were computed by bootstrapping (BS) with 1,000 replications.

MP searches were carried out with PAUP* 4.0b10 (Swofford 2002) using 1,000 random-addition-sequence replicates and TBR branch swapping. Support values were computed by bootstrapping with 1,000 replications.

BS values above 70% are interpreted as meaningful node support and PP values above 0.95 as statistically significant support.

Collection acronyms

ANSP Academy of Natural Sciences of Drexel University, Philadelphia, PA, USA

CFW private collection of Frank Walther, Essen, Germany

CJG private collection of Jochen Gerber, Chicago, USA

CKG private collection of Klaus Groh, Bad Dürkheim, Germany

CMN private collection of Marco T. Neiber, Sehnde, Germany

CWDM private collection of Willy De Mattia, Trieste, Italy

DRAM Direcção Regional do Ambiente da Madeira, Funchal, Madeira, Portugal

GNM Göteborgs Naturhistorika Museum, Göteborg, Sweden

HNHM Hungarian National History Museum, Budapest, Hungary

NHC Natural History Collections, University of Edinburgh, Edinburgh, Great Britain

NHM Natural History Museum, London, Great Britain

NHMW Natural History Museum Wien, Austria, Malacological collection

NMS National Museum of Scotland, Edinburgh, Great Britain

MMF Museu de Historia Natural do Funchal (formerly Museo Municipal do Funchal), Funchal, Madeira, Portugal

MMUE Manchester Museum, University of Manchester, Great Britain

NMW National Museum of Wales, Cardiff, Great Britain

OUMNH Oxford University Museum of Natural History, Oxford, Great Britain

RAM Royal Albert Memorial Museum, Exeter, Great Britain

SMF Forschungsinstitut und Naturmuseum Senckenberg, Frankfurt/M., Germany

ZMH Zoological Museum Hamburg, Hamburg, Germany

Morphological abbreviations

Genital anatomy

A atrium

AF atrial folds

AG albumen gland

BC bursa copulatrix

DBC duct of bursa copulatrix

DP distal penis

F flagellum

FAP accessory papilla of the flagellum

FO free oviduct

FMP main papilla of the flagellum

LDL left dorsal lobe

LSPP longitudinal section of penial papilla

MR retractor muscle

OSD ovispermiduct

PC penial channel

PCE penial channel exit

PM penial matrix

PN pneumostoma

PP penial papilla

PW penial wall

SL subpneumostomal lobe

RLL right lateral lobe

SP spongy pilaster of the distal penis

SVA single vaginal appendage (dartless stylphore)

TSPP transversal section of penial papilla

V vagina

VD vas deferens

VG vaginal glands

VS vaginal section

Shell

D maximum shell diameter

H maximum shell height

FW height of the first (body) whorl

NT number of tubercles

NW number of whorls

PA peristomal angle

DU diameter of umbilicus

Taxa exclusively known from fossil material are indicated by a dagger symbol (†).

Results and discussion

Phylogenetic analyses

The phylogenetic analyses, both based on the mitochondrial cox1 data alone and the concatenated mitochondrial and nuclear data recovered the included Geomitrini as a mostly well-supported monophyletic group (Fig. 3). Within this clade, several groups, here interpreted as genus-group taxa, were mostly significantly/meaningfully supported (Fig. 3), albeit relationships among these groups did not receive significant/meaningful support in all analyses. Neither the genus Hystricella nor the genus Discula in the sense of Bank et al. (2002), Seddon (2008), Groh et al. (2009) or Bank (2009) were recovered as monophyletic groups. Species formerly included in Hystricella were assigned to two different clades (Fig. 3).

Figure 3. 

Bayesian 50% majority rule consensus tree based (A) on the concatenated sequences of cox1 and 18S rDNA + ITS1 + 5.8S rDNA + ITS2 + 28S rDNA and (B) on the cox1 sequences alone. Posterior probability values (first value), bootstrap support values from the maximum likelihood analysis with Garli (second value) and iqtree (third value) and maximum parsimony analysis with PAUP* (fourth value) are indicated at the nodes. Only posterior probability values ≥ 0.5 and bootstrap support values ≥ 50% are shown. For phylogenetic relationships of Hystricella, Wollastonia gen. n., Callina, and Discula species included in the analyses, see Figure 46.

The clade including the type species of Hystricella, H. bicarinata, also included H. echinulata and received significant/meaningful support in all phylogenetic analyses except in the ML analysis with Garli based on cox1 data alone (Fig. 4). Within the Hystricella clade two well-separated clades which largely correspond to specimens morphologically assigned to either H. bicarinata or H. echinulata were recovered (Fig. 4). Hystricella bicarinata has its distribution centre in the eastern central to southeastern part of Porto Santo, whereas H. echinulata is restricted to the northeastern part of the island (Fig. 4). In a small area in the north of Porto Santo populations with intermediate or deviating morphologies (i.e., presence/absence of a double keel on the body whorl and presence/absence of papilla on the inner wall of the terminal part of the flagellum) were found. In the cox1 phylogenies these specimens, either clustered with H. bicarinata or H. echinulata (Fig. 4) and are here interpreted as putative hybrids between the two species.

Figure 4. 

Bayesian 50% majority rule consensus tree based on cox1 sequences of Hystricella species. Posterior probability values (first value), bootstrap support values from the maximum likelihood analysis with iqtree (second value) and Garli (third value) and maximum parsimony analysis with PAUP* (fourth value) are indicated at the nodes. Only posterior probability values ≥ 0.5 and bootstrap support values ≥ 50% are shown. The inset map shows the distribution of H. bicarinata (blue), H. echinulata (green) and putative hybrids of both species (red) on Porto Santo. The tip labels on the tree are coloured accordingly. For information on vouchers, see Table 1 and the corresponding material lists under the species’ sections. The inset tree shows the position of Hystricella in relation to the other investigated genus-group taxa based on the analysis of concatenated mitochondrial and nuclear sequences as shown in Figure 3.

The other clade including species hitherto assigned to Hystricella, although only supported in the BI and MP analyses (Figs 3, 5), will be formally described as Wollastonia gen. n. below. This clade includes W. leacockiana comb. n., W. turricula comb. n., and W. oxytropis comb. n., as well as three additional recent taxa that will be formally described below: W. klausgrohi sp. n., W. jessicae sp. n., and W. jessicae monticola ssp. n. (Fig. 5). The relationships of most of the taxa within Wollastonia gen. n. could not be well resolved (Fig. 5) on the basis of the phylogenetic analyses of the cox1 data. Specifically, although the monophyly of W. oxytropis comb. n. was well-supported in all analyses, the phylogenetic analyses failed to recover the monophyly of W. klausgrohi sp. n. (Fig. 5). However, the very distinct shell morphology and genital anatomy of W. oxytropis comb. n. (see below) clearly supports the recognition of two distinct, though closely related species.

Figure 5. 

Bayesian 50% majority rule consensus tree based on cox1 sequences of Wollastonia gen. n. species. Posterior probability values (first value), bootstrap support values from the maximum likelihood analysis with Garli (second value) and iqtree (third value) and maximum parsimony analysis with PAUP* (fourth value) are indicated at the nodes. Only posterior probability values ≥ 0.5 and bootstrap support values ≥ 50% are shown. For information on vouchers, see Table 1 and the corresponding material lists under the species’ sections. The inset tree shows the position of Wollastonia gen. n. in relation to the other investigated genus-group taxa based on the analysis of concatenated mitochondrial and nuclear sequences as shown in Figure 3.

Interspersed between the Hystricella and Wollastonia gen. n. clades, a clade containing Callina rotula (R. T. Lowe, 1831), the type species of Callina R. T. Lowe, 1855, was placed as the sister group of Hystricella with significant/meaningful support in the BI and MP analyses (Figs 3, 6A). Callina was up till now either regarded as a monospecific genus related to the genus Discula (Waldén 1983; Schileyko 2005), or included as a subgenus in Discula, but the phylogenetic analyses presented here do not support the monophyly of Callina plus Discula s. str. (i.e., the clade including the type species of the genus D. discina (R. T. Lowe, 1852), see Figs 3, 6A). Interestingly, the phylogenetic analyses recovered a close relationship of C. rotula and C. bulverii (Wood, 1828), comb. n., a taxon up till now included in Discula s. str. (Bank et al. 2002; Seddon 2008; Bank 2009).

In the phylogenetic analyses, both based on the concatenated and the cox1 data set, a specimen of Discula testudinalis (R. T. Lowe, 1852) from Porto Santo was placed in a sister group relationship to the clade including Hystricella, Wollastonia gen. n. and Callina, albeit not supported in all analyses (Fig. 3). The remaining Discula species were grouped together with statistical support in the BI and MP analyses based on the concatenated mitochondrial and nuclear data and in all analyses based on the cox1 data alone (Fig. 6B). Within the Discula clade three well-supported clades were placed in a polytomy (Fig. 6B): the first of these clades grouped two specimens of D. tabellata (R. T. Lowe, 1852) from Madeira together, the second group included specimens of D. discina (R. T. Lowe, 1852) from Porto Santo and the third clade included specimens of D. attrita (R. T. Lowe, 1831), D. pulvinata (R. T. Lowe, 1831) and D. calcigena (R. T. Lowe, 1831) from Porto Santo as well as D. polymorpha (R. T. Lowe, 1831) from Madeira. Within the latter clade, D. attrita was recovered as a mostly well-supported sister group of the remaining three taxa, and D. polymorpha as the sister group of a clade containing D. calcigena and D. pulvinata (Fig. 6B). Discula pulvinata was recovered as a paraphyletic group with respect to D. pulvinata, however, divergences within this clade were rather low overall and the branching patterns not well-resolved.

Figure 6. 

Bayesian 50% majority rule consensus tree based on cox1 sequences of (A) Callina and (B) Discula species. Posterior probability values (first value), bootstrap support values from the maximum likelihood analysis with Garli (second value) and iqtree (third value) and maximum parsimony analysis with PAUP* (fourth value) are indicated at the nodes. Only posterior probability values ≥ 0.5 and bootstrap support values ≥ 50% are shown. For information on vouchers, see Table 1 and the corresponding material lists under the species’ sections. The inset tree shows the position of Callina and Discula in relation to the other investigated genus-group taxa based on the analysis of concatenated mitochondrial and nuclear sequences as shown in Figure 3.

Systematic account

The suprageneric classification follows Razkin et al. (2015) and Neiber et al. (2017), elevating the Geomitridae from subfamily to family rank with Geomitridae plus Canariellidae Schileyko, 1991 as the sister group of Hygromiidae Tryon, 1866.

Helicoidea Rafinesque, 1815

Geomitridae C. R. Boettger, 1909

Geomitrinae C. R. Boettger, 1909

Syn. Ochthephilinae Zilch, 1960 in Wenz and Zilch (1959–1960)

Geomitrini C. R. Boettger, 1909

Hystricella R. T. Lowe, 1855

Discula auct., partim [non R. T. Lowe, 1852].

Helix (Ochthephila) sensu Albers (1850) and Albers (1854), partim.

Helix (Octephila), Paiva (1867) [incorrect subsequent spelling Ochthephila Albers, 1850], partim.

Geomitra (Actinella (Hystricella)), Pilsbry (1893–1895).

Geomitra sensu Bank et al. (2002).

Type species, by original designation in R. T. Lowe (1855)

Helix bicarinata G. B. Sowerby I, 1824 = Hystricella bicarinata (G. B. Sowerby I, 1824).

Lowe (1855: 186–187) describes the new genus Hystricella in the section § 24, basing his description upon shell features only, as follows:

(Typ. H. bicarinata, Sow.). T. perf. v. angustae umbil. conuloidea v. trochiformis, aliquando turrito-pyramidata acute v. distincte 1–2-carinata solidiuscula aspero-granulata v. echinulata subfasciata. Anfr. 6–9 lente crescentes planiusculi, ult. valde carinato subtus planato, antice deflexo. Umbil. parvus anguste cylindricus v. subspiralis constrictus. Apert. circularis circinata labris connexis; perist. continuum solutum expanso-reflexiusculum tenue acutum.

Lowe (1855: 186–187) cites for the genus (under section § 24) the following species:

H. bicarinata G. B. Sowerby I, 1824

H. echinulata R. T. Lowe, 1831

H. oxytropis R. T. Lowe, 1831

H. turricula R. T. Lowe, 1831

H. vermetiformis R. T. Lowe, 1855

Hystricella mustelina Reeve, 1854 [under authorship R. T. Lowe, 1855], currently considered as a subspecies of Discula (Discula) cheiranthicola Reeve, 1854 [even though the description was prepared by R. T. Lowe in 1854 the work was only published in 1855 and therefore the earlier publication of that name in Reeve in 1854 has priority].

Hystricella cheiranticola R. T. Lowe, 1831 and its morphae (later put in the mono-specific subgenus [as section] Turritella by Wollaston 1878 [non Lamarck 1799]).

Later, H. mustelina (currently Discula (Discula) cheiranthicola mustelina (Reeve, 1854)) and H. cheiranticola (currently Discula (Discula) cheiranthicola cheiranthicola (R. T. Lowe, 1831)) were assigned to the genus Discula R. T. Lowe, 1852 (Mandahl-Barth 1950).

Description of the genus

Shell. The shell is dextral, hairless and it is usually conical and scalariform. The protoconch is whitish to dark brown, with 1.3 to 2.2 whorls. It is almost smooth along the first whorl and shows fine radial striae and extremely small, scattered tubercles along its remaining portion. The teleoconch has from 4.2 to 5.0 rapidly increasing whorls. It is usually dark brown with brick red and/or dark violet colour shades. The dark areas of the shell are mottled with more or less light brown to whitish areas, usually placed longitudinally and slightly slanting. No band pattern is visible along the upper whorls. On the lower part of the last whorl two well-defined, dark bands are visible that can differ in width. The area around the umbilicus is usually the lightest in colour. The spire is slightly variable in height, ranging in shape from compressed to somewhat more elevated. Along the last and the penultimate whorls one to two evident keels are present. The external upper surface has very fine but clearly visible, irregularly spaced growth lines. Along the last whorls the growth lines usually disappear along the lateral area and reappear on the lower part. Irregularly disposed tubercles are found all over the teleoconch. The dimensions of the tubercles tend to increase slightly from the first toward the last whorl, the density remaining, however, approximately the same. The tubercles are somewhat denser along the keels of the penultimate and last whorls, letting the keel/keels appear like a rough chord. On the lower part of the last whorl the tubercles are usually bigger and slightly less dense than in the remaining parts of the shell. The last whorl is large, with a contribution of 60% of the total shell height and descending towards the aperture. The umbilicus is open but very narrow, concentric and has a diameter of approximately 10% of the maximum shell diameter. The aperture is elliptical with a faint thickening along the inner side of the last whorl. The peristome is continuous, slightly reflected with the columellar margin somewhat thicker and more reflected.

Body. Head and neck are grey to pale grey, slightly transparent. The sides and posterior upper section of the foot are whitish. The sole of the foot is whitish and longitudinally divided into three areas. The central area is smooth whereas the two lateral areas are equipped with bands of muscles roughly arranged in a chevron pattern. The mantle border is grey to dark grey with five more or less developed lobes. The ratio among lateral and dorsal lobes varies from specimen to specimen also in the same population. In some specimens, particular lobes (regardless if lateral or dorsal) may be completely missing. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible.

Genitalia. The general arrangement of the genitalia is semi-diaulic monotrematic. A convoluted to almost straight first hermaphroditic duct arises from a multi-lobated gonad. The albumen gland is long and moderately thin and connected to an equally long sperm-oviduct consisting of a prostatic and a uterine portion. Distally, the prostatic part extends into a thin vas deferens, twice as long as the sperm-oviduct, terminating in the penial complex. The distal portion of the uterine part inserts into the free oviduct, then transforming into a vagina at the level of the insertion of the duct of the bursa copulatrix. The free oviduct is usually three to four times shorter than the vagina. The duct of the bursa copulatrix is usually wide, approximately as long as the penis and uniform in diameter. This duct terminates in a variable, oval to roundish, small bursa copulatrix. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually two or three, equally long and very rarely branched glands. A short and thin vaginal appendix arises from the vagina’s wall, immediately distal of the glandular tuft. Very smooth, little elevated and spaced pleats run longitudinally along the inner surface of the vagina, reaching into the genital atrium as far as the genital orifice. The atrium can be short or moderately long. The penial complex consists of a flagellum, an epiphallus (which extends from insertion of the vas deferens to the penial retractor muscle) and a penis that inserts into the genital atrium. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually twice as long as the epiphallus. Its internal walls can be either completely smooth or ornamented with very small papillae distributed mainly close to the blunt end. The epiphallus is usually extremely short and its internal walls are smooth. The retractor muscle is well developed, strong and is variable in length. The penis lacks a muscular or glandular sheath. It is thick-walled and approximately four times longer than the flagellum. It is usually cylindrical to sometimes slightly swollen in its distal part. The inner walls of the penis are usually smooth or with very smooth, little elevated and spaced pleats which run longitudinally and reach the genital atrium. The section where the penial papilla is located is usually detectable from the outside by virtue of a fine circular swelling corresponding to the origin of the papilla itself. The penial papilla is very variable in size, ranging from 1/6 to 1/2 of the total penial length and is conical to subcylindrical in shape. The inner lumen of the penial papilla is filled with a spongy and sturdy tissue which directly connects with the walls of the epiphallus. It has smooth external walls with the opening emerging apically. The channel of the penial papilla is thin and narrow. The longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward.

Jaw and radula. The jaw and radular apparatus of Hystricella is depicted in Fig. 8. No notable variability was found among the species of the genus. The jaw is odontognathous, almost straight to markedly arched, with 13 to 15 smooth ridges. The radula ribbon is typical helicoid, it is elongated but not very slender. Central tooth present, tricuspid, the main cusp (endocone) is rhomboid, pointed; the ectocones are much smaller than the endocone; they are triangular, pointed. There are 19–20 laterals and marginals which do not distinctly differ from each other, i.e., their shape changes gradually from the first laterals towards the marginals. Laterals are bicuspid, endocones are rhomboid or triangular and pointed. The ectocones are much smaller, pointed, and triangular. The endocones of the central tooth and the first laterals are approximately of the same size. Both, the endocone and the ectocone of the laterals gradually become bifurcated towards the marginal teeth, but the ectocones may occasionally have three cusps as well. The cusps of the marginals are gradually decreasing in size; therefore, the outermost marginals appear nearly serrated.

Distribution

The genus Hystricella is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal). The genus is restricted to the eastern, mountainous part of the island and occurs there only in the central-northern section of this area (Fig. 7). Species assigned to the genus are commonly found on the slopes of Pico do Castelo, Pico do Facho, Pico de Juliana, Pico da Gandaia, Rocha de Nossa Senhora, the western slopes of Pico do Concelho, and those of the Pico Branco and Terra Chã complex. It is also commonly found at lower elevations of Serra de Dentro, Barranco Branco, and Lombo de Paredes. Recent Hystricella are absent from the southeastern part of the island, i.e., from Vale do Touro, Portela, Pico do Maçarico, and Pico do Baixo. It is likewise not present on the small islets surrounding the main island, namely Ilhéu de Cima, Ilhéu de Baixo, and Ilhéu de Ferro. Subfossil representatives of the genus are found mainly in the mud and aeolinite deposits along the southeastern coast, namely Vale do Touro, Ponta do Passo, Barbinha, and Calhau da Serra de Fora.

Figure 7. 

Distribution of the genus Hystricella. Filled circles refer to recent and open circles to fossil records.

Figure 8. 

Radulae and jaws of Hystricella species. A Hystricella bicarinata, Ribeira da Areia B Hystricella echinulata, path to Pico Branco.

Ecology

Representatives of the genus Hystricella are commonly found under volcanic rocks scattered on grassland in open fields that are more or less strongly sloping. They have been found under stones in pine woods (Pico do Castelo) or in cracks and crevices of rocky walls (Pico da Gandaia). Disturbed or anthropogenic habitats have also been colonised by representatives of the genus, such as stone walls (Pedregal de Dentro) or terraced areas (southern slopes of Pico do Castelo). Specimens aestivate on the lower surfaces of stones or rocks, frequently forming large clusters of individuals attached to one another, reaching more than 40 to 50 in number. Under a single stone of roughly 60 × 40 cm approximately 200 individuals were counted (southern slopes of Pico do Facho).

Nomenclatural and taxonomic remarks

Hystricella was considered a subgenus of Helix for a long time (until Wollaston 1878) or was replaced by Ochthephila Beck, 1837 (Albers 1850) or Octephila Paiva, 1867 (Paiva 1867). Later it was considered as a subgenus of Discula R. T. Lowe, 1852 and only since 2002 (Bank et al. 2002) accepted as a distinct genus.

Bank et al. (2002) used the generic name Geomitra Swainson, 1840 despite Herrmannsen’s (1847: 470) selection of the nominal species Helix tiarella Webb & Berthelot, 1833 as the type species of that genus. The decision of Herrmannsen was followed by all subsequent authors (e.g., Wollaston 1878; Mandahl-Barth 1950; Waldén 1983). The reason to contradict that type selection was the fact that it was wrong with respect to the rules of the International Commission on Zoological Nomenclature’s (ICZN) Code of Zoological Nomenclature (hereafter ‘the Code’) Art. 67.2.1: Swainson introduced Geomitra describing and depicting tiarella, namely on p. 166 and 332, but he did not mention that name, but instead only bicarinata, which therefore would be the type species by monotypy. In consequence Hystricella R. T. Lowe, 1855 would become a synonym of Geomitra and Geomitra sensu auct. has to be referred to Craspedaria R. T. Lowe, 1852. Nevertheless, this decision was much criticised (Seddon 2008) and a new study of the Code revealed a solution which permits the stabilisation of the former use of Geomitra (Groh et al. 2009). Following Art. 70.3 of the Code the combination of the figure of tiarella with the name bicarinata can be interpreted as a misidentification by Swainson and therefore following Art. 70.3.2, the name tiarella becomes available for type selection under the synonymous name Geomitra bicarinata Swainson, 1840. This was already recognised by Pfeiffer (1847: 191) who listed Swainson’s combination as a synonym of Helix tiarella (cf. Groh et al. 2009).

Comparison and comments

Hystricella shows a number of morphological characters that clearly distinguishes it from the other native geomitrid genera from Porto Santo, in particular with regard to the genus Discula s. lat., into which the Hystricella species were previously placed (Mandahl-Barth 1950; Waldén 1983). On the basis of the shell, the main distinguishing feature of Hystricella from Discula s. lat. is the continuous and detached peristome. On the contrary, in Discula s. lat. and Callina (Figs 10–12) the peristome is always interrupted, forming only a thickening or a callous along the parietal region but not a real and proper detached lip. Other minor differences can be found in the ornamentation of the shell’s surface. Hystricella always possesses round, somewhat spaced tubercles, whereas Discula s. lat. and Callina shows mainly elongated, sometimes drop-like tubercles arranged in a regular pattern. In Hystricella the size of the tubercles can reach large dimensions in comparison to the overall size of the shell and their size can remarkably vary on the same shell. Actinella s. lat. and Caseolus s. lat. (see Figs 13–16) also possess an interrupted peristome. Most Caseolus species have a more or less granulated shell’s surface and, at first glance, could therefore be confused with Hystricella. However, a closer look reveals the different peristome and the overall different shape, with the whorls always rounded and usually without any prominent keel. Serratorotula (Fig. 17) has an extremely ornamented shell that is easily distinguishable from Hystricella. The shell form of Heterostoma is very different from that of Hystricella and these two genera are therefore easily distinguishable (see Seddon 2008: 125). Some species of the genus Spirorbula sometimes have shells with a continuous peristome with detached lips along the parietal side. The very depressed shell shape and different surface ornamentation of Spirorbula however, readily distinguishes the two genera (Fig. 18). Lemniscia usually possesses a smooth and rather glossy shell without tubercles or papillae (Fig. 19). The shell morphology of Wollastonia gen. n. and its differences with regard to Hystricella will be discussed in the section on Wollastonia gen. n. below.

Figures 9–19. 

Shells of Portosanctan and Madeiran Geomitridae. 9 Hystricella bicarinata, Pico do Castelo, S slope around the Miradouro 10 Discula discina, Porto da Morena 11 Discula (Mandahlia) tectiformis, Pico do Baixo 12 Callina rotula, Cabeco dos Bades 13 Actinella (Plebecula) littorinella, E of Pico do Castelo 14 Caseolus (C.) innominatus portosanctanus, Ribeira da Areia 15 Caseolus (Helicomela) punctulatus punctulatus, Fonte da Areia 16 Caseolus (Leptostictea) leptosticus, Ponta do Garajau, Madeira 17 Serratorotula juliformis, Pico de Ana Ferreira 18 Spirorbula depauperata, Pico de Ana Ferreira 19 Lemniscia michaudi, Terra Chã. Scale bar: 1 cm.

With regard to genital morphology, Hystricella shows a unique feature that allows the separation of the genus from all native Portosanctan Geomitridae, except from Wollastonia gen. n. The main difference is the shape of the penial flagellum which is always short and has a remarkably blunt apex (Fig. 20). Discula s. lat. and Callina, Serratorotula, and Lemniscia (Figs 21–25) have a pointed, more or less elongated flagellum. Hystricella is easily distinguishable from Caseolus s. lat. and Actinella s. lat. by virtue of the single vaginal appendages instead of the two that are present in these genera (see Figs 26–29). Spirorbula is also easily distinguishable from Hystricella because members of this genus possess two extremely long, and sometimes branched, vaginal appendages and a genital atrium with structures on the inner wall consisting of large and partially fringed folds (see Fig. 30).

Figures 20–30. 

Outer distal genitalia of Portosanctan and Madeiran Geomitridae. 20 Hystricella bicarinata, Capela da Graça 21 Discula polymorpha alleniana, Porto Moniz, Madeira 22 Discula (Mandahlia) tectiformis, Pico do Baixo 23 Callina rotula, Cabeco dos Bades 24 Serratorotula juliformis, Pico de Ana Ferreira 25 Lemniscia michaudi, Terra Chã 26 Actinella (Plebecula) littorinella E of Pico do Castelo 27 Caseolus (C.) innominatus portosanctanus, Ribeira da Areia 28 Caseolus (Helicomela) punctulatus punctulatus, Fonte da Areia 29 Caseolus (Leptostictea) leptosticus, Ponta do Garajau, Madeira 30 Spirorbula depauperata, Pico de Ana Ferreira. Scale bars 1 mm.

Hystricella bicarinata (G. B. Sowerby I, 1824)

Figs 31–32, 33–37, 38–45, 46–53, 54

List of synonyms

1824 Helix bicarinata G. B. Sowerby I: 58, pl. 3 fig. 7.

1828 Helix bicarinata – Wood: pl. 8 fig. 85.

1831 Helix duplicata R. T. Lowe: 58, pl. 6 fig. 30 [unjustified replacement name for Helix bicarinata Sowerby I, 1824 [non Helix C.[ochlitoma] bicarinata J. Férussac, 1821, a secondary homonym of Bulimus bicarinatus Bruguière, 1792 = Archachatina bicarinata (Bruguière, 1792). See Taxonomic Remarks below].

1846 Helix bicarinata – L. Pfeiffer: 141, pl. 91 figs 8–11.

1847 Helix bicarinata – L. Pfeiffer in L. Pfeiffer 1847–1848: 190.

1854 Helix bicarinata – Reeve in Reeve 1851–1854: pl. 142 figs 908–909.

1854 Helix (Ochthephila) bicarinata – Albers: pl. 9 figs 1–4.

1855 Helix (Hystricella) bicarinata – R. T. Lowe: 186.

1867 Helix (Octephila) bicarinata – Paiva: 45.

1878 Helix (Hystricella) bicarinata – Wollaston: 161–163.

1888 Helix bicarinata – Tryon in Tryon and [Pilsbry] 1888: 33, pl. 7 fig. 90.

1894 Geomitra bicarinata – Pilsbry in Pilsbry 1893–1895: 242.

1931 Geomitra (Actinella) bicarnata – Nobre: fig. 37.

1950 Discula (Hystricella) bicarinata bicarinataMandahl-Barth 1950: 31, 55.

1966 Discula (Hystricella) bicarinata – S. G. A. Jaeckel: 53.

1983 Discula (Hystricella) bicarinata bicarinata – Waldén: 267.

2002 Geomitra bicarinata bicarinata – Bank et al.: 124.

2008 Hystricella bicarinata – Seddon: 79, pl. 29 fig. E, map 178.

2011 Hystricella bicarinata – Seddon: e.T6724A12800659.

Type material

Despite intensive research in multiple museum collections (NHM, NMW, MMUE, ANSP, NHC, NMS, OUMNH, RAM, SMF) that could have held the type material of the taxon, no such material could be traced and therefore we deem it reasonable to assume that the type material is lost. To stabilise the present interpretation of Helix bicarinata G. B. Sowerby I, 1824 and to clarify its taxonomic status we designate a neotype here, which is deposited in the collection of the SMF under the No. SMF 348936 (see Fig. 33). The original figures of Helix bicarinata G. B. Sowerby I, 1824 from Sowerby (1824: pl. 3 fig. 7) 32 and Helix duplicata R. T. Lowe, 1831 from R. T. Lowe (1831: pl. 6 fig. 20) are depicted in Figs 31–32. The neotype (Fig. 33) is consistent with the figure in Sowerby (1824: pl. 3 fig. 7) and the original description (see below), especially with regard to size, shape and the presence of two keels on the body whorl. The taxon was originally described from Porto Santo without more detailed locality data, which is consistent with origin of the specimen selected as neotype.

Figures 31–32. 

31 Original figure of Helix bicarinata G. B. Sowerby I, 1824 from Sowerby (1824: pl. 3 fig. 7) 32 Original figure of Helix duplicata R. T. Lowe, 1831 from R. T. Lowe (1831: pl. 6 fig. 20).

Locus typicus

Pico do Castelo, S slope around the Miradouro, under stones in pine wood, 33°04'42"N/16°20'00"W, 270 m (through the designation of the neotype).

Further material examined

All from Porto Santo, ANSP H 20185/13, NW slope of Pico Branco, 33°05'50"N/16°18'57"W to 33°05'52"N/16°18'49"W, 150–200 m, leg. J. & C. Hemmen, Jan. 8 1981; ANSP H 11776/2, NW slope of Pico de Juliana, 33°05'34"N/16°19'25"W, up to 450 m, leg. J. & C. Hemmen, Jan. 6 1981; CKG/12, Pico de Juliana, under stones, 33°05'31"N/16°19'20"W, 365 m, leg. K. Groh, Jun. 23 1983; ANSP H 11788/11, CMN/3, SW slope of Pico do Juliana, 33°05'30"N/16°19'23"W, 360 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 13 1985; CFW 11149/1, Pico Juliana, old quarry on the southern slope, 33°05'28"N/16°19'17"W, 330 m, leg. F. Walther & E. M. Gryl, Apr. 3 2017; ANSP H 11769/3, Ribeiro das Esmoitadas (E Camacha), 33°05'27"N/16°20'17"W, 130 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 13 1985; CKG/2, SW of Pico de Juliana, 33°05'14"N/16°19'32"W, 360 m, leg. K. & C. Groh, Oct. 27 1980; CFW 11158/10, Pico do Facho, NW slope, 33°05'12"N, 16°19'38"W, 370 m, leg. F. Walther, Apr. 3 2017; ANSP H 20186/1, NE slope of Pico do Facho, 33°05'07"N/16°19'23"W, 430–450 m, leg. K. Groh & J. Hemmen, Jun. 28 1983; CWDM/6, CMN/ 3, ridge between Pico do Facho and Pico da Gandaia, stone walls, 33°05'04"N/16°19'21"W, 460 m, leg. W. De Mattia & J. Macor, May 25 2015; CWDM/15, N slope of Pico do Facho in Tamarix wood, under stones, 33°05'04"N/16°19'25"W, 475 m, leg. W. De Mattia & J. Macor, May 25 2015; CKG/44, CMN/6, W of Pico do Facho, under stones, 33°05'04"N/16°19'33"W, 450 m, leg. K. Groh, Jun. 29 1983; ANSP H 11778/c. 40, SW slope of Pico do Facho, 33°05'03"N/16°19'31"W, 460–480 m, leg. K. Groh & J. Hemmen, Jun. 28 1983; CKG/24, CMN/44, upper Ribeira Formosa between Covau and Serra de Fora, under stones, 33°05'02"N/16°19'14"W, 140 m, leg. K. Groh, Jun. 19 1983; ANSP H 11775/13, W slope of Pico do Facho, 33°05'02"N/16°19'38"W, leg. J. & C. Hemmen, Jan. 6 1981; ANSP H 11834/19 [sub H. echinulata], summit of Pico da Gandaia, 33°05'01"N/16°19'14"W, 440 m, leg. J. & C. Hemmen, Jan. 6 1981; CWDM/11, CMN/7, Pico da Gandaia, southern rocky cliffs close to the top, under stones, 33°05'01"N/16°19'14"W, 440 m, leg. W. De Mattia & J. Macor, May 25 2015; ANSP H 11779/24, SW slope of Pico do Facho, 33°04'56"N/16°19'39"W to 33°05'02"N/16°19'30"W, 300–450 m, leg. K. Groh & J. Hemmen, Jul. 1 1983; CWDM/15, CMN/3, N and E slopes and summit of Pico do Castelo, under stones in pine wood, 33°04'55"N/16°20'07"W, 350 m, leg. W. De Mattia & J. Macor, May 22 2015; CWDM/25, CMN/5, S slope of Pico do Facho, along path at the S border of the pine wood, under stones, 33°04'52"N/16°19'26"W, 355 m, leg. W. De Mattia & J. Macor, May 17 2015; CKG/8, Pico do Castelo, S slope around the Miradouro, under stones in pine wood, 33°04'51"N/16°20'03"W, 420 m, leg. K. & C. Groh, Oct. 27 1980; CWDM/22, CMN/4, Ribeira da Areia, serpentine 240 m NNW the quarry, under stones, 33°04'51"N/16°18'41"W, 140 m, leg. W. De Mattia & J. Macor, May 21 2014; ANSP H 11787/c. 30, approx. 1 km NE Capela da Graça, 33°04'49"N/16°19'04"W, 250 m, leg. J. & C. Hemmen, Jan. 4 1981; CWDM/12, CMN/4, lake shore S of Ribeira da Serra de Dentro, under stones and in stone walls, 33°04'48"N/16°18'31"W, 70 m, leg. W. De Mattia & J. Macor, May 22 2015; ANSP H 20187/1, NW slope of Pico do Concelho, 33°04'44"N/16°18'04"W to 33°04'43"N/16°18'01"W, 250–300 m, leg. K. Groh & J. Hemmen, Jul. 29 1983; CKG/8, CMN/8, Pico do Concelho, NW of the top, under stones, 33°04'43"N/16°17'59"W, 260 m, leg. K. Groh, Jun. 29 1983; ANSP H 11835/12 [sub H. echinulata], NW slope of Pico do Concelho, 33°04'43"N/16°18'01"W, approx. 280 m, leg. J. & C. Hemmen, Jan. 6 1981; ANSP H 12780/32, NW slope of Pico do Concelho, 33°04'43"N/16°18'01"W, 250–300 m, leg. K. Groh & J. Hemmen, Jun. 6 1983; CWDM/15, CMN/2, summit of Pico do Concelho, under stones, 33°04'42"N/16°18'01"W, 280 m, leg. W. De Mattia & J. Macor, May 18 2015; CWDM/18,CMN/4, Pico do Castelo, S slope around the Miradouro, under stones in pine wood, 33°04'42"N/16°20'00"W, 270 m, leg. W. De Mattia & J. Macor, Feb. 12 2012; CMN/1, Pico do Castelo, S slope around the Miradouro, under stones in pine wood, N slope, 33°04'42"N/16°20'01"W to 33°04'51"N/16°20'03"W, 300–430 m, leg. K. Groh Jul. 1 1983; ANSP H 11783/24, Pico do Castelo, 33°04'42"N/16°20'01"W to 33°04'51"N/16°20'03"W, 350–430 m, leg. K. Groh & J. Hemmen, Jul. 1 1983; CWDM/8, CMN/4, path from Capela da Graça to Pico do Castelo along the Levada, under stones, 33°04'38"N/16°19'48"W, 165 m, leg. W. De Mattia & J. Macor, May 17 2015; CKG/3, CMN/68, Capela da Graça up to Pico de Facho-Motos de Fora, under stones, 33°04'38"N/16°19'33"W, 200 m, leg. K. Groh, Jun. 23 1983; ANSP H 11785/9 spms, Ribeiro do Formoso, 33°04'36"N/16°19'04"W, 130 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 13 1985; ANSP H 11777/12, approx. 1 km S Serra de Dentro, 33°04'33"N/16°18'25"W, 160 m, leg. J. & C. Hemmen, Jan. 8 1981; ANSP H 11782/c. 30, slope between the SE slope of Pico do Castelo and Capela da Graça, 33°04'32"N/16°19'38"W, 160 m, leg. J. & C. Hemmen, Jan. 4 1981; CFW 11161/7, Casinhas, N of Capela da Graça, 33°04'27"N/16°19'27"W, 150 m, leg. F. Walther, Apr. 4 2017; CKG/11, CMN/1, Pico do Baixo, 33°04'26"N/16°19'44"W to 33°04'46"N/16°19'44"W, 100–250 m, leg. K. Groh, Jul. 11, 1983; CWDM/23, Engula, under stones, 33°04'19"N/16°19'01"W, 150 m, leg. W. De Mattia & J. Macor, May 18 2015; CFW 11159/>10, E slope of Rocha de Nossa Senhora, 33°04'19"N/16°19'01"W, 150 m, leg. F. Walther, Apr. 3 2017 ANSP H 11771/18, N of Portela (E of Vila Baleira), 33°04'07"N/16°19'17"W, 120 m, leg. J. & C. Hemmen, Jan. 4 1981; CKG/2, CMN/1, Capela da Graça up to Pico do Facho-Motos de Fora, N slope, 33°04'38"N/16°19'33"W to 33°05'04"N/16°19'33"W, approx. 200–450 m, leg. J. Gerber, K. Groh & J. Hemmen, Jun. 28 1985; ZMH 120610/2, foot of Pico do Castelo, c. 33°04'37"N/16°19'49"W, 170 m, ex coll. W. Fauer, leg. J. & C. Hemmen, Jul. 11 1983; ZMH 110165/68, slopes of Pico do Facho, under stones; c. 33°04'59"N/16°19'25"W, 430 m a.s.l., leg. E. Clauss, Sep. 22 1992; ZMH 24288/2, Madeira Archipelago, without exact locality data, ex coll. Altonaer Museum; ZMH, 24289/1, Porto Santo, without exact locality data, ex coll. Museum Klagenfurt; ZMH 24290/3, Porto Santo, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn.

Original description

From Sowerby (1824): testa subglobosa, spira breviuscula, subconica; anfractibus quinque quadratis, mediane carinis duabus, superiore obtusiuscula: apertura integra, rotunda, peristomate distincto: umbilico parvo. Axis 316, diam. ¼ unc.

Diagnostic features of the shell

Shell as in the genus description. The main diagnostic feature is the presence of two well-developed keels along the penultimate and body whorl. The lower keel is usually slightly stronger and more evident than the upper one along both whorls. The overall shape of the shell of Hystricella bicarinata is always conical and scalariform by virtue of a “shoulder” that lets the contour of the whorls appear markedly angular. The sutures are deep and well-marked (see Figs 33–37).

Figures 33–37. 

Shells of Hystricella bicarinata. 33 neotype of Hystricella bicarinata, Pico do Castelo, S slope around the Miradouro, SMF 348936 34 syntype of H. duplicata R. T. Lowe 1831, NHM 1948.7.8.34; Shells of Hystricella bicarinata 35 Capela da Graça 36 Pico do Castelo, S slope around the Miradouro 37 Pico da Gandaia. Scale bar 1 mm.

Measurements

D 4.9 ± 0.2 mm (range 4.4–5.3 mm); H 3.8 ± 0.2 mm (range 3.4–4.2 mm); FW 2.4 ± 0.2 mm; PA 53.5 ± 2.4°; DU 0.4 ± 0.09 mm; NT 21 ± 6; NW 5.6 ± 0.1 (range 5.1–5.75) (n = 40). Ratio D/H 1.3; ratio FW/H 0.6.

Body

Body as in the genus description.

Genital anatomy

As in the genus description. The albumen gland is long and connected to an equally long sperm-oviduct. The prostatic part extends into a thin vas deferens that is twice as long as the sperm-oviduct. The free oviduct is somewhat variable in length, but is usually three to four times shorter than the vagina. The duct of the bursa copulatrix is usually wide, slightly shorter than the penis, opening out into a roundish, small bursa copulatrix. One tuft of digitiform glands consisting of two, more rarely three never branching glands. The inner ornamentation of the vagina consists of very wide, low, and smooth pleats running longitudinally as far as the genital atrium. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus. Its internal walls are completely smooth. The epiphallus is short and its internal walls are smooth. The penis lacks any muscular or glandular sheath. It is thick-walled and approximately four times longer than the flagellum. It is cylindrical and sometimes slightly swollen in its distal part. The inner walls of the penis are usually smooth or with very smooth, little elevated and spaced pleats which run longitudinally and reach the genital atrium (see Figs 3853).

Figures 38–45. 

Genitalia and anatomy of Hystricella bicarinata. Pico do Castelo, S slope around the Miradouro: 38 whole genitalia excluding part of OSD, AG and gonads 39 ornamentation of the inner walls of the distal penis, the vagina and the genital atrium 40 transverse section of penial papilla. Pico da Gandaia: 41 whole genitalia excluding gonads 42 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium. Ribeira de Serra de Dentro: 43 jaw. Pico da Gandaia: 44 mantle border. Ribeira de Serra de Dentro: 45 whole genitalia excluding part of OSD, AG and gonads. Scale bars 1 mm.

Figures 46–53. 

Genitalia and anatomy of Hystricella bicarinata. Capela de Graça: 46 whole genitalia excluding part of OSD, AG and gonads 47 penial papilla 48 longitudinal section of the penial papilla 49 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium. Ridge between Pico do Facho and Pico da Gandaia: 50 whole genitalia excluding part of OSD, AG and gonads. NE slopes of Pico do Castelo: 51 section of vagina. Capela da Graça: 52 jaw. S slopes Pico do Facho: 53 mantle border. Scale bars 1 mm.

Distribution

Hystricella bicarinata is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal) (Fig. 54). The species is restricted to the eastern, mountainous part of the island and is present only in the central section of this area. It is commonly found on the slopes of Pico do Castelo, Pico do Facho, Pico de Juliana, Pico da Gandaia, Rocha de Nossa Senhora, and the western slopes of Pico do Concelho. It is also commonly found at lower elevations of the Serra de Dentro, Barranco Branco, and Lombo de Paredes. It is not present on the small islets surrounding the main island, namely Ilhéu de Cima, Ilhéu de Baixo, and Ilhéu de Ferro. Subfossil representatives of Hystricella bicarinata are not known. Seddon (2008: 181) depicts the distribution of H. bicarinata. The four southernmost points indicate the presence of the species also for the southern ridge of eastern Porto Santo. We here infer that these localities are based upon misidentifications with other species, probably some representatives of Wollastonia, i.e., W. jessicae sp. n. or W. klausgrohi sp. n.

Figure 54. 

Distribution of Hystricella bicarinata.

Ecology

Hystricella bicarinata is commonly found under volcanic rocks scattered on grassland in open fields that are more or less sloping. It has also been found under stones in pine woods (Pico do Castelo) or in cracks and crevices on rocky walls (Pico da Gandaia) or terraced areas (southern slopes of Pico do Castelo). The specimens aestivate on the lower surfaces of stones or rocks, frequently forming large clusters of 40 to 50 individuals attached one to another. Under a single stone of roughly 60 × 40 cm approximately 200 individuals were observed (southern slopes of Pico do Facho).

Comparison and comments

The presence of two keels along the body whorl easily distinguishes H. bicarinata from H. echinulata. Where both taxa come into contact in the northern to northeastern part of Porto Santo (Fig. 4) intermediate populations exist however, suggesting a possible hybrid zone (see below).

At first glance, and due to the small dimensions, H. bicarinata can be confused with the fossil species H. aucta and H. microcarinata sp. n. (see Fig. 74). However, a closer analysis reveals major differences in many features of the shell. Hystricella aucta has a more solid shell with two, almost equally developed keels along the body whorl. The penultimate and the third whorl have a single strong upper keel only. The tubercles in H. aucta are much smaller and finer than in H. bicarinata (see Figs 71–73).

Hystricella microcarinata sp. n. resembles H. bicarinata with regard to dimensions and overall shape; however, the weak keels along the penultimate and body whorl and the well-developed and rather elevated growth lines allow the separation of the two species. Moreover, the tubercles in H. microcarinata sp. n. are somewhat smaller and more scattered.

Hystricella bicarinata can also resemble some of the species included in the newly described genus Wollastonia gen. n. Species such as W. turricula, W. leackociana and W. oxytropis differ in the very fine granulation present on the shell’s surface. These species do not possess evident tubercles but only small granules that are remarkably smaller in dimension than the tubercles of H. bicarinata. Moreover, the overall shape of all three above-mentioned species is different from that of H. bicarinata (see e.g. Figs 100, 119, 130). Other (sub-) species assigned to Wollastonia gen. n. such as W. vermetiformis, W. jessicae jessicae sp. n., W. jessicae monticola ssp. n., and W. klausgrohi sp. n. (see Figs 118–120, 147–149, 159–161, 168–170) are somewhat similar to and could be confused with H. bicarinata. These taxa can be readily distinguished, however, by their more scalariform shape, somewhat stronger keels, and the sparser arrangement of the tubercles. Moreover, the distributional ranges of Hystricella and Wollastonia gen. n. do not significantly overlap and molecular data strongly supports differentiation at the genus-level (thus also at species level).

Nomenclatural and taxonomic remarks

We report below a statement sent to us by Ruud Bank referring to the erroneously introduced name Helix duplicata R. T. Lowe, 1831. “The name Helix [Cochlitoma] bicarinata A. Férussac, 1821 does not exist! Férussac simply reclassified Bulimus bicarinatus Bruguière, 1792 under Helix (Cochlitoma). Thus, Helix bicarinata G. B. Sowerby I, 1824 was at that time (and only for a very short period of time) a secondary homonym of Helix bicarinata (Bruguière, 1792). Helix duplicata R. T. Lowe, 1831 was introduced to replace the name of Sowerby due to homonymy with the Férussac name, but as stated above, Férussac did not introduce such a name, it was simply a generic change for Bulimus bicarinatus Bruguière. In my opinion, the name duplicata cannot be considered a nomen novum. It would have been only a nomen novum when R. T. Lowe mentioned Bruguière as the author of the senior taxon – what he didn’t.

Mandahl-Barth (1950), Jaeckel (1966) and Waldén (1983) placed this taxon in Discula and considered Hystricella as a subgenus. Bank et al. (2002) considered the species to belong to a distinct genus (under the name Geomitra). Only recently Seddon (2008) appointed this species to the genus Hystricella and emphasised anatomical differences with the genus Discula.

Status and conservation

The opinion of Seddon (2011a) “[Hystricella bicarinata] has a total extent of occurrence of 10 km2 but is present over the eastern part of the island and in these sites it is abundant” has been confirmed by our field researches. For this reason, we think that the assessment as Near Threatened (NT) is appropriate at present.

Putative hybrid populations of H. bicarinata and H. echinulata

Material examined. All from Porto Santo, CWDM/8, Porto de Pedregal, under stones. 33°06'14"N/16°19'18"W, 20 m, leg. W. De Mattia & J. Macor, May 2014 and May 2015; CWDM/22, CKG/3, CMN/8, SMF 348933/4, NMW Z.2016.013.00005/1 and NMW Z.2016.013.00006/19, Cebecos dos Bades at confluence of two temporary creeks, under stones, 33°06'09"N/16°19'25"W, 34 m, leg. W. De Mattia & J. Macor, May 19 2015; CFW/11147/>10, Ribeira do Pedregal, lower part of the valley near confluence with the tributaries, 33°06'08"N/16°19'32"W, 50 m, leg. F. Walther & E.M. Gryl, Apr. 2 2017; CFW 11150/>10, Ribeiro do Pedregal, upper part, downstream of the abandoned houses, 33°05'57"N/16°19'32"W, 120 m, leg. F. Walther, Apr. 2 2017; CWDM/15, Pico Branco, Faja Pequena at the beginning of the path to Terra Chã, under stones, 33°05'50"N/16°18'44"W, 180 m, leg. W. De Mattia & J. Macor, May 2014; CWDM/10, CKG/1, CMN/5, Pedregal de Dentro near abandoned houses, under stones, 33°05'46"N/16°19'27"W, 195 m, leg. W. De Mattia & J. Macor, May 2015; CWDM/16, Pico de Cabrita, northern slope close to the road, under stones, 33°05'42"N/16°19'23"W, 240 m, leg. W. De Mattia & J. Macor, May 2014; CWDM/11, CMN/5, path to Pico Branco, terraced S slope of Pico Branco, under stones. 33°05'35"N/16°18'25"W, 270 m, leg. W. De Mattia & J. Macor, May 2015.

Comments. The genetic analyses revealed an area in the northeastern part of Porto Santo where both, haplotypes assigned to H. bicarinata and H. echinulata are present (Fig. 5). Some of the specimens are morphologically closer to H. echinulata with regard to the shell, but possess a H. bicarinata mitochondrial haplotype or vice versa. Some specimens may also be conchologically intermediate. Investigation of the genital system showed that much of the genital anatomy is, in fact, identical with that of either H. bicarinata or H. echinulata. However, numerous small papillae that cover the inner walls of the tip of the penial flagellum were observed in several specimens that are lacking in H. bicarinata or H. echinulata (Figs 55–70). Sometimes these papillae can slightly extend distally, towards the vas deferens opening, but never exceed to more than one third of the total flagellum length. Populations that exhibit these features usually occur at lower altitudes compared to H. echinulata or H. bicarinata, from almost sea level (Porto de Pedregal) to 240 m a.s.l. across the southern slope of Pico Branco and are limited to the northeastern part of the island, where they are distributed along the southern slopes of the Pico Branco massif, Lombo Celado, Cabecos dos Bades with Porto de Pedregal, Pedregal de Dentro, and the northern slopes of Pico de Cabrita. Because of the presence of mitochondrial haplotypes from both H. bicarinata and H. echinulata, these populations are here tentatively interpreted as hybrid populations. Further investigations that allow an estimation of gene flow among these populations will, however, be necessary to decide on their definite status. In case that these populations really are of hybrid origin, the specimens with papillae in the penial flagellum may represent an example of transgressive segregation.

Figures 55–70. 

Shells, anatomy and genitalia of the putative hybrid populations of H. bicarinata and H. echinulata. Shells: 55 Pedregal de Dentro 56 Ribeira Formosa 57 Pico de Cabrita 58–59 Cabecos dos Bades 60 Pedregal de Fora. Genitalia and anatomy. Cabecos dos Bades: 61 whole genitalia excluding part of OSD, AG and gonads 62 section of penial papilla 63 penial papilla 64 inner walls of atrium and penis 65 mantle border. Pedregal de Dentro: 66 whole genitalia excluding part of OSD, AG and gonads 67 inner walls of atrium and penis 68 jaw 69 section of penial papilla 70 vaginal glands and vaginal appendage. Scale bars 1 mm.

Hystricella aucta (Wollaston, 1878), stat. n.

Figs 71–73, 75

List of synonyms

1867 Helix (Octephila) vermetiformis var. α minor Paiva: 48 [non Helix minor mult. auct.].

1878 Helix (Hystricella) bicarinata var. ß aucta Wollaston: 162–163.

1950 Discula (Hystricella) bicarinata aucta – Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) bicarinata aucta – Waldén: 267.

2002 Geomitra bicarinata aucta – Bank et al.: 124.

2006 Discula bicarinata aucta – Cameron et al.: 31.

2008 Hystricella bicarinata aucta – Seddon: 79.

2009 Hystricella bicarinata aucta – Groh et al.: 21 fig. 25.

Type material

Despite intensive research in multiple museum collections (NHM, NMW, MMUE, ANSP, NHC, NMS, RAM, SMF) that could have held the type material of the taxon, no such material could be traced and therefore we deem it reasonable to assume that the type material is lost. To stabilise the present interpretation of Helix (Hystricella) bicarinata var. ß aucta Wollaston, 1878 and to clarify its taxonomic status we designate a neotype here, which is deposited in the collection of the SMF, under the No. SMF 348937 (see Fig. 71). The neotype is consistent with the original description (see below), especially with regard to size, shape and the presence and development of the two keels on the body whorl. The taxon was originally described from Porto Santo, which is consistent with the origin of the specimen selected as neotype.

Figures 71–74. 

Shells of Hystricella aucta. 71 neotype, SMF 348937 from Barbinha 72 Barbinha 73 Ponta da Canaveira 74 Hystricella microcarinata sp. n., holotype, SMF 348924. Scale bar: 1 mm.

Loci typici

[aucta] Barbinha, Quaternary slope deposits, "grey layer", 33°04'04"N/16°17'49"W, 8 m, (through the designation of the neotype); [var. minor]: … rara ad Zimbral d'Aréa.

Further material examined

All from Porto Santo, CKG/1, S slope of Pico do Concelho, Quaternary slope deposit, 33°04'35"N/16°18'03"W, 200–230 m, leg. K. & C. Groh, Jun. 29 1980; CKG/2, Barbinha, Quaternary slope deposits, "grey layer", 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 4 1983; ANSP H 11789/9 [sub H. bicarinata], Barbinha, Quaternary slope deposits, "red layer", 33°04'04"N/16°17'49"W, 8 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 12 1985. CKG/1, first bay S of Barbinha, Quaternary slope deposit, 33°03'51"N/16°17'46"W, 18 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 5 1983. CGK/3, Ponta da Canaveira, Quaternary aeolinites, 33°02'30"N/16°23'35"W, 50 m, Jun. 24 1983, leg. K. Groh & J. Hemmen; CGK/3, S of Ponta da Canaveira, Quaternary aeolinites, 33°02'30"N 16°23'34"W, 55 m, Oct. 26 1980, leg. K. Groh & J. Hemmen; CKG/2, Vale do Touro, Quaternary slope deposit cut by water erosion in the banks of the valley, 33°03'48"N/16°19'17"W, 15 m, leg. K. & C. Groh, Aug. 16 1980; CWDM/14, S slope of Vale do Touro hill, 50 m W of the oil tanks, fossils beds in mixed gravel and mud deposits, 33°03'47"N/16°19'26"W, 15 m, leg. W. De Mattia & J. Macor, May 2015; CFW 12172/1 fragm. [cf. aucta], Ponta da Galé, E end of tunnel, lower level [of slope deposits], coarse, red coloured gravel with large stones, 33°03'44"N/16°17'45"W, 30 m, leg. F. Walther, Apr. 4 2017; CFW 12173/16, CKG/3, S of Ponta da Canaveira, (sub-)fossil [slope-]deposits, coarse, red coloured gravel, 33°02'25"N/16°23'41"W, 30 m, leg. F. Walther, Apr. 2 2017; CFW 12175/8, E of Vila Baleira, end of Vale do Touro, (sub-)fossil [slope-] deposits, coarse, black gravel, 33°03'48"N/16°19'15"W, 20 m, leg. F. Walther, Apr. 5 2017; CFW 12174/13, CKG/2, E of Vila Baleira, S slope of the hill above Vale do Touro, W of the oil tanks, [(sub-)fossil slope-deposits of] red gravel, 33°03'47"N/16°19'26"W, 25 m, leg. F. Walther, Apr. 5 2017.

Original descriptions

[aucta]: From Wollaston 1878: There is however an appreciably larger form of this species [bicarinata] (cited in the present catalogue as the 'var. ß. Aucta’) to which the subfossil examples might perhaps be better referred, – in which the upper (or medial) keel is a trifle more horizontal and prominent, and the shell is full 3 lines (instead of only approximately 2½) across its broadest part – which was found in Porto Santo by Mr. Watson, and which I have received from him as the 'recent state of the H. vermetiformis, Lowe.' the 'var. ß. Aucta' of the H. bicarinata in its very much larger size, and in its volutions (the ultimate one of which is not quite so deflected at the aperture) being 7 in number, instead of only 6 or 6½; [var. minor]: From Paiva 1867: Variet. adest α minor, testa minore.

Redescription of the shell

Shell small for the genus, with 5.7 regularly increasing whorls, the protoconch with 1.9 whorls. The form of the shell is conical, the concave teleoconch whorls, with two prominent keels situated at the upper ⅐, respectively ⅖ of the total height of the last whorl. The last whorl measures 62%, the penultimate whorl 19% of the total shell height. The lower 60% of the body whorl beneath the second keel are rather straight, only a little convex in the middle. The suture is simple, only slightly sunken beneath the second keel of the preceding whorl. The aperture, which is inclined to the vertical axis of the shell in an angle of 49° and is descending in the last 5% of the last whorl in an angle of 38° to the horizontal axis, has an elliptical-ovate form, its width is 42% of the total shell width and its height 27% of the total shell height. It has an only slightly reflected lip, which is completely detached from the body whorl. The eccentric umbilicus, which is approximately 12% as wide as the shell, is in the upper whorls needle stitch-like. The protoconch is smooth. The teleoconch is equipped with few oblique radial ribs, seven in the penultimate quadrant of the body whorl and is additionally covered by numerous coarse tubercles. The number of tubercles in the standard quadrate of the base is 31; the tubercles are of approximately equal size. There are no traces of colouration (Figs 71–73).

Measurements

D 5.5 ± 0.5 mm (range 5.1–6.4 mm); H 4.6 ± 0.4 mm (range 4.1–5.3 mm); FW 2.8 ± 0.2 mm; PA 51 ± 2.1; DU 0.5 ± 0.03 mm; NT 18 ± 6; NW 5.5 ± 0.4 (n = 22). Ratio D/H 1.2; ratio FW/H 0.6.

Distribution

Hystricella aucta is known only from the southeastern coast of Porto Santo: from the hill immediately east of Vila Baleira (mud and slope deposits at Vale do Touro) to the mud deposits and aeolinites along the southeastern coast (Barbinha, Zimbral da Areia, and Porto dos Frades) (Fig. 75).

Figure 75. 

Distribution of Hystricella aucta.

Comparison and comments

Because of its small size, the species can only be confused with the similar sized recent H. bicarinata which, however, is somewhat larger on average, has less developed keels, especially the upper one is less prominent and has coarser and denser tubercles on its shell surface, a narrower umbilicus and a more distinctly descending aperture. The smaller H. microcarinata sp. n., which has a much more rounded globular form, bears less prominent keels on the whorls, has finer and more densely arranged tubercles, has a much narrower umbilicus and a different shape as well as differently positioned angles of the aperture. The similar sized Wollastonia beckmanni sp. n., which has a much flatter shape, has no keels on the whorls, a much wider umbilicus, much more and finer tubercles and differently positioned angles of the aperture.

Nomenclatural and taxonomic remarks

Considered by Wollaston (1878) as the fossil variation of H. bicarinata. We here consider it as a distinct species because of the shell differences. Like H. bicarinata, H. aucta has previously (Mandahl-Barth 1950, Waldén 1983, Bank et al. 2002) been listed as belonging to Discula and later on to Geomitra.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Hystricella microcarinata De Mattia & Groh, sp. n.

Figs 74, 76

Type material

SMF 348924, holotype, from loc. typ. (locus typicus), leg. W. De Mattia & J. Macor, May 2016.

Locus typicus

Porto Santo, E of Vila Baleira, S slope of the hill above Vale do Touro, 50 m W of the oil tanks, excavated Quaternary mixed gravel, 33°03'47"N/16°19'26"W, 24 m.

Diagnosis

Hystricella species with two keels on the body whorl, the upper less developed than the lower one; growth lines rather coarse, giving the impression of an irregular ribbing; tubercles on the base of the shell rather scattered and not as prominent as in H. bicarinata.

Description of the shell of the holotype

Shell very small for the genus, with 5⅓ regularly increasing whorls, the protoconch with 1.6 whorls. The form of the shell is rounded conical, the convex teleoconch whorls exhibit two flat keels that become more and more expressed; the upper keel is much less developed than the lower one; keels on the body whorl located in its upper half. The last whorl measures 69%, the penultimate whorl 15% of the total shell height. The lower half of the body whorl is, beneath the distinctly angled periphery, in frontal view nearly straight, only very slightly convex. The suture between the whorls is simple, not sunken. The aperture, which is inclined to the vertical axis of the shell in an angle of 50° and is descending in the last 5% of the last whorl in an angle of 36° to the horizontal axis, has an oblique-ovate form, its width is 43% of the shell width, its height 34% of the shell height. It has a slightly reflected lip, which is completely detached from the body whorl. The eccentric umbilicus, which is approximately 11% as wide as the shell, is shaped in the upper whorls like a pinhole. The protoconch is smooth. The teleoconch exhibits a number of oblique radial ribs, 16 in the penultimate quadrant of the body whorl and is additionally covered by numerous rough tubercles. The number of tubercles in the standard-quadrate of the base is 43. There are no traces of colouration (Fig. 74).

Measurements

D 4.1; H 4.2 mm; FW 2.7 mm; PA 49°; DU 0.3 mm; NT 12; NW 4.8 (n = 1). Ratio D/H 0.9; ratio FW/H 0.6.

Distribution

The species is only known from the type locality where it appears to be extremely rare (Fig. 76). Its close resemblance to other (sub-) fossil Hystricella taxa may have led to misidentifications during previous collecting and sorting, thus the distribution area of the species may possibly become larger after further investigations.

Figure 76. 

Distribution of Hystricella microcarinata sp. n.

Etymology

The name is a combination of the Greek name for small (μικρός = mikrós) and the Latin name for keeled (carinatus) and alludes to the small size of the shell with a keel at its periphery.

Comparison and comments

Being a (sub-) fossil species, only the shell features can be taken into account for comparisons. The globose shape is similar to that of some forms of H. echinulata; nevertheless the overall dimensions and surface sculpture of the shell clearly distinguish H. microcarinata sp. n. Because of its small size, the new species can also be confused with small specimens of H. aucta Wollaston, 1878 which, however, possesses two well-developed keels, has a wider umbilicus, a different shape and differently positioned angles of the aperture, or with Wollastonia beckmanni gen. et sp. n., which has a much flatter spire, has no keels on the whorls, a much wider umbilicus and also a different shape and differently positioned angles of the aperture.

Taxonomic remarks

The generic affiliation of this species is based exclusively on the shape of the shell and the presence of keels on the body whorl. A similar arrangement of the tubercles and keels can be found also in some Wollastonia gen. n. species that will be described below.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Hystricella echinulata (R. T. Lowe, 1831)

Figs 77–78, 79–82, 83–93, 94

List of synonyms

1831 Helix echinulata R. T. Lowe: 57, pl. 6 fig. 19.

1846 Helix echinulata – L. Pfeiffer: 140, pl. 91 figs 1–4.

1847 Helix echinulata – L. Pfeiffer in L. Pfeiffer 1847–1848: 190.

1854 Helix echinulata – Reeve in Reeve 1851–1854: pl. 142 figs 9–10.

1854 Helix echinulata – Albers: 36, pl. 9 figs 1–4.

1855 Helix (Hystricella) echinulata – R. T. Lowe: 186.

1867 Helix (Octephila) bicarinata var.α echinulata – Paiva: 45.

1878 Helix (Hystricella) echinulata – Wollaston: 160–161.

1950 Discula (Hystricella) echinulata – Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) echinulata – Waldén: 267.

2002 Geomitra echinulata – Bank et al.: 124.

2008 Hystricella echinulata – Seddon: 79, pl. 29 fig. D (and cf. E [under H. bicarinata]), map 178.

2011 Hystricella echinulata – Seddon: e.T6727A12801253.

Type material

NHM 1968.586, lectotype (herewith designated) of Helix echinulata R. T. Lowe, 1831 ex coll. R. T. Lowe. For the original figure of Helix echinulata R. T. Lowe, 1831 from R. T. Lowe (1831: pl. 6 fig. 19) and the lectotype of H. echinulata R. T. Lowe, 1831, W = 4.9 mm, Phot. B. Faria, DRAM, see Figs 77 and 78.

Figures 77–78. 

77 original figure of Helix echinulata R. T. Lowe, 1831 from R. T. Lowe (1831: pl. 6 fig. 19) and 78 lectotype of Helix echinulata R. T. Lowe, 1831, NMH 1968.586 ex coll. R. T. Lowe. Scale bar: 1 mm.

Further material examined

All from Porto Santo, ANSP H 11829/1, Ribeiro do Pedregal, 33°06'10"N/16°19'25"W, 35 m, leg. K. Groh & J. Hemmen, Jul. 11 1983; ANSP H 11828/16, CKG/5, Pico do Ninho do Guincho, 33°06'07"N/16°18'51"W, 100 m, leg. K. Groh & J. Hemmen, Jul. 11 1983; CKG/1, Ribeiro do Golfeiras E Camacha, 33°05'47"N/16°19'33"W, 170 m, leg. K. & C. Groh, Oct. 25 1980; ANSP H 11831/3, CKG/1, CMN/1, SW slope of Lombo Branco, under stones, 33°05'46"N/16°18'46"W to 33°05'38"N/16°18'13"W, 150–400 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; ANSP H 11830/4, Terra Chã, top, 33°05'46"N/16°18'14"W, 360 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 14 1985; CFW 11162/5, Pico Branco, Terra Chã (350 m E of Pico Branco), 33°05'39"N/16°17'58"W, 340 m, leg. F. Walther, Mar. 31 2017; CWDM/19, CMN/5, Terra Chã, near the "Casa Forestal", under stones in pine wood. 33°05"39"N/16°20'00"W, 340 m, leg. W. De Mattia & J. Macor, May 2014; CWDM/6, Terra Chã-Pico Branco ridge, under stones, 33°05'38"N/16°18'01"W, 335 m, leg. W. De Mattia & J. Macor, May 2015; ANSP H 11833/3, summit of Pico Branco, 33°05'38"N/16°18'14"W, 450 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; ANSP H 11836/15 [sub H. leacockiana], Pico Branco, 33°05'38"N/16°18'14"W, above 350 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 14 1985; CKG/16, Terra Chã, top, 33°05'36"N/16°18'14"W, 360 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 14 1985; CKG/2, Terra Chã, 33°05'31"N/16°18'16"W to 33°05'38"N/16°18'13"W, 320–400 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; CWDM/14, path to Pico Branco, eastern steep part of path to Pico Branco, under stones, 33°05'29"N/16°18'14"W, 320 m, leg. W. De Mattia & J. Macor, May 2014; CFW 11148/<10, SW slope of Pico Branco ca. 250 m SW of the top, 33°05'29"N/16°18'13"W, 310 m, leg. F. Walther & E. M. Gryl, Mar. 31 2017; ANSP H 11826/7, approx. 1 km N Serra de Dentro, 33°05'24"N/16°18'27"W, 165 m, leg. J. & C. Hemmen, Jan. 6 1981; ZMH 24292/1, Madeira Archipelago, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn; ZMH 24291/1, Porto Santo, without exact locality data, ex coll. Museum Klagenfurt.

Locus typicus

Hab. in monte “Pico Branco” dicto Insulae Portus Sti.

Original description

From Lowe 1831: H. testa parvula, conoidea, sub-pyramidata, depressiuscula, supra planulata, perforata, carinata, tota scaberrima, fusca, suprà fasciata: spira pyramidata elevata; sutura distincta, impressa; anfractibus convexis; ultimi carina acuta, distincta, supra marginata sc. sulco expressa vel exarata; omnibus granulis distinctissimis, conferitis, asperrimis scobinatis et quasi echinulatis; umbilicus parvo, sub-spirali, aperto; apertura rotundata; peristomate continuo, circinato, disjuncto, reflexo. Axis 2 lin. Diam. 2½. Anfr. 6.

Diagnostic features of the shell

Shell as in the genus description. The main diagnostic feature is the presence of only one keel along the body whorl. The overall shape of the shell of H. echinulata is always conical but not scalariform as in H. bicarinata. The whorls are rounded and lack the typical “shoulder”. The sutures are deep, but less deeply marked than in H. bicarinata (see Figs 79–82).

Figures 79–82. 

Shells of Hystricella echinulata. 79–80 Terra Chã 81 S slope of Pico Banco 82 steep path from Pico Branco to Terra Chã. Scale bar 1 mm.

Measurements

D 5.2 ± 0.3 mm (range 4.6–5.8 mm); H 4.8 ± 0.5 mm (range 4.3–5.0 mm); FW 2.5 ± 0.2 mm; PA 42.6 ± 8.3; DU 0.5 ± 0.08 mm; NT 23 ± 9; NW 5.6 ± 0.1 (n = 40). Ratio D/H 1.1; ratio FW/H 0.5.

Body

Body as in the genus description. The colour of the head and the neck is somewhat darker than in H. bicarinata.

Genital anatomy

As in the genus description. Main diagnostic features are as follows. The free oviduct is usually very short and four times shorter than the vagina. The penial flagellum is usually as long as the epiphallus. It has a remarkably cylindrical shape and a blunt apex. Its internal walls are completely smooth, without any papillae. The genital atrium is always elongated. See Figs 83–93.

Figures 83–93. 

Anatomy and genitalia of Hystricella echinulata. Terra Chã: 83 whole genitalia excluding gonads 84 ornamentation of the inner walls of the distal penis, the distal vagina and the genital atrium 85 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium 86 penial papilla 87 whole genitalia excluding part of OSD, AG and gonads 89 penial papilla and ornamentation of the inner walls of the flagellum 91 mantle border 92 section of penial papilla. Faja Pequena: 88 section of vagina 90 jaw 93 whole genitalia excluding gonads. Scale bars 1 mm.

Ecology

Hystricella echinulata is recorded from low (20 m a.s.l.) to relatively high altitudes (450 m a.s.l.). Except for the slightly higher altitudinal range, this species shares the same ecology as H. bicarinata; it is commonly found under volcanic rocks scattered on grassland in open fields that are usually sloping. It has also been found in cracks and crevices or among scree on steep slopes.

Distribution

Hystricella echinulata is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal). The species is restricted to the northeastern, mountainous part of the island and present only in the Pico Branco-Terra Chã massif area. It is commonly found along Faja Pequena and the ridge and the south-exposed slope eastwards of Terra Chã (Fig. 94). No populations are known from the offshore islets.

Figure 94. 

Distribution of Hystricella echinulata.

Comparison and comments

See under H. bicarinata and/or the section on putative hybrids of H. bicarinata and H. echinulata above.

Status and conservation

According to Seddon (2011b) the species is Least Concern (LC), but in our opinion, the species should be considered as Endangered (EN B1a, b(i, ii, iv), 2a, b(i, ii, iv)) because its area of occupancy and extent of occurrence is less than 8 km2 and because it is mostly restricted to the highest elevations in the north-eastern part of Porto Santo and only occurs at scattered and isolated places with suitably humid microclimates. Mayor threats to the species include an observed decline of suitable habitats, extent of occurrence and area of occupancy over the past 30 years, i.e. as the result of longer drought periods which are possibly associated with effects of climate change, an increase of fire incidents, grazing by goats and to a lesser extent also hiking as tourism is increasing on Porto Santo. As most of the known localities are concentrated in the Pico Branco-Terra Chã area in the north-easternmost part of Porto Santo (Fig. 94), we consider that the species is not present at more than five locations.

Hystricella echinoderma (Wollaston, 1878)

Figs 95, 96

List of synonyms

1878 Helix (Hystricella) echinoderma Wollaston: 159–160.

1894 Geomitra echinoderma – Pilsbry in Pilsbry 1893–1895: 242.

1931 Geomitra (Actinella) echinoderma – Nobre: 88.

1950 Discula (Hystricella) echinodermaMandahl-Barth 1950: 31, 55.

1983 Discula (Hystricella) echinoderma – Waldén: 267.

2002 Geomitra echinoderma – Bank et al.: 124.

2008 Hystricella echinoderma – Seddon: 80.

Type material

NHM 1875.02.02-52, lectotype (herewith designated) from loc. typ.; NHM 1875.02.02-53 to -54, 2 paralectotypes, from loc. typ.

Locus typicus

Portum Sanctum, semifossilis; recens haud observata.

Original description

From Wollaston 1878: T. trochiformis, subtus subplanulata perforata, undiquegranulis magnis obtusis sat dense obsita; spira elevata; anfractibus convexis, subgibbosis, ultimo subtectiformi acute carinato (carina simplici, solum antice gradatim obsolete subduplici); umbilico punctiformi, aperto; apertura subovali-rotundata, labris continuis conjunctis, peristomate simplici, expanso, subrecurvo, tenui, relevato. – Long. axis 2 ½ lin.; diam. 3 ½.

Description of the lectotype

Shell large for the genus, with 6¾ regularly increasing whorls, the protoconch with 1.9 whorls. The form of the shell is high conical, the convex to quadrangular teleoconch whorls showing two more and more expressed angulations which form in the last whorl two rounded keels, the upper less developed than the lower one. The last whorl measures 59%, the penultimate whorl 14% of the total shell height. The lower 70% of the body whorl are situated below the peripheral keel which is slightly constricted by a concavity below the periphery in frontal view. The base is convex, slightly straightening towards the umbilicus. The two keels of the body whorl are located in the upper ⅛ and ⅓ of the total height of the body whorl. The suture between the whorls is simple but deeply sunken. The aperture, which is inclined to the vertical axis of the shell in an angle of 48° and descending in the last 5% of the last whorl in an angle of 38° to the horizontal axis, has an oblique-ovate form, its width amounts to 43% of the total shell width, its height to 34% of the total shell height. It has a slightly reflected lip, which is completely detached from the body whorl. The centered umbilicus, which measures 10% of the shell’s total width, is in the last whorls circular, but completely closed deeper inside. The protoconch is smooth, the teleoconch shows a number of oblique radial ribs, 15 in the penultimate quadrant of the body whorl, and is additionally covered by numerous irregularly arranged, elongate, rough tubercles. The number of tubercles in the standard-quadrate of the base is 81. There are no traces of colouration. See Fig. 95.

Figure 95. 

Lectotype of Hystricella echinoderma, NHM 1875.02.02-52. Scale bar 1 mm.

Measurements

D 7.0 mm; H 5.9 mm; FW 3.5 mm; PA 42.2°; DU 0.5 mm; NT ≈ 35; NW 6.6 (n = 1). Ratio D/H 1.2; ratio FW/H 0.5.

Distribution

Hystricella echinoderma is only known from Fonte da Areia in the northern part of Porto Santo (Fig. 96).

Figure 96. 

Distribution of Hystricella echinoderma.

Comparison and comments

Hystricella echinoderma can be confused on first glance with comparatively large-sized species of the genus Wollastonia like W. vermetiformis, W. ripkeni sp. n., and W. falknerorum sp. n.; from these it is distinguishable by the lack of one or two sharply pointed keels, respectively, a much rougher sculpture, a non-eccentric umbilicus, and the stepped, high conical form. From the similarly sized W. subcarinulata and W. inexpectata sp. n. it is separated by a wider or non-eccentric umbilicus, a relatively higher shell, the quadrangular instead of convex rounded whorls, a coarser granulation and the oblique-ovate instead of straight horizontally elliptical aperture. From the similar shaped H. echinulata and H. microcarinata sp. n. it is easily distinguishable by the much larger size.

Taxonomic remarks

Wollaston (1878) compares H. echinoderma with the rather similar H. echinulata and calls it a monstrous sister species of that species, citing as examples of pairs of nominal species with a distinct size difference Helix vermetiformis and H. bicarinata, H. Lowei and H. portosanctana as well as H. bowdichiana and H. punctulata.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Wollastonia gen. n.

Remarks

The synonymy is the same as for the genus Hystricella (see above).

Type species

Helix [Helicella] turricula R. T. Lowe, 1831 – herewith by original designation.

Included taxa

Wollastonia turricula (R. T. Lowe, 1831), comb. n., W. vermetiformis (R. T. Lowe, 1855), comb. n., W. ripkeni De Mattia & Groh, sp. n., W. falknerorum Groh, Neiber & De Mattia, sp. n., W. leacockiana (Wollaston, 1878), comb. n., W. beckmanni De Mattia & Groh, sp. n., W. jessicae jessicae De Mattia, Neiber & Groh, sp. n., W. jessicae monticola De Mattia, Neiber & Groh, ssp. n., W. klausgrohi De Mattia & Neiber, sp. n., W. oxytropis (R. T. Lowe, 1831), comb. n., W. subcarinulata (Wollaston, 1878), comb. n., W. inexpectata De Mattia & Groh, sp. n.

Description of the genus

Shell. The shell is dextral and hairless. Its shape can be very variable, from conical, elongated and scalariform with deep sutures to rather flattened, with very shallow sutures. The protoconch is from whitish to completely dark brown with 1.5 to 2.5 whorls. It is almost smooth along the first whorl and shows fine radial striae and extremely small, scattered tubercles along its remaining portion. The teleoconch has from 4.3 to 7.0 rapidly increasing whorls. It is usually dark brown with brick-red and/or dark violet shades in colour. The dark areas of the shells are mottled with more or less light brown to whitish areas, usually placed longitudinally and slightly slanting. In some species, the lighter areas tend to be more evident along the keel. No band pattern is visible along the upper whorls. On the lower part of the last whorl two dark, more or less broad bands may be present. In some specimens, the two bands merge together forming a single wide, dark band. Sometimes the bands are interrupted by yellowish to whitish sections. The area around the umbilicus is usually the lightest in colour. Some species are usually covered entirely with soil or sand grains which probably serve as a camouflage.

The spire is very variable in height, ranging from flattened, almost discoidal to slender and remarkably conical in shape. The number and the extent of the keels are variable from species to species. Some species have one or two distinct keels starting already from the second whorl of the teleoconch, while others have a single, more or less strong keel only along the last whorl. Some species have a lower, distinct principal keel somewhat protruding the body whorl, with an upper secondary and much less evident keel. The whorls can be either convex or flat. In some species, the whorls form a “shoulder”, giving the whorls and angular contour. The sutures are usually deep, even if in some species they may also be rather shallow.

The external surface has from very fine to strong, clearly visible, irregularly spaced, growth lines. Irregularly disposed tubercles are found all over the teleoconch. The dimensions and the arrangement of these tubercles varies considerably from species to species, from large and scattered tubercles to a very dense pattern of small papilla-like tubercles all over the shell. In the species with larger tubercles, these are somewhat denser along the keels of the penultimate and last whorls, giving to the keel(s) the appearance of (a) rough chord(s). The last whorl is usually large, descending near the aperture with a contribution ranging from 40% to 60% of the total shell height. The umbilicus is open but very narrow, either concentric or eccentric, and measures approximately 10% of the maximum shell diameter. The aperture is elliptical with a faint thickening along the columellar portion of the aperture. Sometimes this thickening can also extend as far the parietal side of the aperture. The peristome is continuous, slightly to evidently reflected, with the columellar margin somewhat thicker and more reflected.

The shells of the species belonging to Wollastonia gen. n. show a remarkable plasticity, with regard to dimensions, shape and ornamentation. This variability undoubtedly exceeds that of the genus Hystricella. Thus, for each taxon, the shell’s features will be described in detail.

Body. The head and neck are usually dark grey to grey. The sides and the posterior upper section of the foot are whitish. In some species, the pigmented ommatophoral retractor muscles are visible through the skin of the back of the cephalic area. The foot is white and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral areas are equipped with bands of muscles roughly arranged in a chevron pattern. The mantle border is grey to dark grey with five more or less developed lobes. The ratio of lateral to the dorsal lobes varies from specimen to specimen, also in the same population. In some specimens one of these lobes (either lateral or dorsal) may be totally missing. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible. The jaw is odontognathous and very variable in shape, from almost straight to markedly arched. There are many transversal, smooth ridges, ranging from eight to 25 in number. The right ommatophoral retractor is independent from both penis and vagina.

Genitalia. The general arrangement of the genitalia is semi-diaulic monotrematic. A convoluted to almost straight hermaphroditic duct arises from a multi-lobated gonad. The albumen gland is long and thin and connected to a variably long sperm-oviduct consisting of a prostatic and a uterine portion. The prostatic part extends into a thin vas deferens, roughly as long as the sperm-oviduct, and terminating in the penial complex. The distal portion of the uterine part extends into the free oviduct and turns into a vagina along its course at the level of the duct of the bursa copulatrix. The free oviduct can be as long as the vagina or also three to four times longer. The duct of the bursa copulatrix is usually wide, approximately as long as the penis and uniform in diameter. It extends into a variable, oval to roundish bursa copulatrix. In some species, the transition area between the duct and the bursa itself is not very distinctly delimited; the duct more or less abruptly widens and transforms into the bursa. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. The glands have usually two or three, approximately equally long and very rarely bifurcated branches. A short and thin vaginal appendix arises from the vagina’s wall, immediately distal of the glandular tuft. Very smooth, rather wide, and little elevated, irregularly spaced pleats run longitudinally along the inner surface of the vagina, reaching into the genital atrium as far as the genital orifice. The atrium can be short and wide or long and thin. Its internal walls can either be smooth or with large and soft pleats running longitudinally as far the genital orifice. The penial complex consists of a flagellum, an epiphallus (which extends from the insertion of the vas deferens to the penial retractor muscle) and a penis that inserts into the atrium. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus. In one species, W. oxytropis, the flagellum is very short (¼ of the epiphallus) but remarkably pointed. The internal walls of the flagellum can be either completely smooth or, in one species, can have a digitiform, pointed papilla originating from the proximal end of the flagellum and orientated toward the penial papilla. The epiphallus is usually short to moderately long. Its internal walls have a variable number of longitudinal pleats that can be more or less developed and elevated. The retractor muscle is large, strong and is of a variable length. The penis lacks a muscular or glandular sheath. It is thick-walled and approximately four times longer than the flagellum. It is usually cylindrical to sometimes slightly swollen in its distal part. Sometimes, a thin sheath consisting of connective tissue envelops the distal penis, causing a partial and longitudinal minor compression. The inner walls of the penis are smooth or with irregular and spaced pleats, which run longitudinally and reach the genital atrium. The section where the penial papilla is located is usually detectable from the outside by virtue of a fine circular swelling corresponding to the origin of the papilla. The penial papilla is usually small, reaching maximally ⅛ of the total penial length and is conical to subcylindrical in shape. It has smooth external walls with the opening emerging apically. The penial papilla channel is thin and narrow. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue, which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inwards.

Jaw and radula. As for the genus Hystricella, no notable variability was found among the species of the genus Wollastonia gen. n. and the two genera share almost an identical jaw-radular apparatus. The jaw is odontognathous, arched and with rough wrinkles (irregular ribs). The radula ribbon is typical helicoid, it is elongated but not very slender. A central tooth is present, tricuspid, the main cusp (endocone) is rhomboid, pointed; the ectocones are much smaller than the endocone, they are triangular, pointed. There are 19–20 laterals and marginals, which do not distinctly differ from each other. Their shapes rather change gradually from the first laterals towards the marginals. Laterals are bicuspid, with rhomboid or triangular and pointed endocones. The ectocones are much smaller, pointed, and triangular. The endocones of the central and first laterals are approximately of the same size. Both the endocone and the ectocone of the laterals gradually become bifurcated towards the marginal teeth, but the ectocones occasionally might have three cusps as well. The cusps of the marginals are gradually decreasing in size; therefore, the outermost marginals appear serrated. The jaw is variable in shape: from almost straight to markedly arched. There are many transversal and smooth ridges, ranging from 13 to 20. For Wollastonia jaws and radulae, see Fig. 98.

Distribution

The genus Wollastonia is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal) and some surrounding islets (Fig. 97). Along the eastern part of the main island, the genus is restricted to the southern mountainous part. It is patchily distributed from the hilly area east of Vila Baleira towards the east to Portela, Zimbreiro and along the highest southern peaks of Porto Santo, namely Pico do Maçarico and Pico do Baixo as far as Ponta da Galé. It is also present along the eastern coast area of Pico do Concelho. Along the western part of Porto Santo, Wollastonia is found on Pico de Ana Ferreira. With regard to the surrounding offshore islet, Wollastonia is present on Ilhéu de Cima and Ilhéu de Cenouras at the eastern and Ilhéu de Ferro at the western end of the island. Subfossil representatives of the genus are found mainly in the mud and aeolinite deposits along the southeastern (Vale do Touro, Ponta do Passo, Barbinha, Calhau da Serra de Fora) and northern (Fonte da Areia) coasts. Wollastonia may be older than Hystricella as suggested by the somewhat deeper divergences in the molecular trees (Fig. 3).

Figure 97. 

Distribution of the genus Wollastonia gen. n. Filled circles refer to recent and open circles to fossil records.

Figure 98. 

Jaws and radulae Wollastonia gen. n. A W. leacockiana Pico de Ana Ferreira B W. oxytropis Pico do Concelho C W. jessicae jessicae sp. n. Vale do Touro.

Ecology

Representatives of the genus Wollastonia are commonly found under volcanic rocks scattered on grassland in open fields and more or less steep mountain slopes. Specimens aestivate on the lower surfaces of the rocks, frequently forming clusters of individuals attached to one another.

Etymology

Named to honour the late British malacologist and entomologist Thomas Vernon Wollaston for his indispensable contributions to the taxonomy and nomenclature of the terrestrial snails of the mid-Atlantic islands.

Taxonomic remarks

The genus Wollastonia gen. n. is separated here from Hystricella both upon molecular and morphological features. Moreover, the analysis of the distribution of its species supports this view.

The phylogenetic analyses recovered three clades, in which morphologically mostly similar species were grouped together and that were supported in at least two of the analyses. The clade including recent species hitherto assigned to Hystricella (except H. bicarinata and H. echinulata), supported in the BI and MP analyses (Figs 3, 5), are here regarded as representing a new genus, Wollastonia gen. n., because representatives of the morphologically distinct Callina species are interspersed between Wollastonia gen. n. and Hystricella in the strict sense receiving significant/meaningful support in the BI and MP analyses of the cox1 data alone and the concatenated mitochondrial and nuclear data. This clade includes the recent species W. leacockiana comb. n., W. turricula comb. n., and W. oxytropis comb. n. as well as three additional recent taxa that will be formally described below: W. klausgrohi sp. n., W. jessicae sp. n., and W. jessicae monticola ssp. n. (Fig. 5). The relationships of most of the taxa within Wollastonia gen. n. could, however, not be well resolved (Fig. 5) on the basis of the phylogenetic analyses of the cox1 data.

Shell size and shape are remarkably more variable in the genus Wollastonia as compared to Hystricella. Most of the Wollastonia gen. n. species have the shell surface covered with small and very dense tubercles that can be compared to a very fine granulation. The typical Hystricella’s “spiny” contour (Lat.: hystrix = spiny, deriving form Greek ὕστριξ (hústrix = porcupine) is replaced by a smoother one.

The genital morphology of the two genera shows no substantial differences. Nevertheless, some Wollastonia gen. n. species present a higher degree of complexity with regard to the inner ornamentation of the atrium and the flagellum. Structures such as more or less developed pleats, fleshy pads and/or fringes are found in Wollastonia gen. n. that are never present in Hystricella.

The distribution ranges of Hystricella and Wollastonia gen. n. are separated and not considerably overlapping. Wollastonia colonises the southern and southwestern parts of Porto Santo, whereas Hystricella is currently found exclusively in the central and northern parts.

Most of the morphological characters that clearly distinguish Hystricella from the other native Geomitridae of Porto Santo are also valid for Wollastonia. gen. n., e.g. the continuous and detached peristome and the shape of the penial flagellum that is always short and with a remarkably blunt apex (except in W. oxytropis stat. n.). For remarks on the differentiating features, see the respective section in the re-description of the genus Hystricella above.

Wollastonia turricula (R. T. Lowe, 1831), comb. n.

Figs 99–102, 103–111, 112

List of synonyms

1831 Helix turricula R. T. Lowe: 58, pl. 6 fig. 21.

1846 Helix turricula – L. Pfeiffer: 141, pl. 91 figs 5–7.

1847 Helix turricula – L. Pfeiffer in L. Pfeiffer 1847–1848: 190.

1854 Helix turricula – Reeve in Reeve 1851–1854: pl. 138 fig. 867.

1854 Helix (Ochthephila) turricula – Albers: 37, pl. 9 figs 11–13.

1855 Helix (Hystricella) turricula – R. T. Lowe: 186.

1867 Helix (Octephila) turricula – Paiva: 47.

1878 Helix (Hystricella) turricula – Wollaston: 163-165.

1878 Helix (Hystricella) turricula var.ß pererosa Wollaston: 165.

1888 Helix turricula – Tryon in Tryon and [Pilsbry] 1888: 33, pl. 7 fig. 91.

1894 Geomitra bicarinata – Pilsbry in Pilsbry 1893–1895: 242.

1923 Ochthephila turricula – Watson: 283–293, pl. 6 figs 1–10.

1931 Geomitra (Actinella) bicarnata – Nobre: 88, fig. 38.

1950 Discula (Hystricella) turricula – Mandahl-Barth: 31, 55.

1950 Discula (Hystricella) turricula pererosa – Mandahl-Barth: 31, 55.

1977 Discula (Hystricella) turricula – Pettitt: 147–150.

1983 Discula (Hystricella) turricula – Waldén: 267.

2002 Geomitra turricula – Bank et al.: 124.

2008 Hystricella turricula – Seddon: 79, pl. 29 fig. b, map 181.

2009 Hystricella turricula f. pererosa – Groh et al.: 21 fig. 28.

2011 Hystricella turricula – Seddon: e.T6723A12800477.

Type material

[turricula], NMH 1968.578, lectotype (herewith designated), from loc. typ., ex coll. R. T. Lowe; NMH 1948.7.8.35, 1 paralectotype, from loc. typ., ex coll. R. T. Lowe. The original figure of Helix turricula R. T. Lowe, 1831 (from Lowe 1831: pl. 6 fig. 21) is depicted in Fig. 99, the lectotype (Phot. P. Crabb, NHM) in Fig. 100; [pererosa], RAM EXEMS-1720-1909-d39-74a, lectotype (herewith designated), from loc. typ., ex coll. Linter, ex coll. T. V. Wollaston; RAM EXEMS-1720-1909-d39-74b, 1 paralectotype, from loc. typ., ex coll. Linter, ex coll. T. V. Wollaston (see Figs 113–115).

Loci typici

[turricula], Hab. in Insula quadam «Ilheo de Cima» dicta, juxta Insulam Portum Stum; [pererosa], ‘Ilheo de Cima’.

Further material examined

All from Porto Santo. Fossil: CKG/10, CWDM/2, ZMH 116090/1 fragm [ex coll. E. Clauss], Quaternary slope deposits at the SW coast of the Ilhéu de Cima, 33°03'15"N/16°17'02"W, 40 m, leg. K. & C. Groh & J. & C. Hemmen, Jun. 26 1983 and leg. J. Gerber, K. Groh & J. Hemmen, Aug. 17 1985. Recent: CKG/9, Ilhéu de Cima, top, under stones, 33°03'13"N/16°16'48"W, approx. 100 m, leg. K. & C. Groh, Oct. 25 1980; CKG/7, CMN/29, ANSP H 11918/42, ZMH 120611/1 [ex coll. W Fauer], Ilhéu de Cima, top, under stones, 33°3'13"N/16°16'48"W, approx. 100 m, leg. K. & C. Groh & J. & C. Hemmen, Jun. 26 1983; ANSP H 11918/17, Ilhéu de Cima, top, under stones, 33°3'13"N/16°16'48"W, approx. 100 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 17 1985; ZMH 24296/1, Porto Santo, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn; ZMH 24297/1, Porto Santo, without exact locality data, ex coll. Museum Klagenfurt; ZMH 24298/1, Porto Santo, without exact locality data, ex coll. Altonaer Museum.

Original descriptions

[turricula]: From Lowe 1831: H. testa turrita, pyramidata, sub-cylindrica, bicarinata, perforata, tota minute et confertissime granulata, fusca, fere unicolore, vel supra obsolete fasciata: spira valde elevata, obtusissima; sutura distincta; anfractibus bicarinatis, carinis æqualibus, prominentibus, distinctis, sulco divisis: apertura rotunda; peristomate continuo, circinato, disjuncto, tenui, reflexo. Axis 4 lin. Diam. 3. Anfr. 8–8½; [pererosa]: From Wollaston 1878: ... a keel, very largely developed in the ‘α. pererosa,’ in the centre of each, causing the basal volution to be strongly bicarinated ….. var. ß. pererosa. – Plerumque obscurior, spira breviore, anfractibus in medio multo grossius carinatis (carina altissima), ultimo sensim latiore necnon antice obsolete subtortuoso, fere quasi superimposito, apertura submajore.

Redescription of the shell

The shell is dextral and hairless. It is remarkably elongated and scalariform with deep sutures. The protoconch is from whitish to completely dark brown with 1.5 to 2 whorls. It is finely granulated along the first whorl and shows also fine radial striae and extremely small, scattered tubercles along its remaining portion. The teleoconch has from 6.9 to 7.2 rapidly increasing whorls. It is usually reddish brown, with brick red and/or dark violet shades in colour. The dark areas of the shell are mottled with more or less light brown to whitish areas, usually placed longitudinally and slightly slanting. In some specimens, the lighter areas tend to be more evident along the keels. No band pattern is visible along the upper whorls. On the lower part of the last whorl there is sometimes one dark, indistinct band that is usually very narrow. The area around the umbilicus is usually the lightest in colour. The shell is usually covered by fine debris serving as a camouflage.

The spire is very high and remarkably conical in shape. Two evident keels start already from the second whorl of the teleoconch. The keels gradually strengthen, reaching their maximum extent along the body whorl. The lower and the upper keel are more or less equally developed, the lower only sometimes slightly more pronounced. The lower whorls (especially the fourth and fifth) form a “shoulder” giving the whorls an angular contour. The sutures are deep and well marked.

The external surface does usually not show fine growth lines, except for some strong, more or less regularly spaced ribs along the top and bottom of the body whorl. Irregularly arranged, fine tubercles are present all over the teleoconch, also along the edges of the keels the tubercles remain well-separated not forming a peripheral chord.

The last whorl is not distinctly wider than the penultimate whorl, nevertheless abruptly descending near the aperture. The umbilicus is very narrow, almost closed, and somewhat eccentric. The aperture is elliptical with a faint thickening along the columellar portion of the stoma. Sometimes this thickening can also extend as far as the parietal side of the aperture. The peristome is continuous and detached from the body whorl, reflected, with the columellar margin somewhat thicker and more distinctly reflected (Figs 101–102).

Figures 99–102. 

99 Wollastonia turricula original figure as in R. T. Lowe, 1831 (from Lowe 1831: pl. 6 fig. 21). Shell of Wollastonia turricula 100 shell of the lectotype from loc. typ., ex coll. R. T. Lowe NMH 1948.7.8.35 101, 102 shells from Ilhéu de Cima. Scale bar 1 mm.

Measurements

D 6.6 ± 0.4 mm (range 6.1–7.0 mm); H 8.8 ± 0.2 mm (range 6.1–9.0 mm); FW 4.3 ± 0.1 mm; PA angle 32.1 ± 2.1°; NT > 100; NW 7.0 ± 0.1 (n = 8). Ratio D/H 0.8; ratio FW/H 0.5.

Body

The head and the neck are usually dark grey to grey. The sides and the posterior upper section of the foot are whitish. The foot is white and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral areas are equipped with bands of muscles that are roughly arranged in a chevron pattern. The mantle border is dark grey with five more or less developed lobes. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible. The jaw is odonthognatous and its shape is markedly arched. There are up to 25 smooth transverse ridges. The right ommatophoral retractor is independent from both penis and vagina.

Genital anatomy

The albumen gland is short and as long as the sperm-oviduct. The prostatic part of the sperm-oviduct extends into a vas deferens that is approximately as long as the sperm-oviduct, which is inserting into the penial complex. The free oviduct is two times longer than the vagina. The duct of the bursa copulatrix is rather wide, slightly shorter than the penis, and uniform in diameter. It terminates in a roundish bursa copulatrix. The transition area between the duct and the bursa is very sharply delimited, abruptly widening and turning into the bursa. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually two rather wide glands that are approximately equally long and very rarely branched. A short and thin vaginal appendix arises from the wall of the vagina, just distal of the glandular tuft.

Very smooth, rather widely and irregularly spaced and little elevated pleats run longitudinally along the inner surface of the vagina, reaching into the genital atrium as far as the genital orifice. The atrium is rather wide. Its internal walls are equipped with large and soft pleats, running longitudinally towards the genital orifice. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus. Its internal walls are equipped with a digitiform papilla that originates at the proximal end of the flagellum and which is orientated towards the penial papilla. The epiphallus is approximately half as long as the penis. Its internal walls are usually equipped with two to three longitudinal pleats. These pleats are arranged more or less “metameric”.

The retractor muscle is large, strong and is of variable length. The penis lacks any muscular or glandular sheath. It is thick-walled and approximately four times longer than the flagellum. It is cylindrical and slightly swollen in its proximal portion. The inner walls of the penis are equipped with a large longitudinal, fleshy, and smooth pleat, running from the penial papilla almost as far as the atrium. Some minor, smooth, longitudinal pleats are usually also present. The penial papilla is short but somewhat bulky. Its surface is smooth, with the opening emerging apically; its channel is rather narrow. The inner lumen of the penial papilla is filled with a spongy and sturdy tissue, which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward. See Figs 103–111.

Figures 103–111. 

Anatomy and genitalia of Wollastonia turricula, Ilheu de Cima. 103 whole genitalia excluding gonads 104 mantle border 105 section of vagina 106 whole genitalia excluding part of OSD, AG and gonads 107 ornamentation of the inner walls of the flagellum 108 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium 109 longitudinal section of penial papilla 110 section of penial papilla 111 tip of penial papilla. Scale bars 1 mm.

Ecology

Wollastonia turricula is found under volcanic rocks scattered on grassland in open fields.

Distribution

Restricted to the slopes and plateau of the islet Ilhéu de Cima, off the southeastern coast of Porto Santo. The species occupies an area of less than two square kilometres (Fig. 112). The form pererosa of W. turricula is known to occur on the steep slopes at lower elevations of the islet Ilhéu de Cima.

Figures 112–116. 

112–114 shells of Helix turricula var. pererosa RAM EXEMS-1720-1909-d39-74 115 Ilheu de Cima 116a, 116b labels from RAM. Scale bar 1 mm.

Comparison and comments

Wollastonia turricula is easily distinguishable from all the species belonging to either Hystricella or Wollastonia gen. n. by its peculiarly turreted shell and genital features. The anatomical and genital features of the species, under the name Ochtephila turricula, have previously been thoroughly described by Watson (1923), nevertheless Watson’s study limited its observations mostly to the external features of the genital system. Unfortunately, except for some drawings presented by Mandahl-Barth (1950), no additional information on the genital anatomy was published until now. Watson’s (1923) description, despite being thorough and accurate, sometimes gives a wrong impression of what the author observed. On p. 289 the author describes “three small finger-shaped processes” pointing out that “the shortest of the three is usually less than half the length of the others”. He considered all these three processes “homologous with the so called mucous glands found in so many of the Helicidae”. Watson considered also the vaginal appendix as a gland that is probably an apomorphic state of the stylommatophores. He also wrongly considered the “conspicuous hemispherical swelling” on the outer side of the vagina to be “doubtless a degenerate dart-sac”. It is known that the dart sac can assume such a “swollen” appearance, as for example in the genus Cernuella, but its inner structure shows a totally different arrangement compared to that found in W. turricula (see Giusti et al. 1995: 445). Watson also described the internal ornamentation of the penis as “smooth”, not detecting the main fleshy pleat and its surrounding secondary small pleats. Nevertheless, Watsons’ (1923) description as a whole is thorough and accurate, including also interesting notes about the histology of the tissues. This kind of anatomical description was very rare at the time, where conchological features were still considered as the most important taxonomical characters in land snail systematics.

Taxonomic remarks

After its description, the taxon Helix turricula var. pererosa Wollaston, 1878 was mostly ignored by subsequent authors, except by Mandahl-Barth (1950) who treated it as a subspecies of W. turricula. Three syntypes of Helix turricula var. pererosa Wollaston (see Figs 112–114) could be traced at the Exeter Museum (coll n°EXEMS-1720-1909-d39-74). The preservation of the specimens clearly indicates that they were collected alive and not as subfossils. Following a careful morphological evaluation and a comparison with recent and subfossil specimens (Fig. 115), no substantial morphological differences could be detected with regard to the shell morphology, both concerning its micro- and macroscopic features (microsculpture, overall shape, keels, dimensions). Therefore, we treat it here as just a form of Wollastonia turricula and propose the name Helix turricula var. pererosa Wollaston, 1878 as a junior synonym of Wollastonia turricula. Pettitt (1977) reports on significant changes in the shell shape of W. turricula after the construction of the lighthouse on the islet Ilhéu de Cima after 1900. However, that observation may be based on material collected prior to the construction works and therefore may have contained more specimens of the form pererosa because the top of the islet was only easily accessible after the construction of the stairs to the lighthouse and therefore collecting probably was carried out nearer to the coast where the pererosa form predominates.

Status and conservation

According to Seddon (2011e) the species is Vulnerable (VU). In our opinion, however, it should be regarded as Critically Endangered (CR B1a, b(ii, v), 2a, b(ii, v)) because the extent of occurrence and the area of occupancy of the species is less than 1 km2 and although Watson (1923) reported the species to “occur in considerable numbers” on Ilheu de Cima, observations made during the 1980s (KG) showed that the species is considerably less frequent than in the past, probably as the result of a decline of habitat quality as a consequence of grazing by goats or other unknown reasons (see also Seddon (2008: 80)). Moreover, living specimens were only reported from the area around the top plateau of Ilheu de Cima, i.e., at a single location (Fig. 117).

Figure 117. 

Distribution of Wollastonia turricula. Filled circles refer to recent and open circles to fossil records.

Wollastonia vermetiformis (R. T. Lowe, 1855), comb. n.

Figs 118–120

List of synonyms

1855 Helix (Hystricella) vermetiformis R. T. Lowe: 186.

1867 Helix (Octephila) vermetiformis – Paiva: 47–48.

1867 Helix (Octephila) vermetiformis var.α minor Paiva: 48.

1878 Helix (Hystricella) vermetiformis – Wollaston: 163.

1894 Geomitra vermetiformis – Pilsbry in Pilsbry 1893–1895: 242.

1931 Geomitra (Actinella) bicarinata var. vermetiformis – Nobre: 87.

1950 Discula (Hystricella) vermetiformis – Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) oxytropis vermetiformis – Waldén: 267.

2002 Geomitra vermetiformis – Bank et al.: 124.

2006 Discula oxytropis – Cameron et al.: 40 [partim].

2008 Hystricella oxytropis – Seddon: pl. 29 fig. C, map 177 [partim; in her “Corrigenda” Seddon (2009) mentions for pl. 29 fig. C in Seddon (2008) that the ”Shell of Hystricella oxytropis is normally approx. 8 mm wide, not 5 mm, and does not always have a double keel”].

2009 Hystricella oxytropis – Seddon: 80 [partim].

2009 Hystricella vermetiformis vermetiformis – Groh et al.: 21, fig. 29.

2017 Hystricella vermetiformis – Groh: e.T107396913A107396917.

Type material

NHM 1968.588, lectotype (herewith designated), from loc. typ. ex coll. R. T. Lowe. The lectotype is depicted in the Fig. 118.

Figures 118–120. 

Shells of Wollastonia vermetiformis. 118 lectotype of Helix vermetiformis R. T. Lowe, 1855, NMH 1968.588 ex coll. Lowe 119 recent specimen from Pico do Baixo 120 subfossil specimen from Porto dos Frades. Scale bar 1 mm.

Locus typicus

[vermetiformis] “Hab. fossilis in Portu Sto” (= Porto Santo, fossil); [minor] rara ad Zimbral d'Aréa [= Zimbral da Areia (at the SE coast of Porto Santo, N of Barbinha-Porto dos Frades), 33°04'25"N/16°17'46"W].

Additional material

All from Porto Santo. Fossil: CWDM/4, Barbinha, a little distance south along the old rough road, mud fossil deposits, 33°03'56"N/16°17'49"W, 10 m, leg. W. De Mattia & J. Macor, May 2015; CKG/3, W coast, Ribeiro de Agua, 33°02'11"N/16°23'34"W, 50 m, leg. C. Groh, Jul. 27 1983; CKG/1, approx. 800 m E Vila Baleira, approx. 60 m N of oil tanks at bridge over Vale do Touro, from Quaternary tuffite layers, 33°03'51"N/16°19'20"W, 30 m, leg. K. Groh & J. Hemmen, Jul. 27 1983; CKG/1, Ponta da Canaveira, Quaternary aeolinites, 33°02'30"N/16°23'35"W, 50 m, leg. K. Groh & J. Hemmen, Jun. 24 1983; CKG/10, between Porto dos Frades and Ferreira Grande, approx. 300 m N sand pit, 33°04'28"N/16°17'42"W, 25 m, leg. K. Groh & J. Hemmen, Jun. 24 1983; CKG/1, Barbinha, uppermost light Quaternary aeolinite layer, 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh & J. & C. Hemmen, Jun. 24 1983; ANSP H 11919/21, Barbinha, Quaternary aeolinites, 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 7 1983; ZMH 110125/34, coastal slopes at road from harbour to Porto Santo [Vila Baleira], 33°03'48"N/16°19'17"W, c. 10–50 m, leg. E. Clauss, Sep. 22 1992; ZMH 110139/23, coastal slopes at road from harbour to Vila Baleira, 33°03'48"N/16°19'17"W, c. 10–50 m, leg. E. Clauss, Sep. 22 1992; ZMH 110104/5, coastal slopes in the SE to E coast of Porto Santo, 33°03'46"N/16°18'21"W, c. 10–50 m, leg. E. Clauss, Jun. 1 1996; ZMH 24295/1, Madeira archipelago, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn. Recent: CKG/1, W slope of Pico do Baixo, in a rock crack, 33°03'47"N/16°17'58"W, approx. 125 m, leg. K. Groh & J. Hemmen, Jun. 9 1983; CKG/2, Ilhéu das Cenouras, 33°06'12"N/16°17'20"W, 20 m, leg. K. Groh & J. Hemmen, Jul. 2 1983.

Original description

[vermetiformis]: From Lowe 1855: T. anguste umbilicata distincte bicarinata pyramidato-conoidea solidula crassiuscula utrinque granulata; spira elevata anfractui ultimo quasi superimposita, carina inferiore suturae distinctæ superincumbente; anfr. 7–7½ planiusculis conspicue bicarinatis, carina inf. prominente sulco infra exarata, ult. antice valde deflexo; umbil. parvo; apert. ovali-rotundata circinata, labris continuis conjunctis; perist. undique soluto relevato tenui acuto. Diam. major 8½–9, min. 8¼–8¾, alt. 7–8½ mill. Anfr. 7–7½; [var. minor]: From Paiva 1867: Variet. adest α minor, testa minore.

Diagnosis

Shell large for the genus, conical, scalariform. Whorls not rounded, vertical. Surface of the shell covered by small and relatively densely set tubercles. Second whorl and body whorl bicarinated, with upper keel weaker than the lower one. Umbilicus narrow. Last whorl descending towards the aperture. Aperture oval with continuous peristome.

Redescription of the shell

Shell medium to large for the genus, with 6½ regularly increasing whorls, the protoconch with 2 whorls. The form of the shell is conical, the convex teleoconch whorls with two sharp keels. The last whorl measures 60%, the penultimate whorl 17% of the total shell height. The lower ⅔ of the body whorl are beneath the lower peripheral keel, which is set off by a relatively deep constriction above and below the keel; outline of body whorl below the lower constriction regularly convex in frontal view. The keels of the body whorl are placed in the upper twelfth and third, respectively, of its total height. The suture between the whorls is simple and slightly sunken. The aperture, which is inclined to the vertical axis of the shell in an angle of 40° and is descending in its last 5% in an angle of 31° to the horizontal axis, has an elliptic form; its width is 42% of the total shell width and its height 26% of the total shell height. It has a slightly reflected, narrow lip, which is completely detached from the body whorl. The eccentric umbilicus, which measures 11% of the shell's total width, is circular in the last whorls and completely closed in earlier whorls. The protoconch is smooth, the teleoconch shows a number of oblique radial ribs, 19 in the penultimate quadrant of the body-whorl and is additionally covered by numerous small, ovate and rough tubercles. The number of tubercles in the standard-quadrate of the base is estimated to approximately 70. There are no traces of colouration in subfossil shells. In recent specimens, the colour pattern of the shell is the same as in H. bicarinata. Figs 118–120.

Variation of shell

The spire can be more or less elevated but always letting the shell appear remarkably conical and scalariform in shape. Subfossil and recent material does not show much variation.

Measurements

D 6.3 ± 0.4 mm (range 5.6–7.0 mm); H 6.1 ± 0.6 mm (range 5.8–6.6 mm); FW 3.7 ± 0.2 mm; PA 44.0 ± 3.2°; DU 0.6 ± 0.07 mm; NT 70 ± 16; NW 6.75 ± 0.2 (n = 7). Ratio D/H 1.0; ratio FW/H 0.6.

Distribution

Subfossil material is known, except for one location in the westernmost part of the island, exclusively from the southeastern coast of Porto Santo, i.e. the mud deposits and aeolinites along Barbinha, Zimbral da Areia and Porto dos Frades. Recent, living specimens are only known from Pico do Baixo and Ilhéu das Cenouras, collected during the 1980’s. Other recent material is kept at the NMWC 80.202, acc. 55.158 (ex coll. Melvill-Tomlin, ex coll. T. V. Wollaston) and NMWC 2004.045.00055 (ex coll. Coles) (see Seddon 2008: pl. 29 fig. C), but without exact locality data (just: Porto Santo). The distribution is shown in Fig. 121.

Figure 121. 

Distribution of Wollastonia vermetiformis. Filled circles refer to recent and open circles to fossil records.

Ecology

Living specimens were collected in the 1980s on slopes under stones covered with lichens and in a rock crack. More field research is necessary for a better understanding of the ecology and actual distribution of this species.

Comparison and comments

Wollastonia vermetiformis is superficially similar to H. echinoderma, W. falknerorum sp. n. and W. ripkeni sp. n. From the first two it differs in the development of the two keels on the body whorl, and from the second also in the much coarser shell sculpture, the more pronounced upper keel, and the narrower aperture. From the quite similar H. ripkeni sp. n. it differs in the lower last whorl, the oblique ovate aperture, the coarser granulation, and finer ribbing. From similar-sized W. subcarinulata and W. inexpectata sp. n. it can be separated by the coarser granulation and the presence of two keels. The last known recent specimens were collected during the 1980s. Unfortunately, this material was not stored in ethanol. Therefore, an anatomical and molecular investigation was not possible. Recent intensive field research (on the main island Porto Santo and its outlying islets, D. Teixeira pers. comm. 2016) failed to find any living specimen of W. vermetiformis on the Pico do Baixo. The species may possibly have gone extinct in the 1980s on the main island.

Status and conservation

Only three recent specimens of the species collected in the 1980s (KG) from two isolated localities (Porto Santo, W slope of Pico do Baixo, in a rock crack and Ilhéu das Cenouras; Fig. 121) are known. Despite intensive recent field research, the species has not been refound and is probably extinct on the main island of Porto Santo. Although recent data are missing for Ilhéu das Cenouras, we cannot exclude the existence of extant living populations on that small offshore islet. We regard the species as Critically Endangered (CR B1a, b(i, ii, iv), 2a, b(i, ii, iv)) (see also Groh 2017) because the extent of occurrence and the area of occupancy of the species is less than 1 km2 and because the species is arguably extinct at one of the two known locations (Fig. 121).

Wollastonia ripkeni De Mattia & Groh, sp. n.

Figs 122–124, 125

Type material

SMF 348929, holotype, from loc. typ., leg. W. De Mattia & J. Macor, May 2015, NMWC Z.2016.013.00008, 2 PT (paratypes), NHMW 112144/1 PT, CKG, 2 PT, CWDM, 11 PT, from loc. typ., leg. W. De Mattia & J. Macor, May 2015.

Locus typicus

Porto Santo, excavated mud walls behind the cart speedway E of the new harbour of Porto Santo, 33°03'48"N/16°18'22"W, 30 m.

Diagnosis

Shell large for the genus, solid and conical. Whorls not rounded, not vertical but somewhat slanting. Surface of the shell covered by small, and relatively densely set tubercles. Body whorl bicarinated, with upper keel weaker than the lower one. Remaining teleoconch whorls only with the upper keel visible. Umbilicus narrow. Last whorl descending toward the aperture. Aperture oval with continuous peristome.

Description of the holotype

Shell large for the genus, with 6⅔ regularly growing whorls, the protoconch with 1.85 whorls. The form of the shell is conical, the convex teleoconch whorls showing two rounded keels, the upper one less developed than the lower one. The last whorl measures 66%, the penultimate whorl 12% of the total shell height. The lower ¾ of the body whorl are beneath the lower peripheral keel, which is set off by a constriction above and below the keel; outline of body whorl below the lower constriction regularly convex in frontal view. The two keels of the body whorl are placed in the upper 111 and ¼ of its total height. The suture between the whorls is simple, not sunken. The aperture, which is inclined to the vertical axis of the shell in an angle of 50° and is descending in the last 5% of the last whorl in an angle of 35° to the horizontal axis, has an elliptic form; its width is 46%, of the total shell width, its height 31% of the total shell height. It has a slightly reflected lip, which is completely detached from the body whorl. The eccentric umbilicus, which measures 10% of the total shell width, is in the last whorls circular and completely closed in the earlier whorls. The protoconch is smooth, the teleoconch shows a number of oblique radial ribs, 13 in the penultimate quadrant of the body-whorl and is additionally covered by numerous rounded tubercles. The number of tubercles in the standard-quadrate of the base is 89. There are no traces of colouration (Figs 122–124).

Figures 122–124. 

Shells of Wollastonia ripkeni sp. n. 122 holotype, SMF 348929 123, 124 paratypes from the loc. typ. Scale bar 1 mm.

Variation of the paratypes

Although the shell size is slightly variable, its shape is remarkably stable in all specimens.

Measurements

D 8.0 ± 0.4 mm (range 7.2–8.6 mm); H 6.2 ± 0.4 mm (range 5.4–6.8 mm); FW 4.1 ± 0.2 mm; PA 42 ± 4.1°; DU 0.9 ± 0.08 mm; NT 89 ± 23; NW 6.7 ± 0.2 (n = 16). Ratio D/H 1.3; ratio FW/H 0.7.

Distribution

Known only from the locus typicus. The species was hitherto found only along a 50 m stretch of mud deposits close to the cart speedway. Additional deposits in the vicinity could not be checked for the presence of the species because of difficult accessibility of the steep slopes and associated risks of stone fall and landslides. The currently known distribution is shown in Fig. 125.

Figure 125. 

Distribution of Wollastonia ripkeni sp. n.

Etymology

Named for the Dutch malacologist Theodor (“Theo”) J. E. Ripken from Delft, The Netherlands, to honour his valuable contributions to the malacofauna of the Macaronesian Islands.

Comparison and comments

Wollastonia ripkeni sp. n. can be confused on first glance with other large-sized species such as H. echinoderma, W. falknerorum sp. n. or W. vermetiformis. From the first it is separated by the development of two distinct keels, from the second by a much finer sculpture, a narrower umbilicus and narrower aperture. From the quite similar H. vermetiformis it differs by a much more solid shell, a much higher last whorl, a larger aperture, finer granulation and coarser ribbing of the body whorl. From similar sized W. subcarinulata and W. inexpectata sp. n. it is separated by a coarser granulation and the presence of two keels.

Taxonomic remarks

Wollastonia ripkeni sp. n. is included in the genus Wollastonia because it is similar to W. oxytropis in size and surface sculpture, considerably differing from Hystricella s. str. where the tubercles are bigger and less densely set. We are well aware that, due to the lack of anatomical and molecular data, the generic placement of this subfossil species is exclusively based upon shell features, with all the taxonomic limits that this might implicate.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Wollastonia falknerorum Groh, Neiber & De Mattia, sp. n.

Figs 126–128, 129

Type material

All from Porto Santo, holotype, SMF 348925, from loc. typ., leg. W. De Mattia & J. Macor, May 24 2015; SMF 348926/2 PT, NMW.Z.2016.013.00007/2 PT, NHMW 112142/1 PT, CKG/2 PT, CWDM/22 PT, from loc. typ., leg. W. De Mattia & J. Macor, May 24 2015; NMG No. 78-14764/2 PT [as H. vermetiformis, det. H. Waldén], Prainha & Serra de Fora, 33°03'57"N/16°17'49"W, 20 m, leg. A. De Noronha, before 1978; NMG No. 86-17153/4 PT [as H. vermetiformis, det. H. Waldén], Penedo, 33°03'38"N/16°19'50"W, 10 m, leg. J. J. De Sousa, before 1986; CWDM/9 PT, Barbinha, slightly S towards the tunnel, Quaternary mixed gravel slope deposit, 33°3'56"N/16°17'49"W, 20 m, leg. W. De Mattia & J. Macor, May 24 2015; CKG/9 PT, Vale do Touro, 800 m E of Vila Baleira, 60 m NW of oil tanks, Quaternary slope deposit from the 3rd of 11 layers of tuffites with approx. 20% of stones, 33°03'49"N/16°19'21"W, 12–14 m, Jun. 18 1983, leg. K. & C. Groh; CJG/3 PT, Vale do Touro, 800 m E of Vila Baleira, 60 m NW of oiltanks, Quaternary slope deposit from the 3rd of 11 layers of tuffites with approx. 20% of stones, 33°03'50"N/16°19'21"W, 12–14 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 16 1985; CKG/3 PT + 2 juv. (no PT), Pico dos Maçarico, opposite to Porto de Abrigo, leg. K.-H. Beckmann, Jan. 17 1998; CFW 12179/1 PT, Ponta da Galé, W end of tunnel, 300 m towards port, 33°03'36"N/16°17'58"W, 25 m, leg. F. Walther, Apr. 1 2017; CFW 12178/10 PT + 4 juv. (no PT) + fragm. (no PT), Ponta da Galé, W end of tunnel, 100 m towards port, 33°03'38"N/16°17'51"W, 35 m, leg. F. Walther & E. M. Gryl, Apr. 1 2017; CFW 12177/13 PT + 6 juv. (no PT) + 1 fragm. (no PT), CKG/3 PT, Ponta da Galé, E end of tunnel, lower level [of slope deposits], coarse, red coloured gravel with large stones, 33°03'47"N/16°17'45"W, 30 m, leg. F. Walther, Apr. 1 2017; CFW 12180/34 PT + 11 juv. (no PT) + fragms (no PT), CKG/5 PT, E of Vila Baleira, end of Vale do Touro, (sub-)fossil [slope-]deposits, coarse, black gravel, 33°03'48"N/16°19'15"W, 20 m, leg. F. Walther, Apr. 5 2017; CFW 12181/21 PT + 4 juv. (no PT) + fragms (no PT), E of Vila Baleira, S-slope of the hill above Vale do Touro, W of the oil tanks, [(sub-)fossil slope-deposits of] red gravel, 33°03'47"N/16°19'26"W, 25 m, leg. F. Walther, Apr. 5 2017; ANSP H 11854/9 PT [partim, together with 7 H. subcarinulata and 2 Discula cheiranticola], Barbinha, 33°04'04"N/16°17'49"W, 8 m, leg. J. & C. Hemmen & K. & C. Groh, 1983.

Locus typicus

Porto Santo, Pico do Baixo, E entrance of the tunnel, Quaternary mud deposit, 33°3'44"N/16°17'45"W, 20 m.

Diagnosis

Wollastonia species with two keels on the body whorl, the upper keel only very weakly developed; suture overlapping; granulation very fine; ribbing of the body whorl rather coarse.

Figures 126–128. 

Shells of Wollastonia falknerorum sp. n. 126 holotype, SMF 348925127 127, 128 paratypes from the loc. typ. Scale bar 1 mm.

Description of the holotype

Shell large for the genus, with 6.5 regularly increasing whorls, the protoconch with 2.1 whorls. The form of the shell is conical, the convex teleoconch whorls show an upper, rounded angulation and a lower distinctly developed keel. The last whorl measures 60%, the penultimate whorl 10%, of the total shell height. The lower ¾ of the body whorl are beneath the keel, which is set off by a constriction above and below; shell below the lower constriction regularly convex in frontal view. The angulation of the body whorl is placed in the upper seventh of its total height and the keel in the upper fourth of its total height. The suture between the whorls is simple, but slightly overlapping the previous whorl. The aperture, which is inclined to the vertical axis of the shell in an angle of 54° and is descending in the last 5% of the last whorl in an angle of 42° to the horizontal axis, has an elliptic form, which is slightly narrowed towards the columella. Its width is 45%, of the total shell width and its height 31% of the total shell height. It has a slightly reflected lip, which is completely detached from the body whorl. The eccentric umbilicus, which measures 14% of the shell's total width, is in the last whorls circular and completely closed in earlier whorls. The protoconch is smooth, the teleoconch shows a number of oblique radial ribs, 9 in the penultimate quadrant of the body whorl and is additionally covered by numerous small, rounded tubercles. The number of tubercles in the standard-quadrate of the base is 135. There are traces of colouration in form of large blotches along the last two whorls (see Fig. 126).

Variation of the paratypes

The shell shape is quite stable in all examined specimens (Figs 127–128).

Measurements

D 8.4 ± 0.1 mm (range 8.2–8.5 mm); H 7.0 ± 0.3 mm (range 6.8–7.4 mm); FW 4.3 ± 0.2 mm; PA 42 ± 5.3°; DU 0.9 ± 0.09 mm; NT 68 ± 18; NW 6.5 ± 0.2 (n = 20). Ratio D/H 1.2; ratio FW/H 0.6.

Distribution

Wollastonia falknerorum sp. n. is found in the Quaternary mud and slope deposits along the southeastern coast of Porto Santo. Its range extends from the hills east of Vila Baleira to Barbinha, S of Porto dos Frades. The distribution is shown in Fig. 129.

Figure 129. 

Distribution of Wollastonia falknerorum sp. n.

Etymology

Named for the German malacologists Margrit & Gerhard Falkner, Hörlkofen, to honour their highly valuable contributions to European malacology.

Comparison and comments

Wollastonia falknerorum sp. n. can be confused on first glance with other comparatively large-sized geomitrid species like, H. echinoderma, W. ripkeni sp. n. and W. vermetiformis. From the first it is distinguishable by the presence of two distinct keels and from all three by a much finer sculpture. From the most similar W. vermetiformis and W. ripkeni sp. n. it is differentiated by the weakly developed upper keel, an overlapping suture, a much finer granulation and coarser ribbing of the body whorl. From similar-sized W. subcarinulata and W. inexpectata sp. n. it is separated by the two keels and the differently developed suture.

Taxonomic remarks

Wollastonia falknerorum sp. n., as with other subfossil Wollastonia species, is included in this genus because it is similar to W. oxytropis in shell shape, size and surface sculpture, which differ considerably from Hystricella species. We are well-aware that, due to the lack of anatomical and molecular data, the generic position of this subfossil species is exclusively based upon shell features, with all the taxonomic limits that this might implicate.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Wollastonia leacockiana (Wollaston, 1878), comb. n.

Figs 130–132, 133–141, 142

List of synonyms

1878 Helix (Hystricella) leacockiana Wollaston: 165–167.

1894 Geomitra leacockiana – Pilsbry in Pilsbry 1893–1895: 34.

1931 Geomitra (Actinella) bicarinata var. leacockiana – Nobre: 87.

1950 Discula (Hystricella) leacockiana – Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) leacockiana – Waldén: 20: 267.

2002 Geomitra leacockiana – Bank et al.: 124.

2008 Hystricella leacockiana – Seddon: 79–80, pl. 29 fig. A, map 179.

2011 Hystricella leacockiana – Seddon: e.T6720A12799605.

Type material

NHM 1875.12.31.137-d, lectotype (herewith designated), from loc. typ., ex coll. T. V. Wollaston; NHM 1875.12.31.137-a to -c and -e, 4 paralectotypes, from loc. typ., ex coll. T. V. Wollaston.

Further material examined

All from Porto Santo, CWDM/14, CMN/3, Pico de Ana Ferreira, northern slopes near the ‘lava columns’, under stones scattered in open grassy fields, 33°02'57"N/16°22'04"W, 125 m, leg. W. De Mattia & J. Macor, May 2014; CKG/32, CMN/9, Pico de Ana Ferreira, top of the hill, under stones scattered in open grassy fields, 33°02'39"N/16°22'11"W, 230 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 6 1983; CKG/20, CMN/10, E slope of Pico de Ana Ferreira, 33°02'37"N/16°22'05"W, 100–200 m, leg. K. & C. Groh, Oct. 26 1980; CKG/1, Ilhéu de Ferro, east side of the island plateau, under stones scattered in open grassy fields, 33°02'19"N/16°24'26"W, 75 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 2 1983; CFW 11151/<10, N slope of Pico de Ana Ferreira, near the basalt columns, 33°02'57"N/16°22'03"W, 125 m a.s.l., leg. F. Walther & E. M. Gryl, Mar. 30 2017; CFW 11152/<10 spms, Pico de Ana Ferreira, summit, 33°02'38"N/16°22'13"W, 230 m, leg. F. Walther, Apr. 4 2017; ANSP H 11838/c. 40, NW slope of the Pico de Ana Ferreira, 33°02'48"N/16°22'11"W, 190 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 6 1983; ANSP H 11770/ c. 30 [sub H. bicarinata], E slope of Pico de Ana Ferreira, 33°02'37"N/16°22'05"W, 100–200 m, leg. J. & C. Hemmen, Jan. 5 1981.

Locus typicus

Portum Sanctum; in monte ‘Pico d’Anna Ferreira’ dicto sat copiose reperta. Necnon in statu semifossili (cum exemplaribus recentibus vix omnino congruens) parcissime occurrit.

Original description

From Wollaston, 1878: T. trochiformis, subtus planata perforata, undique granulis obtusis densissime obsita, pallide brunneo-subflavescens sed fasciis (præsertim subtus) nebulisque irregiularibus (præsertim supra) rufo-brunneis hinc inde suffuse marmorata; spira sat elevata; anfractibus convexis, bicarinatis, ultimi (subtectiformis) carina exteriore acutissima valde exstanti, interior obtusa rotundata recedente rarius obsoleta; umbilico punctiformi; apertura subovali-rotundata, labris continuis conjunctis, peristomate simplici expanso subrecurvo tenui relevato. – Long. axis 1⅔ lin.; diam. 2½.

Redescription of the shell

The shell is dextral, hairless and it is usually conical and scalariform. The protoconch is from whitish to brown with 1.6 to 1.9 whorls. It is almost smooth along the first half whorl and shows fine radial striae and extremely small, scattered tubercles along its remaining portion. The teleoconch has from 3.9 to 4.4 rapidly increasing whorls. It is variable in colour, from very light brown to brown. The background colour is mottled with brownish to dark-reddish areas, irregularly arranged along the whorls. No band pattern is visible along the upper whorls. On the lower part of the last whorl two more or less indistinct, dark bands are visible. The peripheral band is usually the thinnest and often very indistinct. The spire is usually pyramidal and slightly scalariform. Along the last and partially along the penultimate whorl one evident keel is present. This keel extends along the lower part of the whorls and is usually lighter in colour, sometimes whitish. The external upper surface has very fine but clearly visible, irregularly spaced, growth lines. Irregularly disposed tubercles are present all over the teleoconch. The dimensions of the tubercles tend to slightly increase from the first towards the last whorl, but keeping approximately the same density. The tubercles are somewhat denser along the keel, letting the keel appear like a rough chord. The tubercles usually also concentrate somewhat along the growth lines. On the lower part, the tubercles are much denser along the periphery and gradually become scarcer towards the umbilicus. The last whorl is relatively large and descending near the aperture. The umbilicus is open but very narrow, concentric and measures approximately 10% of the maximum shell diameter. The aperture is elliptical with a quite strong thickening along the inner side of the last whorl. The peristome is continuous, slightly reflected with the columellar margin being somewhat thicker (see Figs 130–132).

Figures 130–132. 

Shells of Wollastonia leacockiana. 130 lectotype of Helix leacockiana Wollaston, 1878, NMH 1875.12.31.137d, ex coll. Wollaston 131 Pico de Ana Ferreira 132 Ilheu de Ferro. Scale bar 1 mm.

Measurements

D 5.3 ± 0.2 mm (range 5.0–5.6 mm); H 4.0 ± 0.3 mm (range 3.7–4.8 mm); FW 2.6 ± 0.2 mm (range 2.4–2.6); PA 58.8 ± 2.1° (range 55.0–60.0°); DU 0.5 ± 0.1 mm (range 0.4–0.6); NT 49 ± 5 (range 44–56); NW 5.4 ± 0.1 (range 5.3–5.5) (n = 40). Ratio D/H 1.3; ratio FW/H 0.6.

Body

The head and neck are usually light grey, as is the posterior upper section of the foot. The foot is white and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral areas are equipped with bands of muscles roughly arranged in a chevron pattern. The mantle border is light grey, with five more or less developed lobes. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible. The jaw is odonthognatous and its shape is arched. There are 8 to 10 smooth transverse ridges. The right ommatophoral retractor is independent from both penis and vagina.

Genital anatomy

The albumen gland is long and it is connected to an approximately equally long sperm-oviduct. The thin vas deferens is approximately as long as the sperm-oviduct. The free oviduct is shorter than the vagina. The duct of the bursa copulatrix is usually thin, approximately as long as the penis and uniform in diameter. The bursa copulatrix is roundish. The transition area between the duct and the bursa itself is very sharply delimited, with the duct abruptly widening and turning into the bursa. The spermatophore is unknown. One tuft of a digitiform glands arises from the proximal part of the vagina. There are two or three glands that are equally long and never branched. A short and thin vaginal appendix arises from the vagina’s wall, just distal of the glandular tuft. The inner surface of the vagina is smooth. The atrium is usually long (¾ of the vagina) and relatively thin. Its internal walls are also smooth. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus and its internal walls are completely smooth. The internal walls of the epiphallus are completely smooth as well. The retractor muscle is moderately long, strong and is of variable length. The penis lacks any muscular or glandular sheath. It is thick-walled and approximately three to four times longer than the flagellum. It is usually cylindrical, sometimes slightly swollen and partially folded up. The inner walls of the penis are smooth. The penial papilla is small and bulky. It has smooth external walls with the opening emerging apically but somewhat curving inwards. The channel of the penial papilla is thin and narrow and its cross section is ‘half-moon’-shaped. The inner lumen of the penial papilla is filled with a spongy and sturdy tissue, which directly connects with the walls of the epiphallus. As all the previous species, the longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward (see Figs 133–141).

Figures 133–141. 

Genitalia and anatomy of Wollastonia leacockiana. Pico de Ana Ferreira, N slopes: 133 section of penial papilla 134 section of vagina 135 whole genitalia excluding gonads 136 tip of the penial papilla 137 longitudinal section of penial papilla 138 ornamentation of the inner walls of the distal penis, the distal vagina and the genital atrium 139 whole genitalia excluding gonads 140 jaw 141 mantle border. Scale bars 1 mm.

Ecology

Wollastonia leacockiana is commonly found under volcanic rocks and boulders scattered on grassland in open fields that are more or less sloping. The specimens aestivate on the lower surfaces of the rocks, frequently forming clusters of individuals attached one to another.

Distribution

Wollastonia leacockiana is restricted to Pico de Ana Ferreira and Cabeco da Ponta at the western end of Porto Santo, with records also from Ilhéu de Ferro (CGK), although surveys are required to confirm if the species is still extant on that islet. Seddon (2008: 79, 182) reported the species from a spot at the eastern end of Porto Santo (Ponta do Passo area?). Despite intensive recent field research (WDM 2012, 2014, 2015) the species has not been confirmed in this area. Seddon’s (2008) record could represent a misidentification of a different species (cf. W. klausgrohi sp. n.). The currently known distribution is shown in Fig. 142.

Figure 142. 

Distribution of Wollastonia leacockiana.

Taxonomic remarks

As reported by Seddon (2008: 79), Wollaston (1878: 161) separated W. leacockiana from H. bicarinata on the basis of its shell sculpture. This study confirmed Wollaston’s (1878) opinion, as do our molecular analyses and the investigation of the anatomy of the species.

Status and conservation

The species is currently not significantly impacted by the construction of touristic/residential facilities in its distributional range; only in the Cabeco da Ponta area some new buildings were recently constructed. Recent surveys (WDM, 2012, 2014, 2015) showed that the species is currently widely distributed and common within its range. According to Seddon (2011c) the species is Vulnerable (VU D2), an assessment we regard as appropriate here because of the small range of the species and the potential threat of future construction works in the area. Further research is required to confirm the distribution of the species.

Wollastonia beckmanni De Mattia & Groh, sp. n.

Figs 143–145, 146

Type material

All from Porto Santo, SMF 348927, holotype, from loc. typ., leg. K. & C. Groh, June 6 1983; SMF 348928/5 PT, MMF 24956/1 PT, MMF 46281/1 PT, MMF 46282/1 PT, NHMW 112143/1 PT, CKG/62 PT, NMWZ 2016.013.00009/5 PT, CJG/5 PT, from loc. typ., leg. K. & C. Groh, June 6 1983; CWDM/12 PT, E of Vila Baleira, S slope of the hill above Vale do Touro, 50 m W of the oil tanks, excavated Quaternary mixed gravel, 33°03'47"N/16°19'26"W, 24 m, leg. W. De Mattia & J. Macor, May 24 2015; CFW 12176/5 PT, E of Vila Baleira, S slope of the hill above Vale do Touro, W of the oil tanks, [(sub-)fossil slope-deposits of] red gravel, 33°37'52"N/16°19'26"W, 25 m, leg. F. Walther, Apr. 5 2017; ANSP H 11843/2 PT [sub H. leacockiana], Vale do Touro, 33°03'46"N/16°19'29"W, 15 m a, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 16 1985.

Locus typicus

Porto Santo, south coast, ditch near the harbour built in 1985 at Vila Baleira, lens of quaternary calcareous aeolinite within a marine sandy beach terrace (nowadays beyond the quay of the harbour), 33°03'50"N/16°18'56"W, 0–1.5 m.

Diagnosis

Small Wollastonia species with a very depressed body whorl that is finely granulated; umbilicus very wide in relation to maximum diameter, rather eccentric.

Description of the shell of the holotype

Shell small for the genus, with 5.15 rapidly increasing whorls, the protoconch measures 1.5 whorls. The form of the shell is flat conical, the convex teleoconch whorls show a strongly keeled periphery. The last whorl measures 65%, the penultimate whorl 14% of the total shell height. The lower half of the body whorl is slightly concave beneath the keel in frontal view near the periphery and otherwise regularly convex. The suture between the whorls is simple and slightly impressed. The aperture, which is inclined to the vertical axis of the shell in an angle of 58° and descending in the last 5% of the last whorl in an angle of 43° to the horizontal axis, has an elongate-ovate form, its width measures 42% of the total shell width, its height 27% of the total shell height. It has a distinctly reflected lip, which is completely detached from the body whorl. The very eccentric umbilicus, which measures 17% of the total shell width, is in the upper whorls narrowly perspective. The protoconch is smooth, the teleoconch shows a low number of oblique radial ribs, nine in the penultimate quadrant of the body whorl and is additionally covered by many fine tubercles. The number of tubercles in the standard quadrate of the base is 102; the tubercles become coarser towards the centre of the base and finer towards the periphery. There are no traces of colouration (see Fig. 143).

Figures 143–145. 

Shells of Wollastonia beckmanni sp. n. 143 holotype, SMF 348927 144 paratype from the loc. typ. 145 Vale do Touro. Scale bar 1 mm.

Variation in paratypes

The size varies slightly, and the density of the tubercles in the standard quadrate of the base may vary by ± 10%. Exceptionally, the umbilicus may be narrower and the angles of the aperture to the vertical axis and the descending of the last part of the body whorl to the vertical axis also slightly vary (see Measurements section below). Nevertheless, the overall shape and sculpture of all paratypes is very close to that of the holotype. In a few shells traces of a brownish colouration are perceptible, however there are no traces of a banding pattern (see Figs 144–145).

Measurements

D 5.3 ± 0.2 mm (range 5.0–5.6 mm); H 3.3 ± 0.2 mm (range 3.2–3.5 mm); FW 2.2 ± 0.1 mm (range 2.1–2.3 mm); PA 72.0 ± 3.0° (range 66.0–76.0°); DU 0.4 ± 0.05 mm (range 0.3–0.4 mm); NW 6.2 ± 0.2 (range 6.0–6.4) (n = 20). Ratio D/H 1.6; ratio FW/H 0.7.

Distribution

Wollastonia beckmanni sp. n. is known only from the southeastern coast of Porto Santo, from the hill immediately east of Vila Baleira (mud deposits at Vale do Touro) to the aeolinite deposits behind the new harbour. See map in Fig. 146.

Figure 146. 

Distribution of Wollastonia beckmanni sp. n.

Etymology

Named after the late German entrepreneur and self-taught malacologist Dr. Karl-Heinz Beckmann (1948–2007) to honour his valuable contributions to the malacofauna of different islands and archipelagos in the Mediterranean and the Atlantic.

Comparison and comments

Because of its small size the new species can only be confused with small H. aucta Wollaston, 1878, which have, however, a higher and more distinctly stepped spire, have two well-developed keels and much coarser and more sparsely set tubercles on the shell surface. Hystricella microcarinata sp. n. has a much higher, rounded conical form, two keels on the body whorl, coarser and less densely set tubercles, a much narrower umbilicus, and a different shape and differently positioned angles of the aperture.

Taxonomic remarks

As with other subfossil Wollastonia species, W. beckmanni sp. n. is included in this genus because it considerably differs from Hystricella and is similar to W. oxytropis in surface sculpture and overall shell shape.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Wollastonia jessicae jessicae De Mattia, Neiber & Groh, sp. n.

Figs 147–149

Type material

NMWC Z.2016.013.00001, holotype, from loc. typ., leg. W. De Mattia & J. Macor, May 25 2015, NMWC Z.2016.013.00002/4 PT, SMF 348934/4 PT, NHMW 112140/3 PT, CKG/3 PT, CMN/7 PT, CWDM/23 PT, from loc. typ., leg. W. De Mattia & J. Macor, May 24 2015; FW 11154/10 PT, CMN/10 PT, ZMH 131207, 10 PT, hill E of Ribeira Santo Antonio and W of Vale do Touro, upper edge of the S slope, 33°03'47"N/16°19'41"W, 40 m, leg. F. Walther, Apr. 5 2017; CKG/5 PT, CJG/2 PT, Vale do Touro, under stones, 33°03'51"N/16°19'26"W, 45 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 16 1985. Fossil: CKG/2 PT, Vale do Touro, Quaternary slope deposits, 33°03'47"N/16°19'26"W, 25 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 16 1985. GNM 72-13.386/1 PT, Portela, 500 m SW, in the road cutting, Quaternary muds, 33°03'54"N/16°19'12"W, 95 m, leg. H. W. Waldén, Feb. 13 1972; ANSP H 11920/7 PT [with 8 spms of H. aucta], Vale do Touro, Quaternary slope deposits, 33°03'47"N/16°19'26"W, 25 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 16 1985; ANSP H 11773/2 PT [with 3 Caseolus compactus], Vale do Touro, under stones, 33°03'51"N/16°19'26"W, 45 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 16 1985.

Locus typicus

Upper edge of the S slope of hill E of Ribeira Santo Antonio and W of Vale do Touro, under stones in grassland, 33°03'47"N/16°19'41"W, 40 m.

Diagnosis

Small Wollastonia species, with a conical shell and two keels on the body whorl, the lower more distinct than the upper; granulation relatively fine and scattered; internal walls of penis with one to three well-developed, irregular pleats.

Etymology

Named after the wife of the first author, Mrs. Jessica Macor from Trieste, Italy, as a token of gratitude for her assistance and companionship during the collecting activities.

Description of shell

The shell is dextral and hairless. Its shape is scalariform, with deep sutures and rather flattened whorls. The protoconch is from yellowish to dark brown with 1.5 to 2.5 whorls. It is almost smooth along the first whorl and shows fine radial striae in its remaining whorls. The teleoconch has from 3.3 to 3.8 rapidly increasing whorls. It is usually dark brown with brick red and/or dark violet shades in colour, but also yellowish specimens with light reddish shades are found. The darker areas of the shell are mottled with more or less light brown to whitish areas, usually placed longitudinally and slightly slanting. The body whorl has two well-developed keels. The lower one is stronger and more distinct than the upper one. Both keels are usually whitish and contrasting from the rest of the body whorl. No banding pattern is visible along the upper whorls. On the lower part of the last whorl one principal, but rather narrow, dark (reddish to dark brown) band is usually present. A second light and indistinct band is sometimes present just below the keel. The area around the umbilicus is usually the lightest in colour. The external surface has strong, clearly visible, irregularly spaced, growth lines. Tubercles are present all over the teleoconch. They are usually large and rather widely scattered, whitish in colour and arranged somewhat obliquely, following the course of the growth lines. The larger tubercles are somewhat denser along the keel(s) of the last whorls, letting the keel(s) appear like a rough chord. The last whorl is usually large, with a contribution of 60% of the total shell height and descending near the aperture. The umbilicus is open but very narrow, either concentric or eccentric, and it measures approximately 10% of the maximum shell diameter. The aperture is elliptical with a faint thickening along the columellar portion of the stoma. Sometimes this thickening can also extend as far the parietal side of the aperture. The peristome is continuous and reflected (see Figs 147–149).

Figures 147–149. 

Shells of Wollastonia jessicae jessicae sp. n. 147 holotype, NMWC Z.2016.013.00001 148 paratype from the loc. typ. 149 subfossil specimen from Vale do Touro. Scale bars 1 mm.

Measurements

D 4.8 ± 0.3 mm (range 4.4–5.2 mm); H 3.3 ± 0.3 mm (range 3.0–3.9 mm); FW 2.3 ± 0.1 mm (range 2.2–2.4 mm); PA 58.2 ± 7.4° (range 50.0–68.0°); DU 0.7 ± 0.05 mm (range 0.6–0.8 mm); NT 23 ± 12 (range 9–37); NW 5.6 ± 0.4 (range 5.0–5.9) (n = 40). Ratio D/H 1.5; ratio FW/H 0.7.

Body

The head and the neck are usually grey. The sides and the posterior upper section of the foot are whitish. The pigmented ommatophoral retractor muscles are visible through the skin of the back of the cephalic area. The foot is white and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral areas are equipped with bands of muscles that are roughly arranged in a chevron pattern. The mantle border is grey to dark grey, with five more or less developed lobes. The ratio of the lateral to the dorsal lobes varies from specimen to specimen, also in the same population. In some specimens, one of these lobes (either lateral or dorsal) may be totally missing. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible. The jaw is odonthognatous and is very variable in shape, ranging from almost straight to markedly arched. There are many smooth transverse ridges, ranging from 18 to 22 in number. The right ommatophoral retractor is independent from both penis and vagina.

Genital anatomy

The general arrangement of the genitalia is semi-diaulic monotrematic. A convoluted to almost straight hermaphrodite duct arises from a multi-lobated gonad. The albumen gland is long and thin and is connected to an approximately twice as long sperm-oviduct that consists of a prostatic and a uterine portion. The prostatic part extends into a thin vas deferens, which is approximately as long as the sperm-oviduct and terminates in the penial complex. The distal portion of the uterine part extends into the free oviduct, turning into a vagina at the level of the duct of the bursa copulatrix. The free oviduct can be as long as, or slightly shorter than the vagina. The duct of the bursa copulatrix is usually thin, approximately as long as the penis and uniform in diameter. It ends into a variable, oval to roundish, bursa copulatrix. The transition area between the duct and the bursa itself is usually sharply delimited, with the duct abruptly widening and turning into the bursa. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually two glands that are approximately equally long and very rarely branched. A short and thin vaginal appendix arises from the vagina’s wall, just distal of the glandular tuft. Very smooth, rather wide and little elevated, irregularly spaced pleats run longitudinally along the inner surface of the vagina, reaching into the genital atrium as far as the genital orifice. The atrium is usually long and thin. Its internal walls have large and soft pleats running longitudinally as far the genital orifice. The penial complex consists of a flagellum, an epiphallus (which extends from the insertion of the vas deferens to the penial retractor muscle) and a penis, which inserts into the atrium. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus. Its internal walls are completely smooth. The epiphallus is usually short and its internal walls present 2 to 4 longitudinal, smooth pleats that are only slightly elevated. The retractor muscle is not very large, but strong, usually as long as the flagellum + epiphallus together. The penis lacks any muscular or glandular sheath. It is thick-walled and approximately three times longer than the flagellum. It is usually slightly swollen in its distal part near the genital atrium. The inner walls of the penis usually have one to three irregular, spaced pleats, which run longitudinally and reach the genital atrium. These pleats can be connected by small “bridge-like” pleats. In some specimens, the section where the penial papilla is located is detectable from the outside by virtue of a fine circular swelling corresponding to the origin of the papilla itself. The penial papilla is usually very variable in dimensions (measuring from 10% to 50% of the total penial length) and conical in shape. It has smooth external walls, with the opening emerging apically. The channel of the penial papilla is thin and narrow. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue, which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward (see Figs 150–157).

Figures 150–157. 

Genitalia and anatomy of Wollastonia jessicae jessicae sp. n. S slope of hill E of Ribeira Santo Antonio and W of Vale do Touro: 150 whole genitalia excluding gonads 151 section of proximal penis at the intersection with vas deferens 152 whole genitalia excluding gonads 153 ornamentation of the inner walls of the distal penis, the distal vagina and the genital atrium 154 jaw 155 mantle border 156 whole genitalia excluding part of OSD, AG and gonads 157 ornamentation of the inner walls of the distal penis, the distal vagina and the genital atrium. Scale bars 1 mm.

Distribution

Wollastonia jessicae jessicae sp. n. is found only along the southern slope of a hill east of Ribeira Santo Antonio and west of Vale do Touro, just east of the town of Vila Baleira, along the road leading to the new harbour. The distribution is shown in Fig. 158.

Figure 158. 

Distribution of Wollastonia jessicae jessicae sp. n. Filled circles refer to recent and open circles to fossil records.

Ecology

Wollastonia jessicae jessicae sp. n. is commonly found under volcanic rocks scattered on grassland in open fields that are more or less sloping. The specimens aestivate on the lower surfaces of the rocks, frequently forming clusters of individuals attached one to another.

Comparison and comments

At first glance W. jessicae jessicae sp. n. can be confused with H. bicarinata because of the overall similarity of their shell’s shape (i.e. granulated surface with the last whorl with two keels). This is probably the reason why the new species has been overlooked until now. Nevertheless, a closer look reveals differences such as the much coarser granulation on the surface of H. bicarinata.

W. jessicae jessicae sp. n. (as for W. jessicae monticola sp. n. described in the following section) always shows a finer granulation, having smaller and more scattered tubercles. With regard to genital anatomy, W. jessicae jessicae sp. n. has internal walls of the penis with one to three irregular and well-spaced strong pleats, which run longitudinally and reach the genital atrium, whereas H. bicarinata has at least some large and smooth folds. Our phylogenetic analysis clearly show that the two species are not closely related, i.e. they were placed in two well-separated clades. This further corroborates, aside from morphology, its status as a distinct species.

Status and conservation

The subspecies has a very limited distribution area of less than 1 km2 (Fig. 158) close to a village and population size is probably rather low. Habitat quality is inferred to be declining and potential and ongoing threats to the subspecies include, in our opinion, urbanization, tourism, goat grazing and quarrying. Therefore, the species is considered here to be Critically Endangered (CR B1a, b(iii), 2a, b(iii)).

Wollastonia jessicae monticola De Mattia, Neiber & Groh, ssp. n.

Figs 159–161, 162–166, 167

Type material

NMWC Z.2016.013.00010, holotype, from loc. typ., leg. W. De Mattia & J. Macor, May 21 2015, NMWC Z.2016.013.00011/4 PT, SMF 348931/4 PT, NHMW 1121341/3 PT, CKG/3 PT, CMN/3 PT, CWDM/6 PT, from loc. typ., leg. W. De Mattia & J. Macor, May 21 2015; FW 11155/5 PT, CMN/5 PT, ZMH 131208/4 PT, 200 m SW of the Zimbreiro near the road turn serpentine, 33°04'16"N/16°18'53"W, 100 m, leg. F. Walther, Mar. 31 2017; FW 11157/>10 PT, ridge between Zimbreiro and the quarry, 33°04'13"N/16°18'49"W, 110 m, leg. F. Walther, Apr. 3 2017.

Locus typicus

Porto Santo, Zimbreiro, 200 m SW of the village, near the road turn serpentine, 33°04'16"N/16°18'53"W, 85 m.

Diagnosis

Subspecies of Wollastonia jessicae with two keels on the body whorl, the lower distinct, the upper one very weakly developed to lacking; granulation relatively fine and scattered; internal walls of penis smooth, without pleats or prominent folds.

Etymology

Named for the restriction of its habitat to the mountainous region (Lat. mons, montis = mountain(s) and -cola = inhabitor) of the island of Porto Santo.

Shell. Similar to the nominate subspecies, except for the ornamentation of the body whorl. In W. jessicae monticola ssp. n. the upper keel is missing and the lower keel is somewhat less strongly developed and less evident compared to W. jessicae jessicae sp. n. (see Figs 159–161).

Figures 159–161. 

Shells of Wollastonia jessicae monticola ssp. n 159 holotype, NMWC Z.2016.013.00010 160, 161 paratypes from the loc. typ. Scale bar 1 mm.

Measurements

D 4.6 ± 0.2 mm (range 4.2–4.9 mm); H 3.1 ± 0.1 mm (range 2.8–3.6 mm); FW 2.0 ± 0.1 mm (range 1.9–2.3 mm); PA 58,6 ± 6.1° (range 51.3–65.7°); DU 0.7 ± 0.04 mm (range 0.6–0.8 mm); NT 25 ± 14 (range 8–39); NW 5.5 ± 0.3 (range 4.9–5.9) (n = 30). Ratio D/H 1.5; ratio FW/H 0.6.

Body

The overall body colouration (i.e. head, neck and sides) of W. jessicae monticola ssp. n. tends to be somewhat darker than in the nominate subspecies.

Genital anatomy

The distal genitalia of W. jessicae monticola ssp. n. are similar to those of the nominate subspecies, except for the inner ornamentation of the genital atrium and penis that is, contrary to W. jessicae jessicae sp. n., completely smooth, without any pleats or folds. Minor differences can also be found in the length of the vaginal digitiform glands that are, on average, longer in W. jessicae monticola ssp. n. (see Figs 162–166).

Figures 162–166. 

Genitalia and anatomy of Wollastonia jessicae monticola ssp. n. Zimbreiro, 200 m SW of the village: 162, 163 whole genitalia excluding gonads 164 ornamentation of the inner walls of the distal penis, the distal vagina and the genital atrium 165 penial papilla and inner ornamentation of proximal penis 166 mantle border. Scale bars 1 mm.

Ecology

W. jessicae monticola ssp. n. lives in a sloping hollow, in a relative humid spot along a temporary creek. The new taxon has been found exclusively under small volcanic stones in shady places under small shrubs. Its ecology differs somewhat from all the other Hystricella and Wollastonia species on Porto Santo, which are usually found under stones in open, dry grassland areas or on exposed rocky cliffs. W. jessicae monticola sp. n. has been found syntopically with Callina bulverii.

Distribution

W. jessicae monticola ssp. n. is only known from the area in the vicinity of the locus typicus. Despite extensive field research in the area, the subspecies seems to occupy an area not larger than 100 m2 (see Fig. 167 for the distribution map).

Figure 167. 

Distribution of Wollastonia jessicae monticola ssp. n.

Comparison and comments

The new taxon differs from the nominate subspecies H. jessicae jessicae sp. n. by the almost complete lack of the upper keel on the body whorl and by the smooth internal genital atrium and penis. There is also a significant distributional gap between the two conspecific taxa and the habitats and altitudinal ranges also differ. In the phylogenetic analyses, W. jessicae monticola ssp. n. represents the sister group of W. jessicae jessicae inside the W. jessicae s. lat. clade, but divergence is rather low which speaks for a relatively recent separation and may be taken as justification for the subspecific status of the two taxa.

Status and conservation

The subspecies has a very limited distribution area of less than 1 km2 (Fig. 167) close to a village and population size is probably rather low. Habitat quality is inferred to be declining and potential and ongoing threats to the species include, in our opinion, urbanization, tourism, goat grazing and quarrying. Therefore, the subspecies is considered here to be Critically Endangered (CR B1a, b(iii), 2a, b(iii)).

Wollastonia klausgrohi De Mattia & Neiber, sp. n.

Figs 168–170, 171–181, 182

Type material

NMWC Z.2016.013.00003, holotype, from loc. typ., leg. W. De Mattia & J. Macor, May 27 2015; NMWC Z.2016.013.00004/4 PT, SMF 348932/4 PT, NHMW 112139/3 PT, CKG/3 PT, CWDM/8 PT, CMN/4 PT, from loc. typ., leg. W. De Mattia & J. Macor, May 24 2015; FW 11156/25 PT, CMN/10PT, ZMH 131209/10 PT, Casa Velhas, next to the W edge of the old quarry, 33°04'06"N/16°18'51"W, 125 m, leg. F. Walther, Apr. 3 2017; CGK/3 PT, Portela, 33°03'58"N/16°19'03"W, 146 m, leg. K. & C. Groh, Oct. 25 1980; ANSP H 11784/8 PT, approx. 200 m SE of Casas Velhas, 33°04'04"N/16°18'47"W, 120 m, leg. J. & C. Hemmen & K. & C. Groh, Jul. 8 1983; ANSP H 11772/14 PT, approx. 50 m above Capela da Graça, 33°04'28"N 16°19'26"W, 165 m, leg. J. & C. Hemmen, Jan. 4 1981.

Locus typicus

Casa Velhas, next to the W edge of the old quarry, under stones, 33°04'06"N/16°18'52"W, 124 m.

Diagnosis

Small Wollastonia species, with two well-developed keels on the body whorl, the upper slightly less distinct than the lower; shell relatively dark coloured (in comparison with W. jessicae); internal walls of vagina, penis and genital atrium smooth, without folds.

Description of shell

The shell is dextral and hairless. Its shape is conical and markedly scalariform, with deep sutures. The protoconch is completely dark brown with 1.5 to 2.5 whorls. It has fine radial striae starting from the first protoconch whorl; very few and scattered small tubercles may also be present on its last portion. The teleoconch has from 3.4 to 3.9 rapidly increasing whorls. It is dark brown, sometimes with dark violet shades. The dark areas of the shells are mottled with more or less light brown to whitish areas, usually arranged longitudinally and slightly slanting. In most specimens, the lighter areas tend to be more evident along the keel of the body whorl. No band pattern is visible along the upper whorls. On the lower part of the last whorl two dark bands are present. The inner band is usually thinner but more evident, whereas the outer band is usually weaker but broader. The area around the umbilicus is the lightest in colour. Some specimens clearly have two evident keels starting already from the second whorl of the teleoconch, with the upper keel being more distinct than the lower one. In other specimens only the upper keel is visible. The body whorl is equipped with two keels, with the lower, principal keel somewhat protruding and the upper much less distinct. The whorls are flat and form a ‘shoulder’ giving them an angular contour. The external surface has strong, clearly visible, irregularly spaced, growth lines. Irregularly disposed tubercles are present all over the teleoconch. The tubercles are usually small and scattered, usually whitish in colour. The tubercles are somewhat denser along the keels of the penultimate and last whorl, letting the keel(s) appear like a rough, whitish chord. The last whorl is rather large, contributing 60% to the total shell height and descending near the aperture. The umbilicus is open but very narrow, eccentric, and measures approximately 10% of the maximum shell diameter. The aperture is elliptical, with a faint thickening along its columellar portion. This thickening also extends as far as the parietal side of the aperture. The peristome is continuous and distinctly reflected (see Figs 168–170).

Figures 168–170. 

Shells of Wollastonia klausgrohi sp. n. 168 holotype, NMWC Z.2016.013.00003 169, 170 paratypes from the loc. typ. Scale bar 1 mm.

Measurements

D 5.3 ± 0.2 mm (range 5.1–5.5 mm); H 4.0 ± 0.2 mm (range 3.8–4.2 mm); FW 2.5 ± 0.1 mm (range 2.4–2.6 mm); PA 58.0 ± 3.4° (range 52.8–60.4°); DU 0.5 ± 0.07 mm (range 0.4–0.6 mm); NT 57 ± 17 (range 46–77); NW 5.6 ± 0.1 (range 5.5–5.7) (n = 25). Ratio D/H 1.3; ratio FW/H 0.6.

Body

The head and neck are usually dark grey. The sides and the posterior upper section of the foot are grey. The foot is light grey and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral areas are equipped with bands of muscles that are roughly arranged in a chevron pattern. The mantle border is dark grey, with five more or less developed lobes. The ratio of the lateral and the dorsal lobes varies from specimen to specimen, also in the same population. In some specimens, one of these lobes (either lateral or dorsal) may be totally missing. The walls of the pallial cavity are colourless, without any stripes or spots. A strong pulmonary vein is visible. The jaw is odonthognatous and is very variable in shape, from almost straight to markedly arched. There are many smooth transverse ridges, ranging from 18 to 22 in number. The right ommatophoral retractor is independent from both penis and vagina.

Genitalia

The albumen gland is long and connected to an approximately equally long sperm-oviduct that consists of a prostatic and a uterine portion. The prostatic part extends into a thin vas deferens that is approximately as long as the sperm-oviduct and inserts into the penial complex. The distal portion of the uterine part extends into the free oviduct, turning into a vagina at the level of the duct of the bursa copulatrix. The free oviduct is variable in length and can be as long as the vagina or also three times longer. The duct of the bursa copulatrix is usually thin, approximately as long as the penis and uniform in diameter. It terminates into a roundish bursa copulatrix. The transition area between the duct and the bursa is very sharply delimited, with the duct abruptly widening and turning into the bursa. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually two glands that are approximately equally long and are never branched. A short and thin vaginal appendix arises from the wall of the vagina, just distal of the glandular tuft. The inner surface of the vagina is almost smooth. The atrium is usually moderately long and thin. Its internal walls are smooth. The penial complex consists of a flagellum, an epiphallus (which extends from insertion of the vas deferens to penial retractor muscle) and a penis that inserts into the atrium. The penial flagellum is short, remarkably cylindrical and with a blunt apex. It is usually as long as the epiphallus. Its internal walls are completely smooth. The epiphallus is usually short. Its internal walls are also completely smooth. The retractor muscle is moderately large, strong and variable in length. The penis lacks any muscular or glandular sheath. It is thick-walled and approximately three to four times longer than the flagellum. It is usually cylindrical but sometimes slightly swollen and partially folded up. Sometimes, a thin sheath made of light connective tissue envelopes the distal folded part of the penis. The inner walls of the penis are smooth. The penial papilla is usually small, sometimes swollen at its base, reaching 1/8 to 1/10 of the total length of the penis and is conical in shape. It has smooth external walls, with the opening emerging apically. The channel of the penial papilla is thin and narrow, with somewhat fringed internal walls. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue, which directly connects with the walls of the epiphallus. As all the previous species, the longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward (see Figs 171–181).

Figures 171–181. 

Genitalia and anatomy of Wollastonia klausgrohi sp. n. Casa Velhas, next to the W edge of the old quarry: 171 section of penial papilla 172 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium 173 penial papilla 174, 175 whole genitalia excluding part of OSD, AG and gonads 176 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium 177 section of vagina 178 jaw 179 mantle border 180 penial papilla 181 whole genitalia excluding gonads. Scale bars: 1 mm.

Distribution

Wollastonia klausgrohi sp. n. is found along the Casa Velhas area, just W of an abandoned quarry. The W tip of the quarry (currently not exploited at this part) is located only 10 meters from the type locality. Casas Velhas is located along the road n° 233 in direction of Zimbreiro, 340 m ENE from the Miradouro de Portela, E of Vila Baleira. The species has also been collected at Portela, ca. 300 m WSW of the loc. typ., Capela da Graça and 200 m SE of the type locality. The species seems to occupy less than 2,000 m2. For the distribution see Fig. 182.

Figure 182. 

Distribution of Wollastonia klausgrohi sp. n.

Ecology

Wollastonia klausgrohi sp. n. is commonly found under volcanic rocks of a low stone wall built in an open field in a sloping grassland. The specimens directly aestivate on the lower surfaces of the rocks, frequently forming clusters of individuals attached one to another.

Etymology

Named for our co-author, the German malacologist Klaus Groh from Bad Dürkheim to honour his contributions to the malacology of continental snails on the Mid-Atlantic islands.

Comparison and comments

Wollastonia klausgrohi sp. n. has a shell similar to W. jessicae jessicae sp. n. but differs from that species by a last whorl that is always bicarinate, with the upper keel well-visible. The overall colour of the shell is constantly darker in W. klausgrohi sp. n. More important differences are found in the genital anatomy. The internal walls of the penis, atrium and vagina of W. klausgrohi sp. n. are completely smooth, without any pleating or folding. It also resembles H. bicarinata, which, however, always has a wider and shorter atrium and a shorter vagina. Molecular investigations revealed that W. klausgrohi sp. n. is rather closely related to the morphologically very distinct W. oxytropis, whereas W. jessicae sp. n. is closely related to W. leacockiana that occurs in the western part of Porto Santo. Altough W. klausgrohi sp. n. was not recovered as a monophyletic group in the phylogenetic analyses (Fig. 5), statistical support values are rather low, so that monophyly can also not be excluded. We assume that the resolution power of the used molecular markers is insufficient to separate W. klausgrohi sp. n. and W. oxytropis. However, both taxa can easily distinguished by size, shell shape, ornamentation and genital anatomy (Figs 168181, 183194) and therefore are separated as distinct species here. Their distribution areas partly overlap, so that we can currently not exclude mitochondrial introgression as an explanation for the observed pattern in the phylogenetic tree in Fig. 5. Another explanation could be incomplete lineage sorting/ancestral polymorphism assuming a relatively recent divergence of the two taxa. An approach using population genetic markers could help to resolve these issues, such an approach is, however, beyond the scope of the present investigation.

Status and conservation

Because of the very restricted distribution area, the low number of known subpopulations (Fig. 182) and the probably very small population size as well as potential threats through tourism, goat grazing and especially ongoing quarrying, the species is regarded as Critically Endangered (CR B1a, b(iii), 2a, b(iii)) here.

Wollastonia oxytropis (R. T. Lowe, 1831), comb. n.

Figs 183–187, 188–194, 195

List of synonyms

1831 Helix oxytropis R. T. Lowe: 57, pl. 6 fig. 18.

1846 Helix oxytropis – L. Pfeiffer: 142, pl. 91 figs 12–13.

1847 Helix oxytropis – L. Pfeiffer in L. Pfeiffer 1847–1848: 190.

1854 Helix oxytropis – Reeve in Reeve 1851–1854: pl. 138 fig. 868.

1854 Helix (Ochthphila) oxytropis – Albers: 37, pl. 9 figs 8–10.

1855 Helix (Hystricella) oxytropis – R. T. Lowe: 186.

1867 Helix (Octephila) oxytropis – Paiva: 46.

1878 Helix (Hystricella) oxytropis – Wollaston: 167–168.

1888 Helix oxytropis – Tryon in Tryon and [Pilsbry] 1888: 33, pl. 7 fig. 92.

1894 Geomitra oxytropis – Pilsbry in Pilsbry 1893–1895: 242.

1931 Geomitra (Actinella) oxytropis – Nobre: pl. 2 fig. 3.

1950 Discula (Hystricella) oxytropis – Mandahl-Barth: 31, 55.

1983 Discula (Hystricella) oxytropis oxytropis – Waldén: 267.

2002 Geomitra oxytropis oxytropis – Bank et al.: 124.

2006 Discula oxytropis – Cameron et al.: 40 [partim].

2008 Hystricella oxytropis – Seddon: 79, map 180.

2009 Hystricella oxytropis oxytropis – Groh et al.: 21, fig. 26.

2011 Hystricella oxytropis – Seddon: e.T6728A12801442.

Type material

NHM 1968.546, lectotype, (herewith designated), from loc. typ., ex coll. R. T. Lowe; NHM 1948.7.8.12/1 paralectotype, from loc. typ., ex coll. R. T. Lowe. See Fig. 183 for the original figure of Helix oxytropis R. T. Lowe, 1831 from Lowe (1831: pl. 6 fig. 18) and Figs 184–185 for the lectotype/paralectotype of Helix oxytropis R. T. Lowe, 1831 (Photo: P. Crabb, NHM).

Further material examined

All from Porto Santo, CGK/1, CMN/1, Pico do Maçarico, under stones close to the top, 33°04'00"N/16°18'17"W, 200 m, leg. K. Groh & J. Hemmen, Jul. 10 1983; CKG/2, Pico do Maçarico, under stones close to the top, 33°04'00"N/16°18'17"W, 250–285 m, leg. K. Groh & J. Hemmen, Jul. 10 1983; CGK/2, CMN/1, Pico Novalido, W of Pico do Concelho, under stones, 33°04'43"N/16°18'19"W, 185 m, leg. K. Groh & J. Hemmen, Jun. 29 1983; CGK/5, Pico do Concelho, SW slopes, under stones, 33°04'37"N/16°17'47"W, 200–230 m, leg. K. Groh & J. Hemmen, Jun. 29 1983; CKG/2, slope of the Pico do Maçarico from Serra de Fora via Casas Velhas, 33°04'05"N/16°18'35"W, 100–200 m, leg. K. Groh & J. Hemmen, Jul. 10 1983; CKG/5, Pico do Baixo, W slope, 33°03'45"N/16°17'58"W, 150–210 m, leg. K. Groh & J. Hemmen, Jun. 9 1983; CWDM/25, ridge of Pico do Concelho towards E, under stones in grassland, 33°04'42"N/16°17'56"W, 270 m, leg. W. De Mattia & J. Macor, May 18 2015; CFW 11153/<10, Pico do Concelho, ridge W of the summit, 33°04'43"N/16°18'07"W, 220 m, leg. F. Walther, Apr. 3 2017; ANSP H 11846/10, CMN/2, Pico do Concelho, S slope, 33°04'41"N/16°17'57"W, 280 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 12 1985; ANSP H 11845/3, Pico do Concelho, W slope, 33°04'43"N/16°18'04"W, 250 m, leg. K. Groh & J. Hemmen, Jun. 29 1983; ANSP H 11848/12, Pico Malhada, NW slope, 33°04'00"N/16°18'02"W, 120 m, leg. K. Groh & J. Hemmen, Jul. 7 1983; ANSP H 11851/12, Pico do Macaricos, 33°03'58"N/16°18'13"W, 230 m, leg. K. Groh & J. Hemmen, Jul. 10 1983; ANSP H 11850/3, Pico do Maçarico, SE slope, 33°03'57"N/16°18'11"W, 220 m, leg. J. & C. Hemmen, Jan. 8 1981; ANSP H 11849/7, Pico do Concelho, SW slope, 33°04'42"N/16°17'51"W, 200 m, leg. K. Groh & J. Hemmen, Jun. 29 1983; ANSP H 11849/14, approx. 0.5 km S Serra de Dentro, 33°04'44"N/16°18'26"W, 125 m, leg. J. & C. Hemmen, Jan. 6 1981; ANSP H 11852/9, Pico do Maçarico, NE slope, 33°03'58"N/16°18'09"W, 210 m, leg. K. Groh & J. Hemmen, Jul. 10 1983; ANSP H 11847/11, Pico do Baixo, 33°03'45"N/16°17'57"W, 150 m, leg. K. Groh & J. Hemmen, Jul. 9 1983; ZMH 24293/2, Porto Santo, without exact locality data, ex coll. Altonaer Museum; ZMH 24294/1, Porto Santo, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn.

Locus typicus

Hab. in collibus maritimis Portus Sti.

Original description

From Lowe 1831: H. testa depresso-conoidea, supra planulata, perforata, carinata, tota scabra, fusca, sub-fasciata: spira depresso-conica; sutura distincta; anfractibus planiusculis; ultimi carina acuta, distinctissima, supra marginata sc. exarata vel sulco expressa; omnibus distinctissime confertim granulatis, asperis: umbilico minimo, sub-spirali, aperto: apertura rotundata; peristomate continuo, circinato, disjuncto, reflexo. Axis 2 ¼ lin. Diam. 4. Anfr. 6 ½.

Shell

The shell is dextral and hairless. Its shape is rather flattened, almost discoidal, with shallow sutures. The protoconch is brownish with 2–2.3 whorls. It is almost smooth along the first whorl and shows fine radial striae along its remaining portion. The teleoconch has from 3.3 to 3.8 rapidly increasing whorls. It is violet-dark brown with brick red and/or dark violet shades. The dark areas of the shells are mottled with more or less brown to whitish areas, usually arranged longitudinally and slightly slanting. No band pattern is visible along the upper whorls. On the lower part of the last whorl two dark bands are visible that can be more or less broad. The peripheral band is usually broader, even if often rather blurred. In some specimens, the two bands merge together and form a single broad, dark band. The area around the umbilicus is the lightest in colour. The teleoconch whorls are rather flat, with shallow sutures and without a visible keel. The body whorl shows a strong, single keel that sometimes even bends slightly downwards. This keel is of the same colour as the remaining shell and its ornamentation pattern is also not markedly different from that of the rest of the shell’s surface. Contrary to most other Hystricella and Wollastonia species, the keel does not have the appearance of a rough chord. The surface of the teleoconch is ornamented with very fine, irregularly spaced growth lines and regularly arranged, very densely set small tubercles. The last whorl is usually large, contributing approximately 50% to the total shell height and descending near the aperture. The umbilicus is open, eccentric, and measures approximately 10% of the maximum shell diameter. The aperture is elliptical, with a faint thickening along the columellar portion of the stoma. This thickening can also extend as far the parietal side of the aperture. The peristome is continuous, thin, slightly reflected, with the columellar margin somewhat thicker and more reflected (see also Figs 186–187).

Figures 183–187. 

Shells of Wollastonia oxytropis. 183 original figure of Helix oxytropis R. T. Lowe, 1831 from Lowe (1831: pl. 6 fig. 18) 184 lectotype of Helix oxytropis R. T. Lowe, 1831, NMH 1968.546 ex coll. Lowe 185 paralectotype 186, 187 recent specimens from Pico do Concelho. Scale bar 1 mm.

Measurements

D 6.8 ± 0.2 mm (range 7.5–8.0 mm); H 4.9 ± 0.4 mm (range 4.4–5.5 mm); FW 2.7 ± 0.2 mm (range 2.3–3.0 mm); PA 35.8 ± 6.9° (range 33.6–39.3°); DU 0.5 ± 0.05 mm (range 0.4–0.6 mm); NT 89 ± 14 (range 96–61); NW 5.6 ± 0.3 (range 5.3–5.9) (n = 25). Ratio D/H 1.4; ratio FW/H 0.6.

Body

As in the genus description. Wollastonia oxytropis tends however, to have an overall darker body colouration than the other Wollastonia species.

Genital anatomy

The albumen gland is long and thin and is connected to an approximately twice as long sperm-oviduct. The thin vas deferens is roughly 1.5 times longer than the penial complex. The free oviduct is as long as the vagina. The duct of the bursa copulatrix is thin, approximately as long as the penial complex and uniform in diameter. It ends in a roundish bursa copulatrix. The transition area between the duct and the bursa itself is sharply delimited, with the duct abruptly widening and turning into the bursa. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually three glands that are approximately equally long and very rarely branched. A short and thin vaginal appendix arises from the wall of the vagina, just distal of the glandular tuft. The internal walls of the vagina are smooth, as are those of the atrium. The atrium is relatively long and thin. The penial flagellum is very short, cylindrical, has a somewhat blunt to slightly pointed apex, and is usually much shorter than the epiphallus. The epiphallus is approximately as long to slightly longer than the penis. Its internal wall is equipped with irregular longitudinal pleats. The retractor muscle is rather large, strong and of variable length. The penis misses any muscular or glandular sheath. It is thick-walled, cylindrical, and slightly swollen at the level of the penial papilla. The inner walls of the penis are smooth. The penial papilla is small and it usually has a blunt shape. It has smooth external walls with the opening emerging apically. The channel of the penial papilla is thin and narrow. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inward. See Figs 188–194.

Figures 188–194. 

Genitalia and anatomy of Wollastonia oxytropis from Pico do Concelho: 188 whole genitalia excluding part of OSD, AG and gonads. Pico do Concelho: 189 section of vagina 190 tip of penial papilla 191 whole genitalia excluding part of OSD, AG and gonads 192 mantle border 193 ornamentation of the inner walls of the flagellum, the penial complex, the vagina and the genital atrium 194 jaw. Scale bars 1 mm.

Ecology

Wollastonia oxytropis is found under volcanic stones and rocks, in rock crevices and stone walls built in open, stony fields in sloping grasslands.

Distribution

Wollastonia oxytropis has a quite small distributional range. It is known to live exclusively along the SE part of the main island Porto Santo: Pico do Baixo, Pico do Maçarico, Pico do Concelho and Pico do Novalido. These localities were confirmed by survey performed during the 1980’s and 1990’s (CKG, ANSP, Seddon 2008). During recent field surveys (WDM 2012, 2014, 2015, FW 2017) the species has been found living only along the ridge of Pico do Concelho despite careful searches at the above-mentioned localities. The known distribution is shown in Fig. 195.

Figure 195. 

Distribution of Wollastonia oxytropis. Filled circles refer to recent and open circles to fossil records.

Comparison and comments

Wollastonia oxytropis is clearly distinguishable from all other species belonging to Hystricella and Wollastonia by the presence of only a single keel, the rather flattened, almost discoidal shell with very shallow sutures and the extremely short flagellum in relation to the epiphallus.

Taxonomic remarks

Wollastonia oxytropis is somewhat unusual among the Wollastonia gen. n. species as its genital anatomy is more similar to that of the investigated Discula s. str. species than to that of the remaining Wollastonia gen. n. species. However, in the cox1 phylogeny (Fig. 5) the species is clearly embedded within the Wollastonia gen. n. clade indicating that the similarity in genital anatomy may be the result of convergence. We therefore include the species in Wollastonia gen. n. until more in depth phylogenetic analyses and morphological comparisons of the remaining geomitrinid genera will become available.

Status and conservation

According to the current IUCN assessment (Seddon 2011d) the species is considered Near Threatened (NT). Recent surveys indicate however that the species is clearly declining, both with regard to the distributional range and population size, probably as a result of a decline in habitat quality. The area of occupancy and extent of occurrence is approximately 4 km² and the species occurs at relatively few localities clustered in the upper parts of two hills in the south-eastern part of Porto Santo. Therefore, the species should be considered as Endangered (EN B1a, b(iii), 2a, b(iii)).

Wollastonia subcarinulata (Wollaston, 1878), comb. n., stat. n.

Figs 196–198, 199

List of synonyms

1878 Helix (Hystricella) oxytropis var.ß subcarinulata Wollaston: 168.

Discula (Hystricella) oxytropis subcarinulata – Waldén: 267.

2002 Geomitra oxytropis subcarinulata – Bank et al.: 124.

2006 Discula oxytropis – Cameron et al.: 49 (1): 40 [partim].

2009 Hystricella oxytropis subcarinulata – Groh et al.: 21, fig. 27.

Type material

NMWC 80.202, Acc 55.158, lectotype (herewith designated), from loc. typ., ex coll. Melvill-Tomlin, ex coll. T. V. Wollaston, Porto Santo, Madeira (Fig. 196).

Figures 196–198. 

Shells of Wollastonia subcarinulata. 196 lectotype, NMWC 80.202, Acc 55.158; 197–198 specimens from Barbinha, Quaternary aeolinites. Scale bar 1 mm.

Further material examined

All from Porto Santo, CKG/2, Barbinha, Quaternary aeolinites, layer 3, 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh, Jul. 4 1983 and Jul. 5 1983; CKG/3, Barbinha, Quaternary aeolinites, layer 2, 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh, Jul. 4 1983 and Jul. 5 1983; CKG/8, Barbinha, Quaternary aeolinites, layer 4, 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh, Jul. 4 1983 and Jul. 5 1983; CKG/2, south coast, ditch at the in 1985 new built harbour E Vila Baleira, lens of Quaternary calcareous aeolinite within a marine sandy beach terrace (nowadays beyond the quay of the harbour), 33°03'50"N/16°18'56"W, 0–1.5 m, leg. J. Gerber, K. Groh & J. Hemmen, Aug. 1985; CWDM/8, Porto Santo, excavated mud walls behind the cart speedway E of the new harbour of Porto Santo, 33°03'48"N/16°18'22"W, 30 m, leg. W. De Mattia & J. Macor, May 24 2015; CWDM/9, E of Vila Baleira, S slope of the hill above Vale do Touro, 50 m W of the oil tanks, excavated Quaternary mixed gravel, 33°03'47"N/16°19'26"W, 24 m, leg. W. De Mattia & J. Macor, May 24 2015; CWDM/20, Pico do Baixo, E entrance of the tunnel, Quaternary mud deposit, 33°03'44"N/16°17'45"W, 20 m, leg. W. De Mattia & J. Macor, May 24. 2015.

Locus typicus

Porto Santo, Madeira.

Original description

From Wollaston 1878: var. β. subcarinulata – Major, spira magis elevata, ad apicem paulo magis acuta, anfractibus in medio obsolete subcarinulato. – Long. axis 2½ lin.; diam. 3½.

Redescription of shell

Shell large for the genus, with 5.9 regularly increasing whorls, the protoconch with 2.5 whorls. The form of the shell is flat conical, the slightly convex teleoconch whorls separated by a rather shallow but distinct, simple suture. The body whorl shows a distinct, rounded keel, which is enforced by a concave impression below the periphery. The last whorl measures 70%, the penultimate whorl 10% of the total shell height. The lower part of the body whorl is beneath the significantly marked periphery in frontal view first significantly concave, later moderately convex. The keel of the body whorl is located in the upper part of its total height. The aperture, which is inclined to the vertical axis of the shell in an angle of 69° and is descending in its last 5% in an angle of 36° to the horizontal axis, is horizontally elliptic; towards the umbilical region a bit flattened. Its width measures 45% of the total shell width and its height 44% of the total shell height. It has a peristome that is completely detached from the body whorl. The lip is distinctly reflected and very wide at its basal and columellar sides. The eccentric umbilicus, which measures 13% of the total shell width, is shaped like a pinhole in the penultimate whorl and is completely closed in the earlier whorls. The protoconch is smooth, the teleoconch shows a number of oblique radial ribs, 10 in the penultimate quadrant of the body-whorl and is additionally covered by numerous small, round tubercles. The number of tubercles in the standard-quadrate of the base is 108. There is a yellowish hue of colouration in the teleoconch; the keel usually distinctly lighter in colour. See Figs 197–198.

Measurements

D 8.3 ± 0.3 mm (range 8.0–8.8 mm); H 6.1 ± 0.3 mm (range 5.8–6.4 mm); FW 4.1 ± 0.2 mm (range 3.9-4.2 mm); PA 48.2 ± 5.4° (range 42.6–54.4°); DU 0.6 ± 0,06 mm (range 0.5–0.7 mm); NT > 100; NW 5.6 ± 0.1 (range 5.5–5.7) (n = 25). Ratio D/H 1.4; ratio FW/H 0.5.

Distribution

Wollastonia subcarinulata is known from the Quaternary mud and slope deposits along the southern slopes of the eastern part of Porto Santo, from Vale do Touro to the area around the tunnel of Ponta da Galé beneath Pico do Baixo. See map in Fig. 199.

Figure 199. 

Map of the distribution of Wollastonia subcarinulata.

Comparison and comments

Wollastonia subcarinulata can be confused with other, rather large-sized species of the genera Hystricella and Wollastonia like H. echinoderma, W. vermetiformis and W. falknerorum sp. n., from which it can be distinguished, however, by the lack of a second keel, the rounded shape of the keel and a much finer sculpture as well as a more depressed conical form. From similar sized W. inexpectata it is distinguishable by the wider umbilicus, a flatter form, the keeled instead of angled periphery and a coarser granulation. From the recent W. oxytropis it can be distinguished by the larger size, the wider umbilicus, the more convex teleoconch whorls that are separated by a more distinctly marked suture, the finer granulation, and the wider aperture.

Taxonomic remarks

The species is included in the genus Wollastonia because of its size and surface sculpture that is similar to W. oxytropis, as a variety of which it was described by Wollaston (1878). Subsequent authors, except Cameron et al. (2006), recognised the taxon as a subspecies of W. oxytropis.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Wollastonia inexpectata De Mattia & Groh, sp. n.

Figs 200–202, 203

Type material

SMF 348930, holotype, from loc. typ., leg. W. De Mattia, May 23 2015 (see Fig. 200); NMWC 80.202 Acc. 55 158/1 PT as “Geomitra oxytropis Lowe var. subcarinulata Woll. Porto Santo” (Figs 201–202).

Figures 200–202. 

Shells of Wollastonia inexpectata sp. n. 200 holotype, SMF 348930 201 paratype NMWC 80.202 Acc. 55 158 202 label of the lot NMWC 80.202 Acc. 55 158. Scale bar 1 mm.

Locus typicus

N of airport, end of the runway towards Fonte de Areia, Quaternary calcareous sand deposit, 33°05'25"N/17°20'58"W, 99 m.

Etymology

Wollastonia inexpectata sp. n. was unexpectedly found during intensive field researches at Fonte da Areia when looking for H. echinoderma.

Diagnosis

Shell large for the genus, solid and conical. Whorls rounded, with deep sutures. The shell’s surface covered with small and densely set tubercles. Body whorl with a peripheral, rounded keel. Other teleoconch whorls without visible keel. Umbilicus narrow but open. Last whorl descending toward the aperture. Aperture oval with continuous peristome.

Description of the shell

The shell is large for the genus and rather conical, with 6.3 regularly increasing whorls. The protoconch has 1.7 smooth whorls. The teleoconch whorls are distinctly convex and separated by a slightly impressed but simple suture. The body whorl measures 64% and the penultimate whorl 14% of total shell height and is descending towards the aperture in its last 5% in an angle of 36°. It has a rounded angulation in its upper third (in relation to total shell height) that is emphasised by a narrow, only slightly concave impression below the periphery. The lower part of the body whorl (beneath the periphery in frontal view) is otherwise rather convex. The aperture is regular elliptical, measuring 49% of the total shell width and 29% of the total shell height. It is inclined to the vertical axis of the shell in an angle of 57°. The peristome is completely detached from the body whorl, expanded and distinctly reflected, especially in its basal and columellar part. The umbilicus is eccentric, closed in the early whorls, but pinhole-like in the body whorl, measuring 5% of the maximum shell diameter. The sculpture of the teleoconch consists of oblique radial ribs (10 in the penultimate quadrant of the body whorl) and numerous, small roundish tubercles (132 in the standard square basal surface of the shell). The colour is only preserved as a yellowish hue on the teleoconch, a slightly darker yellowish, narrow spiral band in the middle of the base and a lighter marked keel. See Figs 200–202.

Measurements

D 8.6 mm; H 6.7 mm; FW 4.6 mm; PA 41.2°; DU 0.6 mm; NT 132; NW 6.6 (n = 1). Ratio D/H 1.3; ratio FW/H 0.7.

Distribution

The species is only known from the type locality. A second specimen is known from another unidentified locality in Porto Santo and housed at the NMW. The distribution is shown in Fig. 203.

Figure 203. 

Distribution of Wollastonia inexpectata sp. n.

Comparison and comments

Wollastonia inexpectata sp. n. is superficially similar to H. echinoderma, or W. vermetiformis and W. falknerorum sp. n. but is readily distinguishable from these species by the lack of a second keel, its much finer sculpture, narrower umbilicus and regular conical form. From H. echinoderma it can also be distinguished by its regular convex and not stepped whorls and the regular elliptical rather than oblique ovate aperture. From the similarly sized W. subcarinulata it differs in the narrower umbilicus, the presence of a rounded keel, the finer granulation and the higher shell in relation to its width.

Taxonomic remarks

Wollastonia inexpectata sp. n. is included in the genus Wollastonia because it is similar to W. oxytropis in size and surface sculpture. It is noteworthy that the similarly large-sized Hystricella echinoderma most probably also originates from the Quaternary deposits in the north of the island, and likewise is extremely rare there.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Callina R. T. Lowe, 1855

Helix (Callina), Wollaston (1878).

Helix (Tectula), sensu Albers (1854) and Paiva (1867), partim.

Geomitra (Actinella (Callina)), Pilsbry (1893–1895), partim.

Discula (Callina), Mandahl-Barth (1950), Seddon (2008) and Bank et al. (2002).

Callina, Waldén (1983) and Schileyko (2005).

Type species

Helix [Helicella] rotula R. T. Lowe, 1831 by monotypy.

Description of the genus

Shell. The shell is dextral, solid, hairless, and it is usually discoidal to tectiform in shape. The protoconch is dark brown, with 1.4 to 1.9 whorls. It is almost smooth along the first whorl and shows radial striae along its remaining portion. The teleoconch has from 5.3 to 6.6 rapidly increasing whorls. It is corneous brown in colour on the upper side, mottled with scattered, light-brown small areas. One chestnut band is visible along the last three whorls. On the underside of the last whorl two brown bands are visible. The extent of these bands can be variable, either both of them very thin or the peripheral band very broad. Sometimes a number of thinner additional bands are present next to the main peripheral band or, less frequently, no bands are present at all on the underside of the last whorl. The peri-umbilical area is usually the lightest in colour. The spire is broadly conical, making the shell appear discoidal to tectiform. The periphery of the last whorl is either keeled, angled or rounded. The keel is often very distinct and may be slightly bend downwards. The keel is usually lighter in colour than the remaining surface of the whorls, being light brown to whitish. The external upper surface has very fine but clearly visible, relatively regularly spaced growth lines. Regularly disposed, very small, drop-like tubercles are present all over the teleoconch, especially along the growth lines. The dimensions of the tubercles remain quite stable along the whorls and also their density is approximately the same on all teleoconch whorls. The underside of the last whorl is also equipped with tubercles. The last whorl is only slightly wider than the penultimate whorl, and only slightly descending near the aperture. The umbilicus can either be completely closed or widely open (up to 1/5 of the maximum shell diameter). The aperture is elliptical. The lower palatal side of the last whorl shows a strong callous immediately behind the aperture or none. The peristome is interrupted along the palatal area, and it is only slightly reflected along the lower section. The palatal area never shows any kind callosities or thickenings.

Body. Very similar to Wollastonia gen. n. Head and neck are usually grey to dark grey. The sides and the posterior upper section of the foot are whitish to grey. The foot is whitish and the sole is longitudinally divided into three areas. The central area is smooth, whereas the two lateral portions are equipped with bands of muscles that are roughly arranged in a chevron pattern. The mantle border is dark grey, with five more or less well-developed lobes. In some specimens, one of these lobes (either lateral or dorsal) may be totally missing. The walls of the pallial cavity are colourless without any stripes or spots. A strong pulmonary vein is visible. The right ommatophoral retractor is independent from both penis and vagina.

Genitalia. The general arrangement of the genitalia is semi-diaulic monotrematic. A convoluted hermaphroditic duct arises from the gonad. The albumen gland is long and thin and connected to an approximately twice as long sperm-oviduct that consists of a prostatic and a uterine portion. The prostatic part extends to a thin vas deferens, which is approximately twice as long as the sperm-oviduct and which is terminating in the penial complex. The distal portion of the uterine part extends into the free oviduct, which transforms into a vagina at the level of the duct of the bursa copulatrix. The free oviduct is approximately as long as the vagina. The duct of the bursa copulatrix is very wide, approximately as long as the penial complex and usually uniform in diameter. It ends with an oval bursa copulatrix. The transition area between the duct and the bursa itself is not sharply delimited but rather gradually widens. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually two, equally long and very rarely branched glands present. A vaginal appendix arises from the vagina’s wall, just distal of the glandular tuft. Very smooth, rather wide, and little elevated, irregularly spaced pleats run longitudinally along the inner surface of the vagina, which reach into the genital atrium but not as far as the genital orifice. The atrium is short and wide. Its internal walls are smooth. The penial complex consists of a flagellum, an epiphallus (which extends from insertion of the vas deferens to the penial retractor muscle) and a penis that inserts into the genital atrium. The penial flagellum is short, cylindrical and with a pointed apex. It is usually ¼ as long as the epiphallus. Its internal walls are completely smooth. The epiphallus is usually ⅓ longer than the penis. Its internal walls are equipped with 20–25 very fine, elevated, longitudinal pleats. The retractor muscle is strong and approximately half as long as the epiphallus. The penis lacks any muscular or glandular sheath. It is extremely thick-walled and approximately ⅔ as long as the epiphallus. It is cylindrical and slightly swollen in its distal portion. The inner walls of the penis are smooth. The section where the rather large penial papilla is located is usually detectable from outside by virtue of a circular swelling corresponding to the origin of the papilla itself. The penial papilla is approximately half as long as the entire penis. It is conical to subcylindrical in shape and has smooth external walls, with an apically emerging opening. The channel of the penial papilla is thin and narrow. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla (Fig. 226) shows that its walls are the continuation of the penial walls that abruptly bend inwards. See also Schileyko (2005).

Jaw and radula. The jaw and the radula of Callina are very similar to those of Hystricella and Wollastonia. Only the number of the lateral and marginal teeth may be slightly higher: 21 to 29. They do not differ markedly from each other, i.e. their shape gradually changes from the first laterals towards the marginals. The jaw is odontognathous and very variable in shape, from almost straight to markedly arched. There are many smooth transverse ridges, ranging from 9 to 10 in number. For jaws and radulae of Callina species, see Figs 205–207.

Distribution

The genus Callina is endemic to the Island of Porto Santo (Madeiran Archipelago, Portugal). It is distributed along the central-eastern area of the main island. It is not present on the offshore islets. It is only present east of the line Vila Baleira-Dragoal-Camacha-Porto de Salemas. For distributional maps of Callina species, see Figs 204, 214, 217 and 224.

Figure 204. 

Distribution of the genus Callina. Filled circles refer to recent and open circles to fossil records.

Figures 205–209. 

205, 206 radula and jaw of Callina rotula from Ribeira da Areia 207 radula and jaw of Callina bulverii 208 original figure of Helix rotula R. T. Lowe, 1831 (from Lowe 1831: pl. 6 fig. 10) 209 lectotype of Callina rotula, ANSP 97116. Scale bar 1 mm.

Taxonomic remarks

The results of the phylogenetic analyses indicate that Callina is not closely related to Discula R. T. Lowe, 1852 s. lat. as previously supposed but represents a well-supported clade that is closely related to Hystricella and Wollastonia gen. n. The taxon was already elevated to generic rank by Waldén (1995) and Schileyko (2005), although without providing strong morphological evidence for this decision. An isolated position of C. rotula within Discula s. lat. was supposed by these authors on the basis of a closed (or “dot-like” following Schileyko, 2005: 2018) umbilicus. However, our morphological (genitalia) and genetic investigations showed that the closed umbilicus of C. rotula cannot be used as a discriminating feature at the genus-level as the widely umbilicated species C. bulverii also belongs to Callina as supported by the phylogenetic analyses and the peculiar arrangement of pleats on the inner wall of the epiphallus that is equipped with 20–25 very fine, elevated longitudinal pleats (Fig. 211). Contrarily, both Discula s. str. and Discula (Mandahlia) have an epiphallus with 5–7 strong and rather elevated, longitudinal pleats (Figs 228–230). The penial papilla of Callina (Fig. 211 and Fig. 225) always reaches the genital atrium, whereas in Discula s. str. and Discula (Mandahlia) the penial papilla is much shorter and never reaches the genital atrium (Figs 228–229). Discula (Mandahlia) has a very long epiphallus, at least three times longer than the penis (Fig. 230).

Callina rotula (R. T. Lowe, 1831)

Figs 206–209, 210–213, 214

List of synonyms

1831 Helix rotula R. T. Lowe: 53, pl. 6 fig. 10.

1847 Helix rotula – L. Pfeiffer in L. Pfeiffer 1847–1848: 216.

1854 Helix rotula – Reeve in Reeve 1851–1854: pl. 137 fig. 854.

1854 Helix rotula – Albers: 28, pl. 6 figs 16–18.

1855 Helix (Callina) rotula – R. T. Lowe: 183.

1867 Helix (Tectula) rotula – Paiva: 82.

1867 Helix (Tectula) rotula var. α major Paiva: 83.

1867 Helix (Tectula) rotula var. β minor Paiva: 83.

1867 Helix (Tectula) rotula var.γcerina Paiva: 83.

1867 Helix (Tectula) rotulavar.δmonstrosa Paiva: 83.

1878 Helix (Callina) rotula – Wollaston: 151–152.

1888 Helix rotula – Tryon in Tryon [and Pilsbry] 1888: 46, pl. 9 fig. 4.

1894 Geomitra rotula – Pilsbry in Pilsbry 1893–1895: 241.

1922 Ochthephila (Callina) rotula mut. grisea T. D. A. Cockerell: 44–46 [unavailable, infrasubspecific].

1931 Geomitra (Actinella) rotula – Nobre: 81, figs. 30 + 31.

1950 Discula (Callina) rotula – Mandahl-Barth: 36.

1983 Discula (Callina) rotula – Waldén: 267, note p. 273 [partim].

2002 Discula (Callina) rotula – Bank et al.: 124.

2005 Callina rotula – Schileyko: 218–219.

2008 Discula (Callina) rotula – Seddon: 78, pl. 28 fig. E, map 175.

2011 Discula rotula – Seddon: e.T156384A4936221.

Type material

ANSP 97116, lectotype (herewith designated), from loc. typ., ex coll. R. T. Lowe-T. V. Wollaston. For the original figure of Helix rotula R. T. Lowe, 1831 (from Lowe 1831: pl. 6 fig. 10), see Fig. 206. The lectotype of Helix rotula R. T. Lowe, 1831, W = 11.2 mm, is depicted in Fig. 207.

Further material examined

All from Porto Santo. Fossil: CKG/1 juv., SE slope of the Pico de Ana Ferreira, 33°02'36"N/16°22'11"W, 220 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 6 1983; CKG/15, Barbinha, Quaternary aeolinites, 33°04'04"N/16°17'49"W, 8 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 4 1983; CFW 11227/1, Ponta da Galé, E end of the tunnel, 33°03'44"N/16°17'45"W, 30 m, leg. F. Walther & E. M. Gryl, Apr. 1 2017. Recent: CKG/20, NW slope of Pico Juliana, along the upper Ribeira do Pedregal, 33°05'32"N/16°19'25"W, 340 m, leg. K. & C. Groh & J. & C. Hemmen, Jul. 3 1983; CKG/1, Terra Chã, path to forestry house, 33°05'37"N/16°18'03"W, 350 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; CKG/2, region NW of the summit of Pico do Concelho, 33°04'43"N/16°18'01"W, 200–230 m, leg. K. Groh & J. Hemmen, Jun. 29 1983; CKG/1, SW slope of Lombo Branco, 33°05'46"N/16°18'46"W to 33°05'38"N/16°18'13"W, 150–400 m, leg. K. Groh & J. Hemmen, Jul. 8 1983; CKG/5, CMN/5, W slope and crest of the hill W of Pico do Concelho (Pico Novalido?), 33°04'50"N/16°19'37"W, 100–250 m, leg. K. Groh & J. Hemmen, Jun. 29 1983; CKG/10, N slope of Pico do Facho, 33°05'04"N/16°19'25"W, approx. 450 m, Tamarix- and Pinus-forest, leg. K. Groh & J. Hemmen, Jun. 28 1983; CMN/1, Pico de Juliana towards Cabo de Grafa, 33°05'34"N/16°19'11"W, 300 m, leg. K. & C. Groh, Aug. 13 1985; CWDM/5, Ribeira da Areia, serpentine 240 m NNW the quarry, under stones, 33°04'51"N/16°18'41"W, 120 m, leg. W. De Mattia & J. Macor, May 15 2014; CWDM/4, beginning of path to Pico Branco, 33°05'48"N/16°18'54"W, 180 m, leg. W. De Mattia & J. Macor, May 15 2015; CWDM/5, Pico de Cabrita, Pedregal de Dentro, northern slope close to the road, under stones, 33°05'42"N/16°19'23"W, 240 m, leg. W. De Mattia & J. Macor, May 15 2015; CWDM/5, path to Pico Branco, terraced S slope of Pico Branco, under stones, 33°05'35"N/16°18'25"W, 270 m, leg. W. De Mattia & J. Macor, May 16, 2015; CWDM/4, Cabeco dos Bades at the confluence of the two streams, under stones, 33°06'09"N/16°19'25"W, 30 m, leg. W. De Mattia & J. Macor, May 19 2015; CWDM/4, lake S of Ribeira da Serra de Dentro, under stones, 33°04'48"N/16°18'31"W, 70 m, leg. W. De Mattia & J. Macor, May 22 2014; CWDM/5, path to Pico Branco, eastern steep part of path to Pico Branco, under stones, 33°05'29"N/16°18'14"W, 320 m, leg. W. De Mattia & J. Macor, May 22 2014; CWDM/4, Terra Chã-Pico Branco ridge, under stones, 33°05'38"N/16°18'01"W, 335 m, leg. W. De Mattia & J. Macor, May 16 2014; ZMH 120617/2, Pico de Cabrita, 33°05'02"N/16°19'16"W, 460 m, ex coll. W. Fauer, leg. M. Vilella, Mar. 20 1964; ZMH 120616/3, Pico de Juliana, 33°05'32"N/16°19'18"W, c. 360 m, ex coll. W. Fauer, leg. J. & C. Hemmen, Jun. 29 1983; ZMH 110140/15, slopes of Pico do Facho, under stones, c. 33°04'59"N/16°19'25"W, 430 m, leg. E. Clauss, Sep. 22 1992; CFW 10997/11, ZMH 92904/4, southwestern slope of Pico Branco ca. 250 m SW of the top, 33°05'29"N/16°18'13"W, 310 m, leg. F. Walther & E. M. Gryl, Mar. 31 2017; CFW 11107/2, S slope of Pico do Castelo, near parking area, 33°04'42"N/16°20'06"W, 260 m, leg. F. Walther & E. M. Gryl, Apr. 1 2017; CFW 10889/4, ZMH 92889/1, Ribeiro do Pedregal, upper part, downstream of the abandoned houses, 33°05'59"N/16°19'32"W, 120 m, leg. F. Walther, Apr. 2 2017; CFW 10878/4, Pico do Facho, northwestern slope, 33°05'13"N/16°19'38"W, 370 m, leg. F. Walther & E. M. Gryl, Apr. 3 2017; CFW 10835/4, ZMH 92811/1, Casinhas, N of Capela da Graça, 33°04'27"N/16°19'27"W, 150 m, leg. F. Walther, Apr. 4 2017; ZMH 24259/2, Madeira Archipelago, without locality data, ex coll. Altonaer Museum; ZMH 24260/1, Porto Santo, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, ex coll. Dohrn.

Loci typici

[rotula] Hab. in montibus Portus Sti.; not given for the var. α to δ of Paiva. [grisea] Porto Santo, main island.

Original descriptions

[rotula] from Lowe, 1831: H. testa rotundata, conoideo-depressa, supra sub-planulata, subperforata, carinata, scabra, nitidiuscula, fasciata: spira conoidea, obtusissima; sutura obsoleta; anfractibus planis, transverse striatis et granulatis; ultimo acute carinato, carina ad peristoma obsoleta: aperture lunata, extrorsum dilatata; peristomate intiis incrassato, acuto, sub-expanso; ad angulum internum reflexo, calloso, perforationem obtegente. Axis 3 lin. Diam. 6. Anfr. 8; from Paiva 1867: [var. α major] testa distincto fasciata, ampliore; [var. β minor] testa duplo minore, fasciis angustioribus; [var. γ cerina] testa albida, omnio efasciata; [var. δ monstrosa] testa fasciata, anfractibus subsolutis, carina supra suturam valde prominent, rarissima; [grisea]; from Cockerell 1922: Shell pale gray, flecked with creamy white.

Redescription of shell

The shell is dextral, solid, hairless, and it is usually discoidal to tectiform. The protoconch is dark brown with 1.5 to 1.7 whorls. It is almost smooth along the first whorl and shows radial striae along its remaining portion. The teleoconch has from 5.3 to 5.7 rapidly increasing whorls. It is more or less horn brown in colour on the upper side, mottled with small light brown scattered areas. One more or less blurred chestnut band is sometimes visible along the last three whorls. On the underside of the last whorl two brown bands are present that are usually not very broad. The peri-umbilical area is usually the lightest in colour. The spire has a rather conical shape, with the rather flat whorls being separated by a shallow suture. The last whorl is not equipped with a real keel but is rather distinctly angled. The peripheral angulation is often lighter in colour compared to the remaining shell surface, usually whitish to light brown. The surface of the shell has very fine but clearly visible, rather regularly spaced, growth lines. Small tubercles are present on surface of the teleoconch. These tubercles are concentrated along the growth lines, and especially on the underside quite dense. The last whorl is only slightly wider than the penultimate whorl and slightly descending towards the aperture. The umbilicus is completely closed. The aperture is elliptical and the peristome is white and rather solid. A strong callous along the lower palatal side is present, just behind the aperture. The peristome is interrupted along the palatal area and partially reflected along its basal side. The palatal area does not show any callouses or thickenings. See Figs 208–209.

Measurements

D 11.1 ± 0.6 mm (range 10.4–11.8 mm); H 7.2 ± 0.7 mm (range 6.3–8.1 mm); FW 5.1 ± 0.2 mm (range 5.0–5.6 mm); PA 44.0 ± 2.1° (range 42.3–46.4°); NT > 100; NW 7.4 ± 0.3 (range 7.0–7.6) (n = 25). Ratio D/H 1.6; ratio FW/H 0.6.

Body

As in the genus description.

Genital anatomy

A convoluted hermaphroditic duct arises from the gonad. The albumen gland is long and thin and is connected to an approximately twice as long sperm-oviduct that consists of a prostatic and a uterine portion. The prostatic part extends into a thin vas deferens which is approximately twice as long as the sperm-oviduct and which inserts into the penial complex. The distal portion of the uterine part extends into the free oviduct, turning into a vagina at the level of the duct of the bursa copulatrix. The free oviduct is approximately as long as the vagina. The duct of the bursa copulatrix is very wide, approximately as long as the penial complex and usually uniform in diameter. It ends in an oval bursa copulatrix. The transition area between the duct and the bursa itself is not sharply delimited but rather gradually widens. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are usually two, equally long and very rarely branched glands present. A vaginal appendix arises from the vagina’s wall, just distal of the glandular tuft. Very smooth, rather widely separated, and little elevated, irregularly spaced pleats run longitudinally along the inner surface of the vagina, reaching the genital atrium but not as far as the genital orifice. The atrium is short and wide. Its internal walls are smooth. The penial complex consists of a flagellum, an epiphallus (which extends from insertion of vas deferens to penial retractor muscle) and a penis that inserts into the genital atrium. The penial flagellum is short, cylindrical and with a pointed apex. It is usually ¼ as long as the epiphallus. Its internal walls are completely smooth. The epiphallus is usually ⅓ longer than the penis. Its internal walls are equipped with 20–25 very fine, and elevated longitudinal pleats. The retractor muscle is strong and approximately half as long as the epiphallus. The penis lacks any muscular or glandular sheath. It is extremely thick-walled and approximately ⅔ as long as the epiphallus. It is cylindrical and slightly swollen in its distal part. The inner walls of the penis are smooth. The section where the large penial papilla is located is usually detectable from the outside by virtue of a circular swelling corresponding to the origin of the papilla itself. The penial papilla reaches half the length of the penis. It is conical to subcylindrical in shape and has smooth external walls. Its opening emerges apically. The channel of the penial papilla is thin and narrow. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla shows that its walls are the continuation of the penial walls that abruptly bend inwards (See Schileyko (2005) and Figs 210–213).

Figures 210–213. 

Genitalia and anatomy of Callina rotula. Ribeira da Areia: 210 whole genitalia excluding part of OSD, AG and gonads 211 ornamentation of the inner walls of the flagellum, the penial complex and the genital atrium 212 penial papilla 213 cross section of penial papilla. Scale bars 1 mm.

Ecology

Callina rotula is commonly found under volcanic rocks scattered on grassland in open fields that are more or less sloping. The specimens aestivate among the soil and are only rarely attached to the lower surface of the rocks.

Distribution

Callina rotula is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal). It is commonly found in the central-northern areas, north of the line Farrobo-Calhau da Serra de Fora. It is not present on the small islets surrounding the eastern side of the main island, namely Ilhéu de Cima and Ilhéu de Cenouras. See the distributional map in Fig. 214.

Figure 214. 

Distribution of Callina rotula. Filled circles refer to recent and open circles to fossil records.

Taxonomic remarks

Waldén (1983: 273) referred to a fossil specimen resembling C. rotula under his remark 72 from the MMF collection. After checking Waldén's specimen in the collection of the MMF and a recently collected shell, this fossil form apparently belongs to a new species that is described below.

Status and conservation

According to Seddon (2011f) the species is considered Least Concern (LC).

Callina waldeni Groh & De Mattia, sp. n.

Figs 215–216, 217

List of synonyms

1983 Discula (Callina) rotula – Waldén: 267, note p. 273 [partim].

Type material

MMF 46276, holotype, from loc. typ.; CWDM/1 PT, Porto Santo, E of Vila Baleira, S slope of the hill above Vale do Touro, 50 m W of the oil tanks, excavated Quaternary mixed gravel, 33°03'47"N/16°19'26"W, 24 m, leg. W. De Mattia & J. Macor, May 24 2015.

Locus typicus

Porto Santo, Quaternary slope deposits in Vale do Touro, Quaternary mixed gravel, 33°03'51"N/16°19'20"W, 30 m.

Diagnosis

Callina species with closed umbilicus and well-rounded rather than angulated or keeled last whorl; granulation arranged along the growth lines and not evenly scattered across the entire shell surface.

Description of the holotype

The shell is dextral, very solid, hairless, and discoidal to conical in shape. The protoconch is dark brown, with 1.3 to 1.6 whorls and almost smooth except for very fine radial striae. The teleoconch has from 6.4 to 6.7 rapidly increasing whorls. It is whitish in colour, probably bleached. The whorls are slightly convex. The last whorl is rather rounded, neither distinctly angled nor keeled. The external upper surface has very fine but clearly visible, irregularly spaced, growth lines. Small scattered tubercles are present on the upper surface of the teleoconch. These tubercles are arranged along the growth lines. Small and rather densely set (exclusively along the growth lines) tubercles are also present on the underside of the last whorl. The last whorl is only slightly wider than the penultimate whorl and only slightly descending towards the aperture. The umbilicus is closed. The aperture is more or less elliptical and the peristome is white and very solid. A strong callous is present along the lower palatal side just behind the aperture. The peristome is interrupted along the palatal area and partially reflected along its basal portion. The palatal area does not show any callouses or thickenings.

Measurements

D 15.7 ± 0.1 mm (range 15.6–15.8 mm); H 9.1 ± 0.3 mm (range 8.9–9.2 mm); FW 5.6 ± 0.2 mm (range 5.5–5.7); PA 52.4 ± 2.4° (range 51.2–54.4°); NW 7.9 ± 0.3 (range 7.7–8.1) (n = 2). Ratio D/H 1.7; ratio FW/H 0.6.

Distribution

Callina waldeni sp. n. is only known from the locus typicus. See map in Fig. 217.

Taxonomic remarks

Waldén (1983: 273) reported in note 72: “A single giant, subfossil specimen (diam. maj. = 15.8 mm, H = 8.9 mm, whorls: 7.9) has been found in Vale do Touro, Porto Santo (Voucher specimen in Funchal Museum)”. Waldén clearly introduced the fossil specimen of the MMF collection (n° 46276) as belonging to Callina rotula as also reported in the original museum label depicted in Fig. 215. Callina waldeni sp. n. differs from C. rotula by its larger dimensions and a more conical shape, with slightly more convex whorls. The body whorl is not distinctly angled but rather well rounded. The tubercles are only arranged along the growth lines and not scattered on the entire surface of the shell. The aperture is also less elliptical.

Callina waldeni sp. n. is currently the only known fossil representative of the genus.

Figures 215–216. 

Shells of Callina waldeni sp. n. 215 holotype, MMF 46276 216 paratype from E of Vila Baleira, S slope of the hill above Vale do Touro. Scale bar 1 mm.

Figure 217. 

Distribution of Callina waldeni sp. n.

Status and conservation

Extinct before the islands’ scientific exploration in the 19th century, possibly already before human settlement.

Callina bulverii (W. Wood, 1828), comb. n.

Figs 218–219, 220–226, 227

List of synonyms

1828 Helix bulverii W. Wood: 25, pl. 8 fig. 82.

1831 Helix Bulveriana R. T. Lowe: 44–45, pl. 5 fig. 11.

1838 Helix rota Potiez & Michaud: 106–107.

1847 Helix Bulweriana – L. Pfeiffer in L. Pfeiffer 1847–1848: 208.

1852 Helix [Discula] Albersii R. T. Lowe: 117.

1853 Helix Bulverii – L. Pfeiffer: 161.

1853 Helix Bulverii var β – L. Pfeiffer: 161.

1854 Helix Bulveriana – Reeve in Reeve 1851–1854: pl. 136 fig. 849.

1854 Helix [Tectula] Bulwerii – Albers: 24, pl. 4 figs 12+13, 16–18, pl. 5 figs 1–3.

1854 Helix [Tectula] Bulwerii var. γ – Albers: 24, pl. 4 figs 16–18.

1854 Helix [Tectula] Bulwerii var. pallidior Albers: 91, pl. 4 figs 14–15.

1854 Helix [Discula] Bulveriana – R. T. Lowe: 192.

1854 Helix [Discula] Albersii – R. T. Lowe: 192.

1867 Helix [Tectula] Bulweriana – Paiva: 95.

1867 Helix [Tectula] Bulweriana var.βmajor Paiva: 95.

1888 Helix Bulweri – Tryon in Tryon and Pilsbry 1888: 42, pl. 9 fig. 88.

1894 Geomitra Bulweri – Pilsbry in Pilsbry 1893–1895: 243.

1922 Ochthephila (Tectula) bulverii mut. albescens T. D. A. Cockerell: 45 [unavailable, infrasubspecific].

1931 Geomitra (Actinella) Bulweri – Nobre: 100–102, figs. 47, 48.

1950 Discula (Discula) bulweri bulweri – Mandahl-Barth: 469: 36.

1950 Discula (Discula) bulweri albersi – Mandahl-Barth: 36, pl. 2 fig. 5, pl. 4 fig. 4, pl. 9 fig. 7.

1983 Discula (Discula) bulweri – Waldén: 20: 267.

1983 Discula (Discula) albersi – Waldén: 20: 267.

2002 Discula (Discula) bulverii – Bank et al.: 123.

2008 Discula (Discula) bulverii – Seddon: 78, pl. 29 fig. G, map 170.

2011 Discula bulverii – Seddon: e.T6725A12800858.

Type material

Despite intensive research in multiple museum collections (NHM, NMW, MMUE, ANSP, NHC, NMS, OUMNH, RAM, SMF) that could have held the type material of the taxon, no such material could be traced and therefore we deem it reasonable to assume that the type material is lost. To stabilise the present interpretation of Helix bulverii W. Wood, 1828 and to clarify its taxonomic status we designate a neotype here, which is deposited in the collection of the SMF, Frankfurt a. M. under SMF 348938, W. De Mattia & J. Macor, May 15 2014. See Fig. 218. The neotype is consistent with the figure in Wood (1828: pl. 8 fig. 82) in shape, the development of the aperture and the umbilicus and colouration. The taxon was originally described from the Madeiras (= Madeira Archipelago) without more detailed locality data, which is consistent with origin from Porto Santo of the specimen selected as neotype.

Figures 218–219. 

Shells of Callina bulverii. 218 neotype, SMF 348938 219 specimen from Zimbreiro. Scale bar 1 mm.

Loci typici

[bulverii] Porto Santo, S slope of Pico do Facho, along path at the S border of the pine wood, under stones, 33°04'52.47"N/16°19'25.95"W, 355 m a.s.l. (through the designation of the neotype); [Bulveriana] Hab. in montibus Insulae Portus Sti.; [rota] Hab. Porto-Santo (Afrique); [Albersii] Hab. in Portu Sto.; [Bulwerii] Habitat in Portosanto, in locis siccis, aridis; [Bulwerii var. γ] unknown, as not mentioned; [pallidior] unknown, as not mentioned; [Bulweriana]: Habitat copiose in insulae Portosancti aridis, saxosis sub lapidibus ad montes Pico do Facho, Pico dos Maçaricos, prope N.[ossa] Senhora da Graça, Casas Velhas, Cabeço das Fontainhas, fossil ad Zimbral d’Aréa rarior; [Bulweriana var. β major]: prope N.[ossa] Senhora da Graça, rarissima; [albescens] Slopes of Pico do Facho, Porto Santo.

Further material examined

All from Porto Santo. Fossil: ZMH 110291/5, coastal slopes at street between harbor and SE coast, 33°03'46"N/16°18'21"W, c. 10–50 m, Sep. 22 1992 and Jul. 1 1996, leg. E. Clauss; ZMH 110292/1, coastal slopes at street from harbor towards the east, 33°03'46"N/16°18'21"W, c. 10–50 m, Sep. 22 1992, leg. E. Clauss. Recent: CWDM/12, S slope of Pico do Facho, along path at the S border of the pine wood, under stones, 33°04'52"N/16°19'26"W, 355 m, leg. W. De Mattia & J. Macor, May 15 2014; CWDM/8, Pico de Juliana, under stones, 33°05'31"N/16°19'20"W, 365 m, leg. K. & C. Groh, Oct. 27 1980; CKG/10, Zimbreiro, 200 m SW of the village, near the road turn serpentine, under stones, 33°04'16"N/16°18'53"W, 90 m, leg. W. De Mattia & J. Macor, May 2014; CKG/2, summit of smaller hill and saddle below the Pico do Maçarico, 33°03'58"N/16°18'29"W, approx. 160 m, leg. K. Groh & J. Hemmen, Jul. 2 1983; CKG/2, upper Ribeira do Formosa between Covao and Serra de Fora, 33°05'02"N/16°19'14"W, 140 m, leg. K. & C. Groh & J. & C. Hemmen, Jun. 19 1983; CKG/9, bank of the road above the quarry above the Miradouro da Portela; walls and pasture above Capela da Graça towards the rocky slopes of the Pico do Facho (Motos de Fora), 33°04'42"N/16°20'01"W, 250–400 m, leg. K. & C. Groh & J. & C. Hemmen, Jun. 23 1983; ZMH 120607/4, Pico do Castelo, 33°04'42"N/16°20'01"W to 33°04'51"N/16°20'03"W, 350–430 m, leg. J. & C. Hemmen, ex coll. W. Fauer, Jul. 11 1983; ZMH 120608/2, Graça, 33°04'27"N/16°19'24"W, 190 m, leg. Balka, ex coll. W. Fauer, Jun. 25 1964; CKG/3, Pico Juliana towards Cabo de Grafa, 33°05'34"N/16°19'11"W, 300 m, leg. C. & K. Groh, Aug. 13 1985; CKG/1, Pico do Castelo, 33°04'42"N/16°20'01"W to 33°04'51"N/16°20'03"W, 350–430 m, leg. C. &. K. Groh, Aug. 13 1985; CFW 10782/<10, Casinhas, N of Capela da Graça, 33°04'27"N/16°19'29"W, 150 m, leg. F. Walther, Apr. 4 2017; CFW 10783/<10, CMN/3, ZMH 92919/>10 (tissue only), ridge between Zimbreiro and the quarry, 33°04'13"N/16°18'49"W, 110 m, leg. F. Walther, Apr. 3 2017; CFW 10847/<10, ZMH 92830/11, Casa Velhas, next to the W edge of the old quarry, 33°04'06"N/16°18'52"W, 125 m, leg. F. Walther, Apr. 3 2017; CFW 10918/7, Pico do Concelho, NW slope above water reservoir, 33°04'46"N/16°18'19"W, 170 m, leg. F. Walther, Apr. 4 2017; CFW 11126/<10, ZMH 92905/4, 200 m SW of the Zimbreiro near the road turn serpentine, 33°04'15"N/16°18'54"W, 100 m, leg. F. Walther, Mar. 31 2017; ZMH 92812/2, Pico do Maçarico, small saddle at the NW ridge, leg. 33°03'58"N/16°18'15"W, 220 m, F. Walther, Apr. 3 2017; ZMH 24261/2 [as albersi], Porto Santo, without exact locality data, ex coll. Altonaer Museum, ex coll. O. Semper, leg. Wessel; ZMH 24264/2, Porto Santo, without exact locality data, ex coll. Altonaer Museum.

Original descriptions

[bulverii] only name and figure; [Bulveriana] from Lowe (1831): H. testa rotundato-depressa, hemisphaerica, rotata, supra planulata, acutissime carinata, tenui, nitidiuscula, tota minutissime et confertim granulata, fusco-castanea, supra fasciata; spira convexo-depressa, plus minus elevata, obtusissima; sutura obsoleta; anfractibus planis, acquis, quasi attritis vel confluentibus, ultimi carina acutissima, tenui, supra sulco exarata, limbata; umbilico patulo, spirali, profundo; apertura rotundato-lunata; peristomate interrupto, ad umbilicum incrassato, reflexo. Axis 3–2½ lin. Diam. 7–8. Anfr. 8–7; [rota] from Potiez & Michaud (1838): Cette coquille est plus petite que l’hel. lapicida à laquelle elle peut être comparée par sa forme générale; elle est carénée et ombiliquée comme elle, sa couleur est à peu près la même, mais elle diffère par la disposition des taches brunes; le péristome n’est ni continu, ni évasé , et l'avant-dernier tour fait une saillie dans l’ouverture. Toute la coquille est lisse et luisante à la première vue, mais à la loupe, elle est finement chagrinée et striée; la carène est très tranchante. Hab. Porto-Santo (Afrique.); [Bulverii var. β] from Pfeiffer (1847): Paulo minor, corneo-lutea , subtiliter marmorata et fasciata, anfractu ultimo subtus convexiore, carina minus compressa; [Albersii] from R. T. Lowe, 1852: Species eximia inter insigniores, in honorem cl. J. C. Albers, M. D., Helicosophi peritissimi necnon taxophilorum omnium optime meriti dicata. H. Bulveriana similis differt testa subminore solidiore trochiformi colore cerino-corneo magis opaco, minus (praesertim juniore) planato-depressa, subtus convexiore, carina media minus limbato-prominente, apertura ad carinam haud angulata; [Bulwerii] from Albers 1854: Testa umbilicata, depresse conoidea, solidula, leviter striata et eleganter dense granulate, badia, maculis pallidioribus variegate; spira parum elevate, apice obtuse; anfractus 8 regulariter accrescentes, sutura obsolete juncti, ultimus acute limbato-carinatus, subtus planulatus, saturate flavus 1-3 fasciatus, umbilicus mediocris, perspectivus; aperture oblique, elliptico-rotundata, ad carinam angulata; peristoma simplex, marginibus conniventibus, supero recto, basali crassiori, sinuato, ad umbilicus reflexiusculo. Diam. maj. 18, min. 16 ½, al. 8 ½ millim.; [Bulwerii var. γ] from Albers 1854: Testa pallida cornea, striata, sparsim granulate, anfractus ultimus subtus convexus, antice parum descendens, aperture subcircularis. Diam maj. 16, min. 15, alt. 7 millim.; [pallidior] from Albers 1854: only name and figure; [Bulveriana var. β major] from Paiva 1867: β major, spira altissima; [albescens] from Cockerell 1922: Shell greenish-white.

Redescription of the shell

The shell is dextral, hairless, and discoidal to tectiform in shape. The protoconch is whitish to light brown with 2.1 to 2.5 whorls. It is almost smooth along the first whorl and shows fine radial striae along its remaining portion. The teleoconch has from 5.2 to 5.6 rapidly increasing whorls. It is horn brown in colour on the upper side, mottled with scattered, dark or light brown small areas. The surface of the shell is somewhat shiny. One chestnut band is present on the upper side of the teleoconch that is gradually widening and becoming darker towards the body whorl. On the underside of the last whorl one main brown band is present. Sometimes, a number of thinner additional bands are present next to the main band. The peri-umbilical area is usually the lightest in colour. The spire is broadly conical, letting the shell appear tectiform. Along the last whorl a single, distinct keel is present which may be slightly bend downwards. The keel is usually lighter in colour than the remaining surface of the whorls, being whitish to light brown. The upper surface is equipped with very fine but clearly visible, rather regularly spaced, growth lines. Small, drop-like tubercles are scattered all over the teleoconch, but concentrated along the growth lines. The last whorl is only slightly wider than the penultimate whorl and is only slightly descending towards the aperture. The umbilicus is widely open (measuring approximately 10% of the maximum shell diameter). The aperture is elliptical. The lower palatal side of the last whorl may be equipped with a strong callous just behind the aperture. The peristome is interrupted along the palatal area, and it is only slightly reflected along its basal portion. The palatal area never shows any callosities or thickenings. See Fig. 219.

Measurements

D 14.2 ± 1.0 mm (range 13.3–15.6 mm); H 7.5 ± 0.3 mm (range 7.1–7.9 mm); FW 6.2 ± 0.2 mm (range 5.9–6.5); PA 48.0 ± 7.3° (range 44.6–49.4°); NT > 100; NW 7.4 ± 0.2 (range 7.2–7.6) (n = 30). Ratio D/H 1.9; ratio FW/H 0.8.

Body

As in the genus description. Callina bulverii tends to have an overall slightly darker body colouration than C. rotula.

Genital anatomy

The albumen gland is long and thin and is connected to an approximately twice as long sperm-oviduct that consists of a prostatic and a uterine portion. The prostatic part extends into a thin vas deferens which is approximately twice as long as the sperm-oviduct and which inserts into the penial complex. The distal portion of the uterine part extends into the free oviduct and transforms into a vagina at the level of the duct of the bursa copulatrix. The free oviduct is ⅔ as long as the vagina. The duct of the bursa copulatrix is very wide, approximately ½ as long as the penial complex and uniform in diameter. It ends into an oval bursa copulatrix. The transition area between the duct and the bursa itself is not sharply delimited but rather gradually widens. The spermatophore is unknown. One tuft of digitiform glands arises from the proximal part of the vagina. There are two to three, approximately equally long and very rarely branched glands. A vaginal appendix arises from the vagina’s wall just distal of the glandular tuft. Irregularly spaced pleats run longitudinally along the inner surface of the vagina, reaching the genital atrium but extending not as far as the genital orifice. The atrium is short and wide. Its internal walls are smooth. The penial complex consists of a flagellum, an epiphallus, and a penis that inserts into the genital atrium. The penial flagellum is short, cylindrical and has a pointed apex. It is ⅕ as long as the epiphallus. Its internal walls are completely smooth. The epiphallus is twice as long as the penis. Its internal walls are equipped with 20–25 very fine and elevated, longitudinal pleats. The retractor muscle is strong and approximately ½ as long as the epiphallus. The penis is cylindrical, it lacks any muscular or glandular sheath, and it is extremely thick-walled. The internal walls of the penis are smooth. The section where the large penial papilla is located is usually detectable from outside by virtue of a circular swelling corresponding to the origin of the papilla itself. The penial papilla almost reaches the genital atrium and is approximately as long as the penis. It is conical to subcylindrical in shape and has smooth external walls, with the opening emerging apically. The channel of the penial papilla is thin and narrow. The inner lumen of the penial papilla is occupied by a spongy and sturdy tissue which directly connects with the walls of the epiphallus. The longitudinal section of the penial papilla (Fig. 226) shows that its walls are the continuation of the penial walls that abruptly bend inwards. See Figs 220–226.

Figures 220–226. 

Genitalia and anatomy of Callina bulverii. S slope of Pico do Facho: 220 whole genitalia excluding part of OSD, AG and gonads 221 ornamentation of the inner walls of the vagina, the penis and the genital atrium 222 cross section of the duct of the bursa copulatrix 223 penial papilla 224 inner walls of epiphallus 225 cross section of penial papilla 226 longitudinal section of penial papilla. Scale bars 1 mm.

Schileyko (2005: 2018, fig. 2549) depicted the genital anatomy of Callina bulverii, but, except for the penis papilla, only dealt with the outer appearance of the genitalia. Mandahl-Barth (1950) also depicted some anatomical details of C. bulverii, i.e. the foot pedal gland, the digitiform glands, and the vaginal appendix.

Jaw and radula

The jaw has been depicted by Mandahl-Barth (1950).

Distribution

Callina bulverii is endemic to the island of Porto Santo (Madeiran Archipelago, Portugal). It is restricted to the area delimited by the Pico do Facho, Calhau de Serra de Dentro, Portela and Porto dos Frades. It is not present on the small islets surrounding the eastern side of the main island, namely Ilhéu de Cima and Ilhéu de Cenouras. See distribution map in Fig. 227.

Figure 227. 

Distribution of Callina bulverii.

Taxonomic remarks

Although the shell morphology is rather different from the two other Callina species, the very similar genital anatomy and its position in the cox1 tree clearly support the inclusion of the species in the genus Callina. Seddon (2008: 78) thoroughly summarised the nomenclatural vicissitudes of the synonyms of C. bulverii.

Status and conservation

Seddon (2011g) assessed the species as Critical Endangered (CR B2a, b(iii, v)) but because of the wide distribution and high frequency the species should be considered Least Concern (LC).

Figures 228–232. 

Comparison of the inner genitalia of Discula (Discula) and Discula (Mandahlia) species. 228–230 Discula (Mandahlia) tectiformis from summit slopes of Pico do Baixo: 228 cross sections of the penial complex 229 inner walls of penis, atrium and distal vagina 230 inner walls of epiphallus 231–232 Discula (Discula) polymorpha polymorpha from Porto Moniz, Madeira: 231 inner walls of epiphallus, penis, and atrium 232 cross section of penial papilla.

Acknowledgements

We would like to thank Jon Ablett (NHM) for the search for type material and Phil Crabb (NHM) for photographs of syntypes from the Lowe-Wollaston collection, Ruud Bank (Hoogezand, The Netherlands) for advise on nomenclatural problems, Manuel Biscoito (MMF) for the Portoguese translation of the Abstract and photographs of a Callina-specimen, Paul Callomon (ANSP) and Gary Rosenberg (ANSP) for the loan of material from the Hemmen-collection, Jochen Gerber (Chicago, USA) for the images of specimens from his private collection, Holly Morgenroth (RAM) for the search of type material and photographs of possible Wollaston-types in the Linter collection, Barna Páll-Gergely (HNHM), Takahiro Asami (Shinshu University, Japan) and Josef Harl (Vienna, Austria) for assistance in the lab, sequencing and the preparation and SEM images of jaws and radulae, Ted von Proschwitz (NMG) for the loan of material from the Waldén-collection, Frank Walther (Essen, Germany) for making available parts of his collection for investigation, Harriet Wood (NMW) for the search for type material, the access to the collections and photographs of material from the Melvill-Tomlin collection including possible syntypes from the Wollaston collection, and several people for the search for type material, like Mark Blaxter (NHC, UK), Sankurie Pye (NMS, UK), Mark Carnall (OUMNH, UK), Henry McGhie (MMUE, UK).We thank David Allen (IUCN, Cambridge, UK) and Nathalie Yonow (Swansea University, UK) for language improvements and copy-editing. We also would like to thank Frank Walther, Eike Neubert (NMBE, Bern Switzerland) and Luis Javier Chueca (SystBioGen, University of the Basque Country, Vitoria-Gasteiz) for helpful comments on a draft version of the manuscript.

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