The specimens were collected in Morocco and Algeria between 1998 and 2015. Reference specimens from Spain and Portugal could be included. Detailed sampling locations of the investigated specimens are given in Fig. 1 and Table 1. The voucher number and the GenBank accession numbers for the obtained DNA sequences can be found in Table 1. All specimens used in this study are housed in the Natural History Museum Bern, Switzerland.

Figure 1. 

Sampling locations of the investigated specimens. This map was produced with QGIS (2016, v2.18.12) using the Natural Earth data set.

Abbreviations of institution:

MHNL Musée de Confluence, Lyon

MNHN Museum National d’Histoire Naturelle, Paris

NMBE Naturhistorisches Museum, Bern

SMF Research Institute Senckenberg, Frankfurt

For total DNA extraction the Qiagen Blood and Tissue Kit (Qiagen; Hilden, Germany) was used in combination with a QIAcube extraction robot. Ca. 0.5 cm³ of foot tissue was cut from the foot muscle and placed in a mix of 180 µl ATL buffer and 20 µl Proteinase K. It was then incubated for ca. 4 hours at 56 °C in a heater (Labnet, Vortemp 56, witec AG, Littau, Switzerland). For subsequent DNA extraction the QIAcube extraction robot with the Protocol 430 (DNeasy Blood Tissue and Rodent tails Standard) was used. In this study, two mitochondrial markers (COI and 16S) and two nuclear markers (H3 and 5.8 S rRNA+ITS2) were investigated. PCR mixtures consisted of 12.5 µl GoTaq G2 HotStart Green Master Mix (Promega M7423), 8.5 µl ddH₂O, 1 µl forward and reverse primer each, and 2 µl DNA template. In Table 2 the used primer pairs for the PCR are listed. Following PCR cycles were used: for COI 2 min at 94 °C, followed by 35 cycles of 1 min at 95 °C, 1 min at 40 °C and 1 min at 72 °C and finally, 5 min at 72 °C; for 16S 5 min at 95 °C, followed by 45 cycles of 30 s at 95 °C, 30 s at 48 °C and 45 s at 72 °C, and finally, 5 min at 72 °C; for H3 3 min at 95 °C, followed 40 cycles of 1 min at 95 °C, 1 min at 42 °C and 1 min at 72 °C, and finally, 10 min at 72 °C, and for 5.8 S rRNA+ITS2 1 min at 96 °C, followed by 45 cycles of 30 s at 94 °C, 30 s at 50 °C and 1 min at 72 °C, and finally, 10 min at 72 °C (SensoQuest Tabcyclet and Techne TC-512, witec AG, Littau, Switzerland). The purification and sequencing of the PCR product was performed by LGC (LGC Genomics Berlin, Germany). Interpretation of Bootstrap values: 70 to 80 = moderate support; 80 to 90 = well supported; > 90 = high support. Bayesian posterior probabilities: values above 0.95 are significant support.

For the phylogenetic analyses sequences obtained from GenBank were included as outgroups: Arianta arbustorum (Linnaeus, 1758) (Cadahia et al. 2014), Marmorana muralis (OF Müller, 1774), and Allognathus balearicus (Rossmässler, 1838) (= Allognathus hispanicus (Rossmässler, 1838)) (Neiber and Hausdorf 2015). Additionally, sequences of Helix melanostoma Draparnaud, 1801, Theba subdentata subdentata (Férussac, 1821), Massylaea constantina (E Forbes, 1838) and Massylaea vermiculata (OF Müller, 1774) from the study of Bouaziz-Yahiatene et al. 2017 were also included as outgroups. These species were selected to identify the phylogenetic placement of the focal taxa investigated in this study.

For sequence processing and editing the software package Geneious v9.1.8 (Biomatters Ltd) was used. The protein-coding gene fragments of COI and H3 were defined in two data blocks. The first two codon positions were defined as one block and the third codon position as a second block. The non-coding regions from 16S and 5.8 S rRNA+ITS2 were defined as a single data block. Partitionfinder-2.1.1 (Lanfear et al. 2012) was applied for searching optimal evolutionary models for the partitions using the corrected Akaike Information Criterion (cAIC). RAxML plug-in for Geneious (Stamatakis 2006) was implemented for computing ML inference, using Geneious’ plug-in with rapid bootstrapping setting, the search for the best scoring ML tree and 1500 bootstrapping replicates. Bayesian Inference (BI) was performed using Mr. Bayes v3.2.6 ×64 (Huelsenbeck and Ronquist 2001; Ronquist and Huelsenbeck 2003; Altekar et al. 2004) through the HPC cluster from the University of Bern (http://www.id.unibe.ch/hpc). For the concatenated data set, Partitionfinder-2.1.1 was used for finding the optimal evolutionary models for each subset with the model = all function. The Monte Carlo Markov Chain (MCMC) parameter was set as follows: starting with four chains and four separate runs for 20 million generations with a tree sampling frequency of 1000 and a burn in of 25%.

Living animals were killed in boiling water and stored for one day in 80% ethanol. The next day, the ethanol was exchanged and the specimens were stored in the fridge at 5 °C until DNA extraction and dissection. Our experience showed that this procedure maintains the soft tissue and is essential for proper anatomical studies, as well as for the conservation of DNA. The dissection of the snail genitalia took place under a stereomicroscope (Leica MZ12) using thin tweezers and scissors. The genitalia were dissected from the body, spread on a wax bedded bowl, and properly pinned with small needles. The total length of the situs was measured using a calliper (Mitutoyo). Proportions between different parts of the genitalia were estimated using the total situs length as a reference. Additionally, the inner structures of the penis and the epiphallus were investigated. Pictures of the situs were taken with a Leica DFC425 microscope camera using an image-processing program (IMS Client V15Q4, Imagic, Switzerland). The empty shells were imaged using a camera (Canon EOS 50D) in a frontal, lateral, apical, and ventral position. The shell height and shell diameter were measured with perpendicular shell axis with the calliper.

Abbreviations used in the anatomical descriptions and figures:

At atrium

AG albumin gland

AS atrial stimulator

BC bursa copulatrix

BCD diverticulum of the bursa copulatrix

D shell diameter

DS dart sac

Ep epiphallus

Fl flagellum

FO free oviduct

H shell height

HD hermaphroditic duct

MG mucus glands

MRP musculus retractor penis

PA penial appendix

Pe penis

PF penial flap

PP1 proximal penial papilla

PP2 distal penial papilla

PS penis sheath

Va vagina

VD vas deferens

The RAxML analysis of the concatenated data set (Fig. 2) recovered the genus Alabastrina as sister genus to Siretia and Otala. This node is supported with a ML support value of 90. The species A. tistutensis Galindo, 2018 clusters within the five specimens of A. alabastrites (Michaud, 1833). The monophyly of S. pallaryi (Kobelt, 1909) and Otala (and thus the separation of S. pallaryi and Alabastrina) is highly supported (bootstrap value of 99). The monophyly of Otala is not statistically supported (bootstrap value of 61). Within Otala we recovered three major clades, i.e., O. punctata (OF Müller, 1774), O. lactea (OF Müller, 1774), and O. xanthodon (Anton, 1838). The specimen of “Tingitana minettei decussata” (nomen nudum) clusters within the O. xanthodon clade. The monophyly of O. lactea is not statistically supported (bootstrap value of 65). Within O. xanthodon there are some nodes with very low support, especially the node which includes “Tingitana minettei decussata” (NMBE 549840). Otala l. murcica (Rossmässler, 1854) (NMBE-554175 and NMBE-554176 in Figs 2, 3) nests within the O. lactea clade. Both, the separate mitochondrial and nuclear tree show the same topology as the concatenated tree. They can be found in the supplementary material (Suppl. materials 1, 2).

Figure 2. 

Maximum Likelihood (RAxML) tree based on concatenated data set of COI, 16S, H3, and 5.8 S rRNA+ITS2. Numbers represent bootstrap support values from the ML analysis.

Figure 3. 

Bayesian Inference tree based on concatenated data set of COI, 16S, H3, and 5.8 S rRNA+ITS2. Numbers represent Bayesian posterior probabilities.

The Bayesian Inference analysis of the concatenated data set (Fig. 3) recovered the monophyly of Alabastrina. This node is statistically supported (posterior probability of 1). The monophyly of S. pallaryi and Otala and thus the separation of S. pallaryi and Alabastrina is fully supported. There is no difference in both types of analyses in the O. lactea and the O. xanthodon clade. The separate mitochondrial and nuclear trees can be found in the supplementary material (Suppl. materials 3, 4).

The nomenclature of the parts of the genital organs follows Neubert and Bank (2006) and Neubert (2014). In Table 3, the traits of the genital organs are summarised.

1904 Alabastrina Kobelt, in Rossmässler: Iconographie der Land- & Süsswasser-Mollusken, (2) 11: 33, 132, 194 [type species Helix alabastrites Michaud, 1833 by OD].

1904 Alabastra Kobelt, in Rossmässler: Iconographie der Land- & Süsswasser-Mollusken, (2) 11: 100.

Currently, this genus is subdivided in six subgenera (Schileyko 2006). This system is more or less completely based on shell characters and only for a few specimens the morphology of the genital organs has been investigated and published. Schileyko (2006: 1794, fig. 2297B, C) shows the genital organs of Helix hieroglyphicula Michaud, 1833, which is the type species of Michaudia Pallary, 1926 [by original designation]. In his definition of Alabastrina sensu lato, he uses the character state “branches of mucus glands before entering common duct form distinct swellings” (Schileyko 2006: 1792). This interesting trait is not seen in any of the Alabastrina species investigated by us. Holyoak and Holyoak (2017: 426, Table 1) relegate Michaudia into the synonymy of Otala, also based on Schileyko’s figure arguing with the conformity in the structure of the interior of the proximal penis. The assumption by Schileyko (2006) that Alabastrina agrees with Otala on the presence of two penial papillae is wrong.

Without further comment, Holyoak and Holyoak (2017) consider Loxana Pallary, 1899 a separate genus, follow Razkin et al. (2015) in leaving Atlasica Pallary, 1917 as a subgenus of Alabastrina, and omit Lechatelieria Pallary, 1926. Taxon sampling in Razkin et al. (2015) is not sufficient enough to clearly reveal the subgeneric position of Atlasica. Based on our anatomical investigation, the genus Alabastrina can now be newly characterised using the following traits of the genital organs: Penis with a single penial papilla (PP) with a central pore, distal penis with penial flap (PF), proximal penis with a small penial appendix (PA); epiphallus and flagellum of similar length; mucus glands (MG) multifid, branches very long and slender.

Nomenclatural remark: Kobelt established the names Alabastra and Alabastrina simultaneously in the register volume of the “Iconographie”. In this work, he presented a register on the “System der palaearktischen Binnenconchylien”, listing a genus group name together with a single species group name (129 ff.). In the second register (171 ff.), he provided a systematically ordered list with information on all taxa ever published in the “Iconographie”, and affiliated these taxa into the new system as outlined before in register 1. Both registers are accompanied by text dealing with zoogeographic considerations and taxonomic remarks.

The name Alabastra was used three times exclusively on page 100 (in combination with a species list). The name Alabastrina was used on page 33 (zoogeographic context), page 132 (systematic register combined with the species group name alabastrites), page 158 (a list of potential members of Alabastrina including alabastrites), and finally page 194 (amended list of illustrated taxa of Alabastrina sensu Kobelt). According to ICZN 24.2.4 we deem Kobelt to act here as First Reviser, because he consequently used the name Alabastrina in his registers. We interpret the name Alabastra to constitute an erroneous misspelling.

Both genus group names included species lists of differing composition, the name alabastrites was always included (loc. cit.). In the first register, the name Alabastrina was combined with a single species (p. 132). We consider this act a designation of the type species by the original author (OD); Schileyko’s note on the type species selection (2006: 1792) as “monotypy” is erroneous.

Figs 4–8

1833 Helix alabastrites Michaud, Catalogue des testacés vivans envoyés d’Alger par M. Rozet, capitaine au corps royal d’État-Major, au cabinet d’Histoire Naturelle de Strasbourg: 4, figs 6–8 [Oran].

1833 Helix soluta Michaud, Catalogue des testacés vivans envoyés d’Alger par M. Rozet, capitaine au corps royal d’État-Major, au cabinet d’Histoire Naturelle de Strasbourg: 3, figs 9, 10 [Oran].

Type specimens: Helix alabastrites: syntype MHNL 45000690; Helix soluta: syntype MHNL 45000679.

Specimens examined: for sequenced specimens, see Table 1.

Description. The range of the shell diameter of the investigated specimens is between 14.93–22.77 mm and shell height is between 10.85–13.45 mm. The shell of this species is pale and often with dark brown stripes. Some individuals do not show any stripes at all (Figs 4B, 6A). There is none to one tooth found in the aperture.

Figure 4. 

Alabastrina type specimens. A Helix soluta, syntype MHNL 45000679, Oran, Algeria, coll. Michaud, D = 24.15 mm B Helix alabastrites, syntype MHNL 45000690, Oran, Algeria, coll. Michaud, D = 22.48 mm. All photographs by Kneubühler & Neubert, × 1.5.

This species has a rather short flagellum which is a bit shorter than the penis. MG are thin and fragile. The epiphallus goes over into the penial lumen without any penial papilla. Parallel but outside of the epiphallus is a penial appendix found. This penial appendix lies next to the epiphallus and is also covered by the penial sheath. It is blind on one side and opens into the penial lumen on the other side (PA in Fig. 5C, D). From there a huge penial papilla (PP) points towards the atrium. The PP is surrounded by massive muscles. In the atrium is a large atrial stimulator found and a smaller is located at the exit of the penis (PF).

Figure 5. 

Alabastrina alabastrites (NMBE 549817), Kebdana Mountain, Morocco; A shell B situs C penis D penial lumen; D = 21.91 mm, H = 13.36 mm, situs length 27.57 mm (atrium-flagellum). All photographs by Kneubühler, shell × 1.5.

Figure 6. 

Alabastrina alabastrites (NMBE 549812), cave Ifri n’Ammar, Morocco; A shell B situs C penis D penial lumen; D = 19.72 mm, H = 13.00 mm, situs length 26.27 mm (atrium-BCD). BC lost during dissection. All photographs by Kneubühler, shell × 1.5.

Figure 7. 

Alabastrina alabastrites (NMBE 549813), hills El Batel, Morocco; A shell B situs C penis; D = 17.25 mm, H = 10.85 mm, situs length 13.46 mm (atrium-flagellum). Situs is not complete. All photographs by Kneubühler, shell × 1.5.

Figure 8. 

Alabastrina alabastrites (NMBE 549816), Etsedda/ Kebdana, Morocco; A shell B situs C penis; D = 22.77 mm, H = 13.45 mm, situs length 36.84 mm (atrium-BCD). BC destroyed. All photographs by Kneubühler, shell × 1.5.

2018 Alabastrina tistutensis Galindo, Mostra mondiale, Cupra Marittima (2): 22–26.

Type specimen: Alabastrina tistutensis: holotype MMM Cupra Marittima (2): 23.

Specimens examined: for sequenced specimen, see Table 1.

Description. The shell is pale and characterised by a sharp keel. The aperture is white with a white lip. The mucus glands (MG) are fragile and slender. The flagellum is slightly shorter than the penis. The epiphallus is characterised by longitudinal tissue ridges and goes over into the penial lumen without any penial papilla. Parallel but outside of the epiphallus is a penial appendix found (PA in Fig. 9C). It is together with the epiphallus covered by the penial sheath. The PA is blind on one side and the other side opens into the penial lumen. This species possesses one penial papilla (PP in Fig. 9C) which is slightly smaller than in A. alabastrites but it is clearly visible. A large atrial stimulator is found in the atrium and a smaller stimulator is situated in front of the exit of the penis.

Figure 9. 

Alabastrina tistutensis (NMBE 555174), Tiztoutine, Morocco; A shell B situs C penis; D = 19.59 mm, H = 8.74 mm, situs length 13.51 mm (atrium-flagellum). Situs not complete. All photographs by Kneubühler, shell × 1.5.

1926 Siretia Pallary, Journal de Conchyliologie, 70: 19.

This genus is characterised by a triangular, toothless aperture, the short upper edge of the shell, its flat form, and by having four dark bands (Pallary 1926). Although Siretia has a peculiar shell morphology, Schileyko (2006) considers it as a subgenus of Alabastrina. Our phylogenetic analyses reveal it as a separate genus.

Figure 10

1909 Archelix pallaryi Kobelt, Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 41 (3): 134 [Taforalt im Gebiet der Beni Snassen].

1914 Archelix pallaryi, – Kobelt: in Rossmässler: Iconographie der Europäischen Land- & Süsswasser-Mollusken (2) 20: 21, fig. 2790.

1926 Siretia pallaryi, Journal de Conchyliologie, 70: 19, figs 5, 6, 8.

Type specimen: Siretia pallaryi: syntype SMF 75926.

Specimens examined: for sequenced specimen, see Table 1.

Description. In Figure 10B, a syntype of S. pallaryi from Teforalt (= Taforalt), Morocco (coll. CR Boettger ex Kobelt) is shown. The type specimen is slightly larger than our investigated specimen (Fig. 10A). Both show similar shell morphology and stripe pattern. Unfortunately, our specimen was badly preserved and a juvenile, therefore no proper investigation of the genital organs could be made.

Figure 10. 

A Siretia pallaryi (NMBE 549815), Kebdana Mountain, Morocco, D = 16.82 mm, H = 8.81 mm; B S. pallaryi (SMF 75926), Teforalt (= Taforalt), Morocco, coll. CR Boettger, D = 19.38 mm. All photographs by Kneubühler & Neubert, × 1.5.

Remarks. Holyoak and Holyoak (2017: 446) attribute this species to A Koch. However, in the description Kobelt explicitly mentions “Koch mss”. Therefore, Kobelt is considered the nomenclatural author of this taxon.

1817 Otala Schumacher, Essai d’un nouveau système des habitations des vers testacés: 58, 191 [type species Helix lactea OF Müller, 1774, by subsequent designation Pilsbry, 1895: 323].

1904 Otala (Dupotetia) Kobelt: in Rossmässler: Iconographie der Europäischen Land- & Süsswasser-Mollusken (2) 11: 158 [type species Helix dupotetiana Terver, 1839 by original designation].

1918 Alabastrina (Tingitana) Pallary, Bulletin de la Société d’ Histoire naturelle de l’Afrique du Nord, 9 (7): 145 [type species Archelix minettei Pallary, 1917 by monotypy].

This genus was recently revised by Holyoak and Holyoak (2017). After examining several hundreds of specimens from Morocco and Algeria, they distinguish five species within the genus Otala, i.e., O. punctata, O. lactea, O. xanthodon, O. tingitana (Paladilhe, 1875), and O. hieroglyphicula (Michaud, 1833). The species formerly attributed to Tingitana Pallary, 1918, and Dupotetia Kobelt, 1904 (genera which appeared to have species in the area of the Kebdana) are now lumped under Otala tingitana. This lumping approach is supported by the molecular study of Helicoidea by Razkin et al. (2015), who revealed that the genus Tingitana is nested within Otala. In our phylogenetic analysis we included a specimen of the well-known shell form “Tingitana minettei decussata”, which clustered within the O. xanthodon clade thus supporting the results of Razkin et al. (2015) and Holyoak and Holyoak (2017). More taxon sampling is needed to reveal the phylogenetic relationships within Otala.

Figs 11–16

Type specimens: Helix lucasii: MNHN IM-2000-31721.

Specimens examined: for sequenced specimens, see Table 1.

Description. The shell of O. lactea is characterized by a dark aperture. The shell diameter of the investigated specimens ranges between 27.01–40.81 mm and shell height between 15.77–21.75 mm. This species has a large and thick penial tube. It has two distinct penial papillae with each a large central pore. The distal penial lumen between the large tongue-shaped atrial stimulator and the distal penial papilla (PP2) exhibits longitudinal ridges. The distal penial papilla is located ca. 2 mm distally to the atrium. The penial chamber which is bordered by the two penial papillae ranges between 2–4 mm and is characterised by strong annular tissue folds. There is a short transformation zone between the proximal penial papilla (PP1) and the epiphallus. The epiphallus is characterised by longitudinal tissue ridges. The flagellum is ca. 1.5× the length of the penis. The BCD is ca. double in length as the BC, except for the specimen in Figure 13, where they are approximately the same length. The vagina is stout and short. The MG consist of two massive stems which subdivide into ten smaller branches.

Figure 11. 

Otala lactea (NMBE 553246), W Almocageme, Portugal; A shell B situs C penis and atrium; D = 29.82 mm, H = 18.71 mm, situs length 41.34 mm (atrium-BCD). All photographs by Kneubühler, shell × 1.5.

Figure 12. 

Otala lactea (NMBE 554174), N Málaga, Spain; A shell B situs; D = 27.25 mm, H = 18.60 mm, situs length 22.90 mm (atrium-albumin gland); juvenile, BC destroyed. All photographs by Kneubühler, shell × 1.5.

Figure 13. 

Otala lactea (NMBE 555171), Hassi Ouenzga/ Oriental, Morocco; A shell B situs C penis and atrium; D = 22.63 mm, H = 14.85 mm, situs length 34.60 mm (atrium-flagellum). All photographs by Kneubühler, shell × 1.5.

Figure 14. 

Otala lactea (NMBE 549951), W Aoulouz, Morocco; A shell B situs; D = 27.01 mm, H = 15.77 mm, situs length 30.77 mm (atrium-flagellum); juvenile; situs not complete; BC destroyed. All photographs by Kneubühler, shell × 1.5.

Remarks. The analysis includes also specimens of O. l. murcica (Fig. 15) from Almería, Spain, which is the type locality. This taxon is characterised by a larger shell and an aperture, which is enlarged and more reflected (Cadevall and Orozco 2016). The morphology of the genital organs shows no difference to the specimens of O. lactea investigated from Portugal or Morocco.

Figure 15. 

Otala lactea (NMBE 554175), W Almería, Spain; A shell B situs C penis and atrium; D = 31.89 mm, H = 18.23 mm, situs length 57.86 mm (atrium-BCD). All photographs by Kneubühler, shell × 1.5.

In a small area in north-eastern Morocco, another form of O. lactea occurs, namely Helix lucasii (Fig. 16D). Our investigation of a specimen from this population revealed some differences in the anatomy of the genital organs (Fig. 16C). The penial chamber is much longer than in the other specimens of O. lactea. The length of the penial chamber (PP1-PP2) is 4 mm and the length of the distal penial lumen (PP2-AS) is 1.8 mm. The internal structures differ substantially. Here, the inner walls of this tube are filled by numerous fine transverse ridges arranged in a very dense annular pattern. All other specimens seen so far displayed an irregular network of tissue folds in this section of the penis. Additionally the shell is quite large and flat with a comparatively strong basal tooth or strengthened lip.

Figure 16. 

Otala lactea (NMBE 545594); Etsedda/Kebdana, Morocco; A shell B situs C penis; D = 40.81 mm, H = 21.75 mm, situs length 61.47 mm (atrium-BCD), BC destroyed; D H. lucasii (syntype MNHN IM-2000-31721), Oran, Algeria, D = 35.4 mm. All photographs by Kneubühler & Neubert, shell original size.

Figs 17, 18

Specimens examined: for sequenced specimens, see Table 1.

Description. The shell is characterized by a white lip and a basal tooth. This species is characterized by a long and thick penial tube. It has a large penial papilla (PP), which is located ca. 2 mm distally to the atrium (Figs 17, 18) with a large central pore. The second proximal penial papilla is reduced and inconspicuous. The distal penial lumen between the atrial stimulator and the penial papilla exhibits a few low longitudinal ridges intersected by many small annular folds. The proximal lumen between penial papilla and epiphallus is filled by a network of irregularly shaped folds and small and large ridges. The epiphallus is characterised by longitudinal tissue ridges with a small transformation zone at the proximal end of the penial lumen. The flagellum has approximately the same length as the penis. The vagina is short and stout. The mucus glands (MG) consist of two massive stems which subdivide into 10–12 smaller subsequent branches. The BCD has approximately the same length as the BC. They are ca. 3× the length of the flagellum and the penis. The dominant structure in the atrium is a large, folded stimulator, which was also mentioned by De Mattia and Mascia (2011).

Figure 17. 

Otala punctata (NMBE 534228); Makouda, Algeria; A shell B situs C penis; D = 36.02 mm, H = 22.37 mm, situs length 59.77 mm (atrium-BCD). All photographs by Kneubühler, shell original size

Figure 18. 

Otala punctata (NMBE 554171); W Málaga, Spain; A shell B situs C penis; D = 30.30 mm, H = 18.05 mm, situs length 70.10 mm (atrium-BC). All photographs by Kneubühler, shell × 1.5.

Figs 19–23

Specimens examined: for sequenced specimens, see Table 1.

Description. The shell is characterized by a dark aperture with a white and strongly reverted lip. This species possesses one basal tooth. A palatal tooth is found in some specimens. The shell diameters of the investigated specimens range between 21.47–27.77 mm and shell height between 13.37–16.04 mm. Otala xanthodon has two distinct penial papillae with each a large central pore. The distal penial lumen between the atrial stimulator and the distal penial papilla (PP2) exhibits smooth longitudinal tissue ridges. The penial chamber which is bordered by the two penial papillae is filled by a network of irregularly shaped tissue folds and is ca. 3 mm long. There is a short transformation zone between the proximal penial papilla (PP1) and the epiphallus. The epiphallus contains few smooth longitudinal ridges. This species has a large flagellum which is ca. double the length of the penis. The BC is a thin tube and ca. half the length of the BCD. It has two massive mucus glands (MG) which subdivide in four thinner branches of which each again subdivides in two thin branches. The dominant structure in the atrium is a large tongue-shaped stimulator.

Figure 19. 

Otala xanthodon (NMBE 549825), Moulouya, Morocco; A shell B situs C atrium and penis; D = 23.13 mm, H = 14.49 mm, situs length 32.68 mm (atrium-BCD). BC destroyed. All photographs by Kneubühler, shell × 1.5.

Figure 20. 

Otala xanthodon (NMBE 549826), Moulouya, Morocco; A shell B situs C atrium and PP2 D penial chamber; D = 21.47 mm, H = 14.22 mm, situs length 37.23 mm (atrium-BCD). All photographs by Kneubühler, shell × 1.5.

Figure 21. 

Otala xanthodon (NMBE 549841), Kebdana Mountain, Morocco; A shell B situs; D = 26.85 mm, H = 15.74 mm, situs length 33.58 mm (atrium-flagellum). Situs not complete. All photographs by Kneubühler, shell × 1.5.

Figure 22. 

Otala xanthodon, Kebdana, Moulouya valley, Morocco; A shell from O. xanthodon (NMBE 555169), D = 22.33 mm, H = 13.61 mm; B shell from O. xanthodon (NMBE 555170), D = 23.10 mm, H = 13.37 mm. Kebdana, Djebel Sebaa Reyal/ Rif C shell from O. xanthodon (NMBE 549843), D = 27.77 mm, H = 16.04 mm. All photographs by Kneubühler, shell × 1.5.

Figure 23. 

Otala xanthodon (NMBE 549820), Guercif, Morocco; A shell B situs C atrium and penis; D = 26.74 mm, H = 15.96 mm, situs length 42.81 mm (atrium-BCD), BC destroyed; D Helix zaffarina Terver, 1839 (syntype MHNL 45001034), Oran, Algeria, coll. Michaud, D = 29.54 mm. All photographs by Kneubühler & Neubert, shell × 1.5.

Figs 24, 25

Specimens examined: Otala tingitana (NMBE 510549); for the sequenced specimen of “Tingitana minettei decussata” NMBE 549840, see Table 1.

Nomenclatorial note: The name “decussata Pallary” is a nomen nudum as already stated by Holyoak and Holyoak (2017: 463). Pallary never made the name available, nor did Llabador (1952). For the latter publication, the provisions of Article 13 ICZN (names published after 1930) rule that every new name must “be accompanied by a description or definition that states in words characters that are purported to differentiate the taxon” or Article 13.1.2. “be accompanied by a bibliographic reference to such a published statement”. No such statements are provided by Llabador. This taxon is well known and often treated as a subspecies of Tingitana minettei (Pallary, 1917) (see for example Cossignani 2014). The genus Tingitana Pallary, 1918 is synonymised with Otala by Holyoak and Holyoak (2017).

Description. The shells of “decussata” are flat and have a sharply keeled last whorl. The aperture is oval and dark brown inside with a white lip and a strong basal tooth. “Tingitana minettei decussata” has a network-like sculpture on its surface (Fig. 25). This is in contrast to Otala tingitana with a rather smooth surface and a few weakly developed radial ribs. In this species, the interior of the aperture is brighter and the basal tooth conspicuously smaller. Typically, O. xanthodon has a smooth shell with evenly rounded whorls and up to three apertural denticles.

Figure 24. 

Otala tingitana (NMBE 510549), Tarzout de Guigou, Morocco, D = 27.42 mm, H = 14.38 mm (specimens from the type locality of Archelix minettei Pallary, 1917). All photographs by Kneubühler, shell × 1.5.

Figure 25. 

“Tingitana minettei decussata” (NMBE 549840), Kebdana, Morocco; A shell B situs C atrium and penis; D = 32.45 mm, H = 16.12 mm, situs length 28.84 mm (atrium-flagellum). Situs not complete. All photographs by Kneubühler, shell × 1.5.

The genital organs of “decussata” are characterised by two distinct penial papillae, each with a central pore. The distal penial lumen between the atrial stimulator and the distal penial papilla (PP2) is characterised by a network of irregularly shaped folds with large and small ridges. The penial chamber exhibits many annular tissue folds and is ca. 3 mm long. Between the proximal penial papilla (PP1) and the epiphallus is a short transformation zone. The epiphallus is characterised by two strong and several smooth longitudinal ridges. The mucus glands consist of two massive stems which subdivide into several thinner branches which again become thinner in the second half. The dominant structure in the atrium is a large tongue-shaped stimulator. There are almost no differences in the inner and outer morphology of the genital organs of “decussata” and O. xanthodon specimens.

Remarks. According to field observations by R Hutterer, this particular taxon does only occur on top of one mountain in the Kebdana range; comparison with similar specimens illustrated by Cossignani (2014: 109) from Ras el Ma and Tazouta is pending. The distribution area of O. tingitana/minettei is far and separated by lowlands, so a position of this taxon as a species in its own right is highly probable. However, as long as topotypic specimens of O. tingitana are missing in the genetic analysis, the exact taxonomic position of “decussata Pallary” remains unclear. Our results signal a position within or close to O. xanthodon rather than to O. tingitana.