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Research Article
Systematics of the family Plectopylidae in Vietnam with additional information on Chinese taxa (Gastropoda, Pulmonata, Stylommatophora)
expand article infoBarna Páll-Gergely, András Hunyadi, Jonathan Ablett§, Hào Văn Lương|, Fred Naggs§, Takahiro Asami
† Shinshu University, Matsumoto, Japan
‡ Unaffiliated, Budapest, Hungary
§ Natural History Museum, London, United Kingdom
| Department of Construction and Forest Resource Development, Hoàng Liên National Park, Sa Pa Town, Vietnam
Open Access

Abstract

Vietnamese species from the family Plectopylidae are revised based on the type specimens of all known taxa, more than 600 historical non-type museum lots, and almost 200 newly-collected samples. Altogether more than 7000 specimens were investigated. The revision has revealed that species diversity of the Vietnamese Plectopylidae was previously overestimated. Overall, thirteen species names (anterides Gude, 1909, bavayi Gude, 1901, congesta Gude, 1898, fallax Gude, 1909, gouldingi Gude, 1909, hirsuta Möllendorff, 1901, jovia Mabille, 1887, moellendorffi Gude, 1901, persimilis Gude, 1901, pilsbryana Gude, 1901, soror Gude, 1908, tenuis Gude, 1901, verecunda Gude, 1909) were synonymised with other species. In addition to these, Gudeodiscus hemmeni sp. n. and G. messageri raheemi ssp. n. are described from north-western Vietnam. Sixteen species and two subspecies are recognized from Vietnam. The reproductive anatomy of eight taxa is described. Based on anatomical information, Halongella gen. n. is erected to include Plectopylis schlumbergeri and P. fruhstorferi. Additionally, the genus Gudeodiscus is subdivided into two subgenera (Gudeodiscus and Veludiscus subgen. n.) on the basis of the morphology of the reproductive anatomy and the radula. The Chinese G. phlyarius werneri Páll-Gergely, 2013 is moved to synonymy of G. phlyarius. A spermatophore was found in the organ situated next to the gametolytic sac in one specimen. This suggests that this organ in the Plectopylidae is a diverticulum. Statistically significant evidence is presented for the presence of calcareous hook-like granules inside the penis being associated with the absence of embryos in the uterus in four genera. This suggests that these probably play a role in mating periods before disappearing when embryos develop. Sicradiscus mansuyi is reported from China for the first time.

Keywords

Anatomy, revision, taxonomy, new species, Plectopylidae, Corillidae, mating behaviour, Vietnam, China

Introduction

At present, 477 species and subspecies in 22 families of terrestrial pulmonates are known from Vietnam (Schileyko 2011). As in other southeast Asian gastropods, most of these (77%) were described between 1880 and 1920 with poor locality data and based on shell characters only. Several species were described by examining only a single shell. Internal anatomy and exact collecting locality have been documented only for a few taxa. Accordingly, the systematics of most Vietnamese land snails remains questionable. Without accurate knowledge on their distribution and taxonomy, the recognition of possible threats and the subsequent establishment of appropriate conservation measures of these populations are impossible.

The Plectopylidae are currently the fifth largest pulmonate family in Vietnam with 28 species, after the Camaenidae s.l. (=Camaenidae and Bradybaenidae: 127 sp., 9 ssp.), Clausiliidae (84 sp., 10 ssp.), Ariophantidae (68 sp., 3 ssp.) and Streptaxidae (47 sp., 2 ssp.) (Schileyko 2011). The Plectopylidae are a group of medium sized (5–35 mm), usually flat, sinistral or dextral species, which have internal lamellae and plicae on both the palatal and parietal walls. This family is currently included within the Plectopyloidea together with the south Asian family Corillidae Pilsbry, 1905 and the south-west family African Sculptariidae Degner, 1923 (Bouchet and Rocroi 2005). However, Schileyko (1999) classified Sculptariidae in the superfamily Acavoidea. Plectopylidae differ from the probably closest group, which are the Corillidae with one or two vertical lamellae on the parietal wall. The mainly Sri Lankan Corillidae only have horizontal plicae. Plectopylidae have a wide distribution from northeastern India through the majority of southeast Asia to Peninsular Malaysia, northern Vietnam and southern Japan (Páll-Gergely and Hunyadi 2013 and references therein).

Morlet (schlumbergeri; 1886a, 1886b) was the first to describe a Vietnamese plectopylid species. Mabille (jovia and phlyaria; 1887a, 1887b), Ancey (villedaryi; 1888), Fischer (giardi and francoisi: 1898b, 1898a) and Möllendorff (choanomphala, emigrans, fruhstorferi, hirsuta: 1901) followed. Gude (1897b, 1899a, 1899b, 1899c, 1899d, 1900, 1901a, 1901b, 1901c, 1908, 1909) described new species, revised the taxa and published drawings of every species that had not been previously figured. He received most of the shell material from French collectors, mainly from Messager and Mansuy.

Gude (1899c) proposed the subgeneric division of Plectopylis (equivalent to the current Plectopylidae) by erecting seven “sections” (subgenera) within Plectopylis: Endothyra (replaced by Endothyrella by Zilch 1960), Chersaecia, Endoplon, Plectopylis, Sinicola, Enteroplax and Sykesia Gude, 1897a. The last two have been removed from the Plectopylidae; Enteroplax has been placed in the Strobilopsidae (Zilch 1959; Solem 1968; Schileyko 1998). Gude (1914) and Schileyko (2001) assigned Ruthvenia Gude, 1911 (nomen novum pro Sykesia) to the Endodontidae and Schileyko (2010) and Raheem et al. (2014) to the Charopidae. Gude’s (1899c) subdivision was primarily based on the morphology of palatal plicae, the direction of coiling and the depth of the umbilicus.

According to Gude (1899c), only the “section” Endoplon Gude, 1899 occurs in Vietnam. Gude also placed two Burmese (Myanmar) species (including the type species, Helix brachyplecta Benson, 1863) in Endoplon. Some Vietnamese species were subsequently placed in the subgenus Sinicola (Möllendorff 1901, Gude 1908). However, in some species descriptions Gude did not specify subgenera (Gude 1901a, 1908, 1909) or these were mentioned only within the text (Gude 1908). He mentioned Plectopylis tenuis as the connection between Sinicola and Endoplon (1908). Schileyko (1999) elevated Gude’s (1899c) “sections” (Endothyrella, Chersaecia, Endoplon, Plectopylis, Sinicola) to genera. Schileyko (1999) followed Yen (1939) and Zilch (1960) in placing the Chinese genus Amphicoelina Haas, 1933 within the Plectopylidae but Páll-Gergely and Asami (2014) classified Amphicoelina within the Camaenidae, as originally proposed by Haas (1933).

After Gude’s publications, virtually no taxonomic information was published on Vietnamese members of the family. Jaeckel (1950) reported two juvenile shells of “Plectopylis laminifera” from the debris of an unknown Tonkinese (northern Vietnamese) river. Páll-Gergely and Hunyadi (2013) concluded that juvenile shells of Sinicola jugatoria (Ancey, 1885) (synonym: laminifera) cannot be distinguished from congeners, that their distribution in China (northern Chongqing, eastern Hubei and Guizhou provinces) lies far from Vietnam, and that it probably does not occur within the country.

Revision of the Chinese Plectopylidae (Páll-Gergely and Hunyadi 2013) also revealed that the two recorded Burmese species of Endoplon show considerable differences from Vietnamese species. Vietnamese species have regularly ribbed embryonic whorls and no long horizontal parietal plicae, whereas the Burmese species possess a comparatively smooth protoconch and long horizontal parietal plica. Because the type species of Endoplon is one of the Burmese species, all the former Vietnamese Endoplon species were moved to a new genus, Gudeodiscus Páll-Gergely, 2013. The two Burmese Endoplon species are probably closely related to Plectopylis and Chersaecia species, which inhabit similar geographic regions (Myanmar, northern Thailand and north-eastern India) (Páll-Gergely and Hunyadi 2013).

The genus Sinicola Gude, 1899 (with the type species Helix fimbriosa von Martens, 1875) differs from Gudeodiscus mainly in the keeled body whorl (rounded in Gudeodiscus) and the presence of deciduous periostracal folds in most species (always absent in Gudeodiscus). Former Vietnamese Sinicola species (emigrans, fruhstorferi, soror and suprafilaris) were all classified within Gudeodiscus by Páll-Gergely and Hunyadi (2013). So far, Sinicola species have only been found to inhabit Chinese provinces (Chongqing, northern Guangxi, Guizhou, Hubei, Hunan and Sichuan). The third genus, Sicradiscus Páll-Gergely, 2013 (Type species. Plectopylis schistoptychia Möllendorff, 1886) was established for some small bodied species. Sicradiscus consists of two species groups. One has a rounded body whorl and a strong apertural fold: S. invius (Heude, 1885), feheri Páll-Gergely & Hunyadi, 2013, S. mansuyi (Gude, 1908) (only Vietnamese species of the genus) and S. securus (Heude, 1885). The other species group possesses a moderately shouldered body whorl and lacks an apertural fold: S. cutisculptus (Möllendorff, 1882), S. diptychia (Möllendorff, 1885), S. hirasei (Pilsbry, 1904), S. ishizakii (Kuroda, 1941) and S. schistoptychia. Sicradiscus transitus Páll-Gergely, 2013 with an apertural fold and a shouldered body whorl connects these two species groups. All Sicradiscus species differ from Sinicola by the presence of the anterior lamella. The rounded Sicradiscus differs from Gudeodiscus by the small size, strong apertural fold connected to the callus and the smooth ventral surface.

For the present revision of the Vietnamese Plectopylidae, we examined all the type specimens as well as many available non-type material deposited in public institutions. All samples deposited in HNHM, NHMSB, NHM, MNHN, NHMW, SMF and SNM were investigated. Some “problematic” samples were loaned and identified from RBINS and USNM. Material (usually with GPS data) obtained from the following private collections were investigated: András Hunyadi, Jozef Grego, Christa and Jens Hemmen, Kenji Ohara, Jamen Uiriamu Otani and Wim Maassen. Altogether approximately two hundred samples with exact locality data were examined. Fischer and Dautzenberg (1904) mentioned two names (Plectopylis anoplon and simulans) from Vietnam but presented no formal descriptions. Although listed by Thanh (2008), these nomen nuda cannot be assigned to species. Gude’s material is deposited in NHM, and most samples from Lieutenant Colonel Messager are housed in MNHN. Messager probably sent only a few shells to Gude, who published on these in 1909. The six species described by Gude (1909) are problematic. Investigation of these specimens including Messager’s original material allowed us to gain a better understanding of species boundaries based on morphological gaps in continuously varying shell characters.

Here we present the outcome of systematic revision of Vietnamese Plectopylidae (see summary in Table 1) with reproductive anatomy and radula morphology of eight species. Additionally, we publish information on the radula of fifteen Chinese species. The genus Gudeodiscus is divided into two subgenera based on anatomical and radula information of Chinese and Vietnamese species.

(Sub)generic division of Vietnamese Plectopylidae in Gude’s (1899c) revision, in the original description (in case of species described after Gude 1899c), and in this study. Synonymies are also indicated. Valid taxa with bold italic.

(sub)species section in Gude 1899c (sub)genus in the original publication This study synonym of
anceyi Gude, 1901 not specified Gudeodiscus (Gudeodiscus?)
anterides Gude, 1909 not specified phlyarius
bavayi Gude, 1901 not specified francoisi
choanomphala Möllendorff, 1901 Endoplon villedaryi
congesta Gude, 1899 Endoplon giardi
cyrtochila Gude, 1909 not specified Gudeodiscus (Gudeodiscus?)
dautzenbergi Gude, 1901 not specified Gudeodiscus (Gudeodiscus)
emigrans Möllendorff, 1901 Sinicola Gudeodiscus (Veludiscus)
fallax Gude, 1909 not specified phlyarius
fischeri Gude, 1901 not specified Gudeodiscus (Gudeodiscus)
francoisi Fischer, 1898 Endoplon Gudeodiscus (Gudeodiscus?)
fruhstorferi Möllendorff, 1901 Sinicola Halongella
giardi Fischer, 1898 Endoplon Gudeodiscus (Gudeodiscus)
gouldingi Gude, 1909 not specified phlyarius
hirsuta Möllendorff, 1901 Endoplon schlumbergeri
infralevis Gude, 1908 not specified Gudeodiscus (Gudeodiscus?)
jovia Mabille, 1887 Endoplon schlumbergeri
lepida Gude, 1900 not specified francoisi
mansuyi Gude, 1908 not specified Sicradiscus
messageri Gude, 1909 not specified Gudeodiscus (Gudeodiscus)
moellendorffi Gude, 1901 Endoplon phlyarius
persimilis Gude, 1901 not specified dautzenbergi
phlyarius Mabille, 1887 Endoplon Gudeodiscus (Gudeodiscus)
pilsbryana Gude, 1901 (new name for villedaryi) not specified schlumbergeri
quadrilamellatus Páll-Gergely, 2013 Gudeodiscus Gudeodiscus (Veludiscus)
schlumbergeri Morlet, 1886 Endoplon Halongella
soror Gude, 1908 Sinicola infralevis
suprafilaris Gude, 1908 Sinicola Gudeodiscus (Gudeodiscus?)
tenuis Gude, 1901 not specified fischeri
verecunda Gude, 1909 not specified phlyarius
villedaryi Ancey, 1888 Endoplon Gudeodiscus (Gudeodiscus)

Materials and methods

Shell whorls (exactness 0.25) were counted according to Kerney and Cameron (1979: 13). Differences in size are indicated in the diagnosis using the following terms: very small (6–10 mm), small (10–15 mm), medium-sized (15–20 mm), large (20–25 mm), very large (25–30 mm).

The palatal plicae can be observed from the interior and exterior view. This is indicated in the figure captions in all cases. If enough shell material was available, a shell fragment with the palatal plicae was broken out and the lamellae were observed directly (interior view). If shell material was limited, the plicae are figured as they were visible through the shell wall (external view). For nomenclature of lamellae (vertical parietal folds) and plicae (horizontal parietal folds and palatal folds) see Figure 1.

Figure 1.

Nomenclature of parietal (A) and palatal (B) plicae and lamellae. Small arrows under the letters show the direction of the aperture. Large arrow next to figure B shows the direction of counting of palatal plicae (first above, last below). Abbreviations: al: anterior lamella; lp: lower plica; pl: posterior lamella; up: upper plica.

Examined specimens for each taxon are separately listed as types, museum material and new material. Most specimens in the last category are geo-referenced whereas precise localities are unknown for the majority of older museum material. The original code of locality is indicated before the locality of newly collected material. Certain populations are referred to by using these codes, and the inventory numbers in case of museum material, for example in the measurements and species remarks. In the distribution maps, localities which are closer to each other than 2 km were indicated with a single plot to make the map easier to understand. Chinese localities published by Páll-Gergely and Hunyadi (2013) are also indicated on the maps. The distances between parapatric populations (Table 2) were measured using Google Earth.

Co-occurrence of Vietnamese Plectopylidae. Three stars indicate co-occurrence observed with newly-collected materials, which were collected by the same collector in each strict sympatry. Two stars indicate that the two species were collected at geographically close sites by the same or different collectors (anceyi-fischeri: 940 m; dautzenbergi-cf. phlyarius: 1160 m; anceyi-suprafilaris: 2340 m; fischeri-emigrans quadrilamellatus: 4650 m; francoisi-phlyarius: 85 m; francoisi-suprafilaris: 290 m; giardi-phlyarius: 350 m; phlyarius-suprafilaris: 370 m; phlyarius-mansuyi: 350 m). One star indicates frequent presence of the two species mixed within museum samples.

anceyi fischeri francoisi giardi phlyarius (gouldingi/fallax) phlyarius hemmeni sp. n. mansuyi
cyrtochilus ***
dautzenbergi **
fischeri **
francoisi ***
giardi *** *** ***
messageri *
messageri raheemi ssp. n. *** ***
phlyarius *** ** ** **
emigrans quadrilamellatus *** **
suprafilaris ** ** *** ** ***
villedaryi *** ***

Ethanol-preserved specimens were dissected under a Leica stereomicroscope, with camera attached to provide photographs of the genital structure from which drawings were produced. In description of the reproductive system, we used the terms “distal” and “proximal” in relation to the genital atrium. At dissection of each specimen, we recorded whether embryos are present in the uterus and calcareous granules on the internal surface of penis (Table 3). Fisher’s exact test was used to examine the association of the presence of embryo and the absence of granules by treating all the examined individuals as replicates across the four genera because of limited sample sizes in each genus (Tables 45).

Association between the presence of calcareous granules in the penis and embryos in the uterus in the genera of “Eastern Plectopylidae”. Source of information: 1: this study, 2: Páll-Gergely and Hunyadi (2013), 3: Páll-Gergely and Asami (2014).

Name source Country, province elevation (m) date embryos shape of granules No. of specimens Notes
G. emigrans otanii 3 China, Guangxi 180 November 13 present no granules 2 the third specimen was aphallic
G. eroessi eroessi 3 China, Guangxi 153 November 9 present no granules 2
G. fischeri 1 Vietnam, Tuyên Quang 70 March 19 absent hook-like 1
G. fischeri 1 Vietnam, Bắc Kạn 335 November 19 present no granules 1
G. giardi giardi 1 Vietnam, Cao Bằng 430 November 16 absent hook-like 1
G. giardi giardi 3 China, Guangxi 308 January 10 absent flat, oval 1
G. messageri raheemi 1 Vietnam, Hòa Bình 1120 October 15 present no granules 1
G. multispira 2 China, Guangxi 160 October 14 present no granules 3
G. multispira 3 China, Guangxi 252 November 12 present no granules 1
G. okuboi, specimen1 3 China, Guangxi 131 November 9 present no granules 1
G. okuboi, specimen2 3 China, Guangxi 131 November 9 absent no granules 1
G. phlyarius 1 Vietnam, Lạng Sơn 370 April 1 present no granules 1
G. phlyarius 2 China, Guangxi 190 October 11 absent hook-like 1
G. phlyarius 2 China, Guangxi 360 October 23 present no granules 1
G. phlyarius (“fallax”) 1 Vietnam, Lào Cai 270 October 4 absent flat, oval 2
G. pulvinaris pulvinaris 3 Hong Kong 300-500 June absent hook-like 1
G. pulvinaris robustus 2 China, Guangxi 140 October 17 present no granules 1
G. villedaryi 1 Vietnam, Thái Nguyên 365 May 20 present no granules 1
G. villedaryi 1 Vietnam, Thái Nguyên 365 November 12 absent hook-like 1
H. fruhstorferi 1 Vietnam, Quảng Ninh 20 August 14 present very thin, flat, no particular shape 1
H. schlumbergeri 1 Vietnam, Hải Phòng 20 April 4 present flat, thin, with no particular shape 1
Sch. schlumbergeri 1 Vietnam, Hải Phòng 30 November 22 absent flat, thin, with no particular shape, or T-shaped 1
Sic. invius 3 China, Sichuan 1087 September 17 absent no granules 2
Sic. mansuyi 1 Vietnam, Cao Bằng 570 May 28 present no granules 2 subadult
Sic. schistoptychia 2,3 China, Hunan 450 November 11 present tiny flat rounded granules 1
Sic. transitus 3 China, Guangxi 650 September 12 absent minute, flat, rounded 1 subadult
Sin. asamiana 3 China, Sichuan 860 September 16 present no granules 1
Sin. emoriens 2,3 China, Guangxi 125 November 8 present no granules 2
Sin. fimbriosa 2 China, Hunan 590 October 20 absent no granules 1 subadult
Sin. murata 3 China, Sichuan 860 September 16 present no granules 1
Sin. murata 3 China, Sichuan 1090 September 17 present no granules 1
Sin. reserata azona 3 China, Guizhou 863 May 10 present no granules 1
Sin. stenochila 3 China, Hubei 220 November 3 absent globular or elongated 2

Association of the presence of embryo and the absence of granules within the genus Gudeodiscus.

embryo Probability
present absent
granule present 0 7 0.0001
absent 12 1

Association of the presence of embryo and the absence of granules within all four genera (Gudeodiscus, Halongella gen. n., Sicradiscus, Sinicola).

embryo Probability
present absent
granule present 3 10 0.0006
absent 18 3

To demonstrate the continuous variation of shell heights and diameters across Plectopylis anterides/gouldingi, P. fallax, and P. fallax var. major specimens (synonyms of Gudeodiscus phlyarius; Figure 16), we randomly selected a few samples which can be assigned to those taxa.

The buccal mass was removed and soaked in 2 molar KOH solution for 5 hours before extracting the radula, which was preserved in 70% ethanol. Radulae were directly observed without coating under a low vacuum SEM (Miniscope TM-1000, Hitachi High-Technologies, Tokyo).

Taxonomic treatment

This revision is based on morphology by examination of specimens and literature. Thus the present taxa are defined based on their morphological differences. The present species are hypothesized as species defined by the biological species concept (Mayr 1942), although evidence for differences in sympatry was not always available within the relevant species group. Table 2 shows sympatric species pairs. No specimens were found that show transitional characters between sympatric species. This suggests that these are biological species reproductively isolated from each other.

Previously recognized taxa are synonymized when their differences between traditionally recognized species (often present as only a few individuals) are considered to be very minor. Sometimes, these differences (mainly in the morphology of the plicae and lamellae) show a geographical pattern. If these minor differences fall within the range of the species’ morphological diversity, the taxa are synonymized.

Abbreviations

HA Collection András Hunyadi (Budapest, Hungary);

HE Collection Hemmen (Wiesbaden, Germany);

HNHM Magyar Természettudományi Múzeum (Budapest, Hungary);

JG Collection Jozef Grego (Banská Bystrica, Slovakia);

NHMSB Natural History Museum, Sibiu (Romania), Bielz collection;

NHM & NHMUK Natural History Museum, London;

MNHN Muséum National d’Histoire Naturelle (Paris, France);

NHMW Naturhistorisches Museum Wien (Vienna, Austria);

OK Collection Kenji Ohara, Nishinomiya Shell Museum (Nishinomiya, Japan);

PGB Collection Barna Páll-Gergely (Mosonmagyaróvár, Hungary);

RBINS Royal Belgian Institute of Natural Sciences (Brussels, Belgium);

SMF Senckenberg Forschungsinstitut und Naturmuseum (Frankfurt am Main, Germany);

USNM Smithsonian National Museum of Natural History (Washington, USA);

VA Collection András Varga (Gyöngyöshalász, Hungary);

WM Collection Wim J. M. Maassen (Echt, The Netherlands);

ZMUC Zoological Museum, University of Copenhagen (Denmark);

coll collection of

jb juvenile/broken shells

leg collected by

ex from the collection of

D shell diameter

H shell height

Results

Radula information

Information on the radula morphology of Chinese Plectopylidae species has never been published. To provide a comprehensive basis of the radula morphology of Vietnamese species, we publish images of the radula of some Chinese species as well. The key characters of the radula (size of the central tooth in relation to the ectocone of the first lateral, the shape of the mesocone of the first lateral and the morphology of the marginals) are compiled in Table 6.

Key characters of the radula of Chinese and Vietnamese Plectopylidae species. Abbreviations: L lateral M marginal.

taxon L M size of central shape of the first lateral morphology of the marginals
G. (V.) emigrans otanii 9 11 slightly smaller than the ectocone of the first lateral rhomboid, rather blunt bicuspid or tricuspid with blunt inner cusp and shallow incision between the inner two cusps
G. (V.) eroessi 10 10 smaller than the ectocone of the first lateral rhomboid, rather blunt bicuspid or tricuspid with blunt inner cusp and shallow incision between the inner two cusps
G. (V.) okuboi 7 13 slightly smaller than the ectocone of the first lateral rhomboid, rather blunt tricuspid with blunt inner cusp and shallow incision between the inner two cusps
G. (V.) pulvinaris pulvinaris 7 14 smaller than the ectocone of the first lateral rhomboid, rather blunt tricuspid with blunt inner cusp and shallow incision between the inner two cusps
G. (G.) fischeri 9 13 as large as or larger than the ectocone of the first lateral rhomboid, pointed tricuspid, inner two rather blunt, incision between them deep
G. (G.) giardi 12 15 as large as the ectocone of the first lateral rhomboid, pointed bicuspid or tricuspid with blunt inner cusp and shallow incision between the inner two cusps
G. (G.) messageri raheemi 8 16 as large as or larger than the ectocone of the first lateral rhomboid, pointed tricuspid with rather sharp inner cusp and deep incision between the cusps
G. (G.) multispira 9 14 as large as or larger than the ectocone of the first lateral slender oval tricuspid with rather blunt inner cusp and deep incision between the cusps
G. (G.) phlyarius 9 12 as large as the ectocone of the first lateral rhomboid, pointed bicuspid or tricuspid with blunt inner cusp and shallow incision between the inner two cusps
G. (G.) villedaryi 9 10 as large as or slightly smaller than the ectocone of the first lateral rhomboid, pointed bicuspid or tricuspid with blunt inner cusp and shallow incision between the inner two cusps
H. fruhstorferi 8 12 much smaller than the ectocone of the first lateral slender rhomboid mostly bicuspid, some of them tricuspid with blunt inner cusps
H. schlumbergeri 10 14 smaller than the ectocone of the first lateral oval bicuspid or tricuspid with blunt inner cusp and shallow incision between the inner two cusps
Sic. invius 7 8 as large as or larger than the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sic. mansuyi 8 10 as large as the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them, some of them quadricuspid
Sic. schistoptychia 6 14 as large as or larger than the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sic. transitus 6 10 as large as the ectocone of the first lateral triangular tricuspid with pointed cusps and deep incision between them
Sin. asamiana 8 11 as large or almost as large as the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sin. emoriens 6 14 as large as or larger than the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sin. fimbriosa 10 15 larger than the ectocone of the first lateral slender with concave inner line tricuspid with pointed cusps and deep incision between them
Sin. jugatoria 9 12 as large as the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sin. murata 8 12 as large as the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sin. reserata azona 11 14 as large as the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them
Sin. stenochila 8 13 as large as the ectocone of the first lateral slender with parallel, straight margins and pointed end tricuspid with pointed cusps and deep incision between them

The overall morphology of the radula was similar in all species. The lateral teeth are arranged along straight rows, whereas the marginals stand in oblique rows. The distinction between the last laterals and the first marginals is not easy, especially in those specimens in which their morphology (bi- or tricuspid) does not differ. Therefore, the data on the number of laterals and marginals are only guidelines.

Systematic treatment
Family Plectopylidae Möllendorff, 1898

Gudeodiscus Páll-Gergely, 2013

2013 Gudeodiscus Páll-Gergely in Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 4, 8.

Type species

Plectopylis phlyaria Mabille, 1887, by original designation.

Included taxa

Subgenus Gudeodiscus and subgenus Veludiscus subgen. n.

Diagnosis

Shell rarely small, usually middle sized or large, dextral, body whorl rounded, without periostracal folds on the “upper keel” of the whorls. The whole protoconch is usually very finely, regularly ribbed (see Figure 10A). The only known exceptions are Gudeodiscus villedaryi (see Figure 10B) and G. dautzenbergi. Teleoconch usually has a reticulated sculpture; more prominent on the dorsal side; sometimes with very small periostracal filaments, but these are always arranged radially, never in spiral lines. A short apertural fold is present in the majority of the species. Palatal plicae usually 6, sometimes 5 or 7, they are usually free, very rarely connected by a ridge. Middle palatal plicae can be horizontal, oblique or almost vertical, they are usually depressed “Z” or “V”-shaped. The first plica is always straight and parallel with the suture, the last is slightly curved or oblique. On the parietal wall there are two vertical lamellae or the anterior one is missing or dissolved into small denticles or parallel horizontal plicae. Usually horizontal plicae are visible above and below the anterior lamella, near the sutures.

Penial caecum usually present (very rarely absent). Penis internally with longitudinal folds; the middle or proximal portion of the penis can have transverse or reticulated sculpture; the longitudinal folds are thickened on the apical part of the penis and form “pockets”, each of which holds a calcareous, usually hook- or claw-like translucent granule; these granules are probably present seasonally when the snails are reproductively active and disappear when embryos develop in the uterus; the pockets stand in one row or rarely in two rows on the opened penis wall. Epiphallus with simple internal longitudinal folds.

Differential diagnosis

The body whorl of the species belonging to Sinicola is keeled or shouldered, often with flat, deciduous periostracal folds arranged in one row on the keel. In contrast, all Gudeodiscus species have rounded body whorl and never have periostracal folds arranged in a spiral line. Moreover, in Sinicola there are no “pockets” on the inner wall of the penis. The shells of Halongella gen. n. are indistinguishable from those of Gudeodiscus. Halongella gen. n. species have parallel, longitudinal folds on the inner wall of the penis with tiny, flat calcareous granules between the folds, all along the penis; there are no determined “pockets” for the granules at the apical part of the penis, which are so characteristic for Gudeodiscus. Additionally, the longitudinal folds inside the epiphallus of Halongella gen. n. species have characteristic transverse projections which overlap with those of neighbouring folds. In contrast, Gudeodiscus species have parallel folds on the inner wall of the epiphallus. Additionally, most anatomically examined Gudeodiscus specimens had a penial caecum, which is missing in both Halongella gen. n. species. See also under Sicradiscus.

Gudeodiscus Páll-Gergely, 2013

Diagnosis

Shell indistinguishable from Gudeodiscus (Veludiscus) subgen. n. Anatomy: The epiphallus has a somewhat thickened proximal part; retractor muscle simple, inserts on the distal end of the penial caecum, or if it is missing, than on the distal end of the penis (at the penis-epiphallus transition). Radula: central tooth usually as large as or slightly larger than the ectocone of the first lateral; mesocone of the first lateral is moderately wide, in most cases has parallel edges. Marginals usually tricuspid with rather pointed inner cusp and rather deep incision between the inner two cusps.

Included taxa

anceyi (Gude, 1901)(?), concavus Páll-Gergely, 2013(?), cyrtochilus (Gude, 1909)(?), dautzenbergi (Gude, 1901), fischeri (Gude, 1901), francoisi (Fischer, 1899)(?), giardi (Fischer, 1898), hemmeni Páll-Gergely & Hunyadi, sp. n.(?), infralevis (Gude, 1908)(?), marmoreus Páll-Gergely, 2014(?), messageri (Gude, 1909), multispira (Möllendorff, 1883), phlyarius (Mabille, 1887), soosi Páll-Gergely, 2013(?), suprafilaris (Gude, 1908)(?), ursula Páll-Gergely & Hunyadi, 2013(?), villedaryi (Ancey, 1888), yanghaoi Páll-Gergely & Hunyadi, 2013(?), yunnanensis Páll-Gergely, 2013(?).

Remarks

All known Gudeodiscus species remain in this subgenus with the exception of G. goliath Páll-Gergely & Hunyadi, 2013 because of its similar shell and distribution area to G. pulvinaris robustus Páll-Gergely & Hunyadi, 2013 and G. emigrans otanii Páll-Gergely & Hunyadi, 2013. Those with unknown anatomy and radula morphology have questionable subgeneric assessment. The shell of G. dautzenbergi is very similar to the nearby occurring G. villedaryi, therefore we think there is no need to question the subgeneric status.

Gudeodiscus (Gudeodiscus?) anceyi (Gude, 1901)

Figures 2B, 9G, 11C–F

1901a Plectopylis Anceyi Gude, Journal de Conchyliologie, 49: 208–209., Figs 6a–e, Plate 6, Figs 6a–c. [“Bac-Kan (le type); secteur de Nac-Ri; entre Cho-Moi et That-Khé”]

2013 Gudeodiscus anceyi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Tonkin, Bac-Kan, leg. Messager, MNHN 24600 (syntype, Figure 2B); Tonkin, Bac-Khan, NHMW 50858 (2 syntypes).

Museum material examined

Tonkin, coll. Jetschin ex Berlier 1908, SMF 118124/2; Tonkin, Bac-Khan, coll. Jaeckel, S. H. ex Rolle, SMF 207668/1; Tonkin, Bac-Khan, coll. Dosch ex Rolle, SMF 172078/4; Tonkin, Than-Moi, probably ex Messager, SMF 150135/1; Central-Tonkin, Chiam-Hoa, coll. Möllendorff ex Fruhstorfer SMF 150134/1; Tonkin, Bac-Kan, leg. Messager, 22.11.1898, RBINS/5; Secteur de Nac-Ri, RBINS/1; Secteur de Nac-Ri, leg. Messager (n. 33), RBINS/1; Tonkin, entre Cho-Moi, et That-Khé, leg. Messager (n. 33), RBINS/11; Tonkin, Bac-Kan, RBINS/4; Muong-Kong, leg. Messager, MNHN-IM-2012-2139/1; Secteur de Nac-Ri, Bac-Kan, leg. Messager, MNHN-IM-2012-2250/343; Bac-Kan, leg. Messager, MNHN-IM-2012-2252/60; Bac-Kan, leg. Messager, MNHN-IM-2012-2258/38; That-Khé, coll. Mansuy, MNHN-IM-2012-2259/12; Cho-Moi, leg. Messager, MNHN-IM-2012-2263/48; Bac-Kan, leg. Messager, MNHN-IM-2012-2265/30; Long-Phai, leg. Messager, MNHN-IM-2012-2270/36; Cho-Moi, leg. Messager, MNHN-IM-2012-2275/30; Long-Phai, leg. Messager, MNHN-IM-2012-2277/26; Cho-Moi, leg. Messager, MNHN-IM-2012-2283/95; Cao-Bang, leg. Messager, MNHN-IM-2012-2468/1; Na-Ri, leg. Messager, MNHN-IM-2012-2285/40; Long- Phai, leg. Messager, MNHN-IM-2012-2286/36; Bac-Kan, coll. Letellier, 1949, MNHN-IM-2012-2287/1; Cho-Moi, leg. Messager, MNHN-IM-2012-2300/25; Bac-Kan, coll. Lavezzari, 1929, MNHN-IM-2012-2301/15; Bac-Kan, leg. Messager, MNHN-IM-2012-2305/62; Long-Phai, leg. Messager, MNHN-IM-2012-2312/30; Bac-Kan, coll. Staadt, 1969, MNHN-IM-2012-2313/4; Na-Ri, leg. Messager, MNHN-IM-2012-2376/34; Pakhé, leg. Messager, MNHN-IM-2012-2453/1; Tonkin, Bac-Khan, coll. Rolle, 4/11/08, NHMUK 20130585/3; Tonkin, Bac-Khan, coll. Rolle, 4/11/08, NHMUK 20130586/3; Tonkin, Bac-Kan, 13/6/01, NHMUK 20130587/3; Tonkin, Bac-Kan, coll. Rolle, 4/11/08, NHMUK 20130588/3; Tonkin, 4/11/8, NHMUK 20130589/2; Tonkin, Bac-Kan, coll. Salisbury ex Beddome, NHMUK 20130590/2; Tonkin, coll. Lucas, NHMUK 20130591/2; Tonkin, Bac-Khan, NHMUK 1916.03.16.1–2/2; Tonkin, NHMUK 1901.08.01.22/1; Tonkin, NHMUK 1901.7.11.89–90/2; Tonkin, Bac-Kan, coll. Rušnov ex Rolle ex Messager, NHMW 92556/6; Tonkin, Bac-Kan, coll. Wagner ex Messager, NHMW 92557/2; Tonkin, Cho-Moi, coll. Oberwimmer ex. Rosen, NHMW 71640/O/9480/1; Tonkin, Ngam-Son, coll. Wagner ex Messager, NHMW 82558/2; Tonkin, Cho-Moi, coll. Rosen, NHMW 71640/O/9479/2; Tonkin, Bac-Khan, coll. Rolle ex Messager, NHMW 50858/2; Tonkin, That-Khé, entre Cho-Moi, coll. Steenberg, ZMUC-GAS-1809/2.

New material examined

Vn10-33B Bắc Kạn Province, Ba Bể Nat. Park, surroundings of Na Phoong cave, GPS not recorded, leg. Hemmen, Ch. & J., 10.10.2010., PGB/1; GS21 Bắc Kạn Prov, Na Rì District, left side of road from Kim Hỷ to Bắc Kạn, 2 km after Kim Hỷ, in leaf litter bellow high limestone walls above road, 583 m, 22°16.861'N, 106°2.169'E, leg. Grego, J. & Śteffek, J., 06.04.2012., JG/1; GS22 Bắc Kạn Prov, Na Rì District, 2 km S of Bản Dền (=Dền Village), limestone rocks at side of the valley near gold quarry, in small cavern in dense rain forest, ca 590 m, 22°14.547'N, 106°0.527'E, leg. Grego, J. & Śteffek, J., 06.04.2012., JG/1, PGB/1; GS24 Bắc Kạn Prov, Na Rì District, 2 km S of Bản Dền, W slopes of a deep sinkhole covered with forest, leaf litter under high limestone wall, ca 640 m, 22°14.506'N, 106°0.521'E, leg. Grego, J. & Śteffek, J., 06.04.2012., JG/1; 2011/82 Lạng Sơn Province, Lũng Phầy Pass, Thất Khê N 13 km, 475 m, 22°20.363'N, 106°27.098'E, leg. Hunyadi, A., 15.11.2011., HA/4; 2011/91 Bắc Kạn Province, Ba Bể Nat. Park, 500 m on the path starting from the bungalows, 240 m, 22°25.072'N, 105°37.941'E, leg. Hunyadi, A., 17.11.2011., HA/3; 2011/93 Bắc Kạn Province, Ba Bể Nat. Park, Đầu Đằng Waterfall, above the waterfall, 175 m, 22°27.159'N, 105°34.193'E, leg. Hunyadi, A., 18.11.2011., HA/1; 2011/94 Bắc Kạn Province, Ba Bể Nat. Park, Ao Tiên, near the lake, 155 m, 22°26.831'N, 105°37.023'E, leg. Hunyadi, A., 18.11.2011., HA/3+1jb; 2011/96 Bắc Kạn Province, Ba Bể Nat. Park, Thẳm Kịt Cave 2 km, look-out tower, 335 m, 22°24.686'N, 105°37.710', leg. Hunyadi, A., 19.11.2011., HA/1; 2011/100 Bắc Kạn Province, Ba Bể Nat. Park, Bố Lù, 600 m from the harbour towards Pắc Ngòi, right side of the road, 175 m, 22°23.989'N, 105°37.523'E, leg. Hunyadi, A., 19.11.2011., HA/3; 2011/101 Bắc Kạn Province, Ba Bể Nat. Park, Na Phoong Cave, south of Bố Lù, 215 m, 22°23.341'N, 105°36.812'E, leg. Hunyadi, A., 19.11.2011., HA/3; 2012/45 Bắc Kạn Province, Na Rì Distr., Kim Hỷ SSE, 1.5 km on a by-road from the road nr. 279, 420 m, 22°16.988'N, 106°02.990'E, leg. Hunyadi, A., 29.05.2012., HA/3; Vn10-68 Cao Bằng Province, right off old rd., ca. 33 km from Cao Bằng to Đông Khê, 22°27.547'N, 106°22.331'E, leg. Hemmen, Ch. & J., 26.03.2010., HE/1; Vn11-159 Lạng Sơn Province, at km 74.8 on road 1B, Đồng Đăng to Thái Nguyên (8 km S Bắc Sơn), 21°54.543'N, 106°17.298'E, leg. Hemmen, Ch. & J., 02.04.2011., HE/7; Vn11-31C Bắc Kạn Province, Ba Bể Nat. Park, near Puổng Cave, 22°27.835'N, 105°38.997'E, leg. Hemmen, Ch. & J., 17.03.2011., HE/1; same data, leg. Hemmen, Ch. & J., 19.10.2009., PGB/2.

Diagnosis

Shell very small, finely ribbed, whole shell with easily-visible spiral lines, spire elevated, umbilicus deep; aperture with well-developed, long apertural fold (Figure 9G). Parietal wall with two lamellae, the anterior is fused with the lower plica, upper plica missing (or short and fused to the anterior lamella); palatal plicae oblique, short, sometimes connected with a ridge (Figures 11C–F).

Measurements

(in mm): D = 7.4–7.9, D: 3.5–4 (shells from different localities, n=3); D = 9.2–9.8, H = 4.5–4.6 (Vn11-31C).

Differential diagnosis

Gudeodiscus messageri is larger than G. anceyi and lacks the apertural fold and spiral lines on the ventral surface of the shell. Gudeodiscus anceyi is smaller than typical G. phlyarius, has stronger spiral lines, and has no horizontal plica under the lamellae, which are present in most populations assigned to G. phlyarius. The G. phlyarius populations living near the Chinese border (typical anterides, gouldingi, fallax, verecunda) are usually larger than G. anceyi and they often lack the apertural fold and the spiral lines on the ventral side of the shell. For differences with G. hemmeni sp. n. and Sicradiscus mansuyi, see under those species.

Intraspecific diversity

Relatively low; shell characters, namely the size and general shell and aperture shape are rather stable. The morphology of the palatal plicae shows some diversity. The species is easily recognisable and can be separated from other plectopylid species without major problems.

Distribution

(see Figure 40): We have newly-collected material only from Bắc Kạn Province. The species was previously recorded from That Khé (Lạng Sơn Province) and Nac Ri (Hà Giang Province) (Gude 1901a, see also Figure 39).

Gudeodiscus (Gudeodiscus?) cyrtochilus (Gude, 1909)

Figures 2F, 15E–G

1909 Plectopylis cyrtochila Gude, Proceedings of the Malacological Society of London, 8: 217–218., Plate 9, Figs 5, 5a–b. [“Muong-Kong”].

2013 Gudeodiscus cyrtochilus, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 11–12., Figs 17, 41, 75 (map).

Types examined

Tonkin, Muong-Kong, leg. Messager, NHMUK 1922.8.29.59 (syntype, Figure 2F).

Museum material examined

Muong-Kong, coll. Denis 1946, MNHN-IM-2012-2249/3; Muong-Kong, leg. Messager, MNHN-IM-2012-2251/14.

New material examined

2012/46 Hà Giang Province, Hà Giang 105.2 km towards Ðồng Văn, Vân Chải Commune, right side of the road nr. 4C, 23°08.865'N, 105°10.789'E, leg. Hunyadi, A., 31.05.2012., HA/7+4 jb; 2012/47 Hà Giang Province, Hà Giang 105.5 km towards Ðồng Văn, Vân Chải Commune, left side of the road 4C, 23°09.084'N, 105°10.774'E, leg. Hunyadi, A., 31.05.2012., HA/19+10jb, PGB/3; 2012/49 Hà Giang Province, Hà Giang 149.4 km towards Mèo Vạc, about 5 km SE from Ðồng Văn, right side of the road 4C, ca 1090 m, 23°15.528'N, 105°22.545'E, leg. Hunyadi, A., 01.06.2012., HA/9, PGB/1; 2012/50 Hà Giang Province, Ðồng Văn 7.5 km towards Mèo Vạc, left side of the road nr. 4C, 1260 m, 23°14.981'N, 105°23.657'E, leg. Hunyadi, A., 01.06.2012., HA/6jb; Vn11-141 Hà Giang Province, km 105.5 on road 4c, between Yên Minh and Đồng Văn (NE of Hà Giang town), 23°08.996'N, 105°10.332'E, leg. Hemmen, Ch. & J., 21.03.2011., HE/16; Vn11-144 Hà Giang Province, km 149.4 on road 4c, between Đồng Văn to Mèo Vạc (NE of Hà Giang Town), 23°15.507'N, 105°22.564'E, leg. Hemmen, Ch. & J., 23.03.2011., HE/4; Vn11-145 Hà Giang Province, km 153 on road 4c, between Đồng Văn to Mèo Vạc (NE of Hà Giang Town), left side of road, 23°14.738'N, 105°23.786'E, leg. Hemmen, Ch. & J., 23.03.2011., HE/1; Vn11-123A Hà Giang Province, ca. 7.5 km from Đồng Văn to Mèo Vạc (right side off road), 23°14.906'N, 105°23.445'E, leg. Hemmen, Ch. & J., 23.03.2011., HE/3.

Diagnosis

Shell very small to small, discoid, polished with very weak apertural rim, weak or missing callus and without apertural fold. Parietal wall with two lamellae and an upper and a lower horizontal plica; the plicae can be free from the anterior lamella or in contact with it; palatal plicae straight, parallel, horizontal, sometimes connected with a slight ridge (Figures 15E–G).

Measurements

(in mm): D = 8.9–9.9, H = 4.8–5.0 (n=4, MNHN-IM-2012-2251); D = 10.2–11.1, H = 5.3–5.6 (n=3, 2012/47); D = 10.2–11.2, H = 4.8–5.4. (Chinese specimens, n=4, see Páll-Gergely and Hunyadi 2013).

Differential diagnosis

The Chinese Gudeodiscus yunnanensis has a similar shell shape but possesses only one vertical parietal lamella (the anterior one is absent). The two species can be separated only the basis of the presence or absence of the anterior lamella. In G. soosi and in most specimens of G. multispira, few denticles are present between the upper and lower plicae, at the place of the anterior lamella. Moreover, G. multispira has a greater number of whorls and the last whorl is wider in relation to the previous one than in G. cyrtochilus. Gudeodiscus infralevis is larger with a more elevated spire, stronger apertural lip and usually a weak apertural fold. See also under G. fischeri.

Intraspecific diversity

Low; shell characters rather stable. The parietal plicae and lamellae and their respective position (reaching each other or not) show some diversity within the species. The palatal plicae are not variable, but in some shells they are connected to each other with a ridge, whereas in others they are free. It is possible that mature specimens tend to have a connection between the plicae. The species is easily recognisable and can be separated from other plectopylid species without major problems.

Distribution

(see Figure 41): The species was described from “Muong-Kong” (=Mường Khương, Lào Cai Province; see Figure 39). Material is noted from northeast of this locality, from northern Hà Giang Province and eastern parts of Yunnan Province (China) (see Páll-Gergely and Hunyadi 2013).

Remarks

The drawing in the original description of Gudeodiscus cyrtochilus is incomplete (the posterior lamella was omitted).

Some fresh shells have a characteristic mosaic structure on the dorsal surface (yellowish and darker reddish areas are following each other). This coloration is known in some “Chersaecia” (munipurensis Godwin-Austen, 1875, oglei Godwin-Austen, 1879, serica Godwin-Austen, 1875) and Plectopylis (e.g. anguina Gould, 1847, bensoni Gude, 1914, karenorum W. Blanford, 1865) species.

Gudeodiscus (Gudeodiscus) dautzenbergi (Gude, 1901)

Figures 8E–F, 9K–L, 14A–G

1901a Plectopylis Dautzenbergi Gude, Journal de Conchyliologie, 49: 198–200., Figs 1a–f. Plate 6, Figs 1a–c. [“That Khé (le type); entre Cho-Moï et Bac-Kan; entre Bac-Kan et Nac-Ri”]

1901a Plectopylis persimilis Gude, syn. n., Journal de Conchyliologie, 49: 209–211., Figs 7a–f, Plate 6, Figs 7a–c. [“Environs de That-Khé”].

1959–1960 Plectopylis schlumbergeri, — Zilch, Handbuch der Paleozoologie, 6 (2) Euthyneura: Fig. 2094.

2013 Gudeodiscus dautzenbergi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Tonkin, That-Khé, MNHN 24603 (holotype of dautzenbergi, Figure 8E); Environs de That-Khé, leg. Messager (n. 22.), MNHN 24602 (holotype of persimilis, Figure 8F).

Museum material examined

Tonkin, Nja-Ba-Thà, coll. Dosch ex Rolle, SMF 341738/1; Tonkin, That-Khé, coll. Dorsch ex Rolle ex Messager, SMF 172083/2; Tonkin, coll. Jetschin ex Bonnet 1900, SMF 102823/1; Fr. Indochina, Tonkin, That Ké, leg. Demange, 1911, HNHM 10278/2; Tonkin, coll. Sayer 1969, MNHN-IM-2012-2273/1; Tonkin, coll. Letellier 1949, MNHN-IM-2012-2274/1; Bac-Kan, leg. Messager 1904, coll. Lavezzari, 1929, MNHN-IM-2012-2290/5; Tonkin, leg. Messager, MNHN-IM-2012-2292/2; Bac-Kan, leg. Messager, MNHN-IM-2012-2297/2; Tonkin, coll. Denis 1946, MNHN-IM-2012-2303/4; Bac-Kan, leg. Messager, MNHN-IM-2012-2314/7; That Khé, leg. Messager, MNHN-IM-2012-2327/4; Bac-Kan, leg. Messager, MNHN-IM-2012-2331/5; Bac-Kan, leg. Messager, MNHN-IM-2012-2437/1; Bac-Kan et That Khé, coll. Staadt 1969, MNHN-IM-2012-2280/2; Na-Ri, leg. Messager, MNHN-IM-2012-2461/1; That-Khé, leg. Messager, MNHN-IM-2012-2373/6; That-Khé, leg. Messager, MNHN-IM-2012-2378/4; Bac-Kan, leg. Messager, MNHN-IM-2012-2382/4; Bac-Kan, leg. Messager, MNHN-IM-2012-2383/4+14jb; Bac-Kan, leg. Messager, MNHN-IM-2012-2402/3; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2336/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2337/26+2jb; That-Khé, leg. Messager, MNHN-IM-2012-2354/4; Cao-Bang, leg. Messager, MNHN-IM-2012-2360/1; Tonkin, That-Khé, coll. Salisbury ex Beddome, Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130614/2; Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130615/1; Tonkin, coll. Trechmann, Acc. no. 2176, NHMUK 20130616/2; Tonkin, That Ke (?), coll. Kennard, A. S. ex auct. (Gude), NHMUK 20130617/1; Tonkin, That-Khe, coll. Rolle, 4/11/08, NHMUK 20130618/2; Tonkin, That-Khé, 13/6/03, NHMUK 20130619/2; Tonkin, That-Khé, NHMUK 1901.7.11.1/1; Tonkin, That-Khé, NHMUK 1920.1.20.18/1; Tonkin, That-Khé, NHMUK 1908.12.21.142–143/2; Tonkin, That-Khé, NHMW 46024/1; Tonkin, That-Khé, coll. Rolle, NHMW 92559/2; Tonkin, That-Khé, coll. Oberwimmer, NHMW 71640/O/10285/1; Tonkin, That-Ke, coll. Wagner ex Messager, NHMW 71640/O/10285/1 (mixed sample with schlumbergeri); Bac Kan, coll. Steenberg, ZMUC-GAS-1084/1; Tonkin, coll. Steenberg, ZMUC-GAS-1805/2.

New material examined

Vn10-44 Bắc Kạn Province, Chợ Mới (left bank of river); 21°52.682'N, 105°47.078'E, leg. Hemmen, Ch. & J., 17.03.2010., PGB/3; Vn10-42 Thái Nguyên/Bắc Kạn Province, ca. 1 km S of Chợ Mới; 21°52.707'N, 105°46.172'E, leg. Hemmen, Ch. & J., 17.03.2010., PGB/3; 2011/103 Bắc Kạn Province, Chợ Mới, eastern bank of the river, Khuôn Thung cross 500 m towards Quảng Chu Commune, right side of the road, 21°52.508'N, 105°47.328'E, leg. Hunyadi, A., 21.11.2011., HA/10+4jb, PGB/1; 2011/104 Thái Nguyên Province, Chợ Chu (=Chu Market), rocky wall above the NE part of the village, 90 m, 21°54.613'N, 105°39.195'E, leg. Hunyadi, A., 21.11.2011., HA/3.

Diagnosis

Shell medium-sized or large, with irregular growth lines, but appearing almost smooth; spire slightly elevated, apertural lip thick but blunt; apertural fold strong and oblique, connected to the callus, but reaching its maximum height some distance from the callus (Figures 9K–L). Parietal wall with two parietal lamellae; the anterior one has an anteriorly conspicuously elongated lower “leg”; this structure may have resulted from the connection of the anterior lamella and the lower plica; middle palatal plicae oblique (Figures 14A–G).

Measurements

(in mm): D = 16.7–20.6, H = 8.9–9.8 (n=3, Vn10-42); D = 16.1–17.8, H = 7.9–9.2 (n=2, Vn10-44).

Differential diagnosis

Gudeodiscus villedaryi, which is probably the closest relative, differs from G. dautzenbergi by the presence of an additional horizontal parietal plica under the vertical lamellae, near the suture. Distinguishing G. dautzenbergi from some similar looking populations of G. villedaryi is impossible without breaking the shell and observing the parietal plicae. Most populations of G. villedaryi however, have a sharp periumbilical keel, which always absent in G. dautzenbergi (see also Remarks under G. villedaryi). Gudeodiscus dautzenbergi is flatter and more widely umbilicated than G. giardi. The latter species has a domed shell, thinner shell wall and thicker peristome. For comparisons with Halongella schlumbergeri, see under that species. Distinguishing G. dautzenbergi from H. schlumbergeri requires experience, but is possible without breaking the shell on the basis of the formation of the peristome and the apertural fold (Figures 9K–N).

Intraspecific diversity

Low; shell characters stable.

Distribution

(see Figure 40): This species as well as Plectopylis persimilis (synonym of Gudeodiscus dautzenbergi) were described from That-Khé (northern Lạng Sơn Province) (see Figure 39). Our newly-collected material is from the border region of the Thái Nguyên and Bắc Kạn provinces.

Remarks

The holotype of Plectopylis persimilis and that of Plectopylis dautzenbergi do not show significant differences in terms of shell shape, size, aperture shape and the formation of the plicae and lamellae; therefore we synonymise Plectopylis persimilis with P. dautzenbergi. These two species were described in the same publication (Gude 1901a), therefore the name introduced earlier (dautzenbergi, page 198) is considered a senior synonym.

Gudeodiscus dautzenbergi and G. villedaryi are separated here on the basis of the presence or absence of a lower plica, although the two species may be conspecific. More information is necessary to clarify the distinctness of G. dautzenbergi.

The specimen figured by Zilch (1960, Fig. 2094) under the name Plectopylis (Endoplon) schlumbergeri is missing. There is a note written by Zilch saying that he found the box empty on 11.12.1963 (Ronald Janssen, pers. comm., October 2013). Although the specimen could not be examined by us, we are confident in stating that the figure shows a shell of Gudeodiscus dautzenbergi.

Gudeodiscus (Gudeodiscus) fischeri (Gude, 1901)

Figures 2E, 3A–C, 9P–Q, 15H–R, 17, 18, 28D, 29D, 29J, 30E, 31D, 34M–O

1901a Plectopylis Fischeri Gude, Journal de Conchyliologie, 49: 204–205., Figs 4a–e, Plate 6, Figs 4a–c. [“Environs de Bac-Kan”].

1901a Plectopylis tenuis Gude, syn. n., Journal de Conchyliologie, 49: 202–204, 205., Figs 3a–e, Plate 6, Figs 3 a–c. [“Cho-Ra (le type); environs de Bac-Khan; environs de Cho Moi”].

1905b Plectopylis Fischeri, — Dautzenberg & Fischer, Journal de Conchyliologie, 53: 360. [“Ha Giang”].

1909 Plectopylis tenuis, — Gude, Proceedings of the Malacological Society of London, 8: 215, 216.

2013 Gudeodiscus fischeri, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus tenuis, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Tonkin, Environs de Bac-Kan, leg. Messager, MNHN 24579 (holotype of fischeri, Figure 3B); Tonkin, Cho-Ra, leg. Messager, MNHN 24587 (holotype of tenuis, Figure 3C).

Museum material examined

Tonkin, Bac-Kan, NHMUK 1908.12.21.144/1; Tonkin, environs de Bac-Kan, leg. Messager, (n. 28), RBINS/2; Tonkin, Ha-Giang, leg. Messager, RBINS/5; Ha Giang, leg. Mansuy, coll. M. H. Fischer, MNHN-IM-2012-2241/12 adult, 1jb; Ha Giang, coll. Mansuy, MNHN-IM-2012-2257/5; Tonkin, leg. Messager, MNHN-IM-2012-2390/1; Cho-Ra, leg. Messager, MNHN-IM-2012-2477/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2466/3; Tonkin, Cho Rah, ex Rolle, USNM 207813/2 („tenuis“); Nga-Son, leg. Messager, MNHN-IM-2012-2233/2 („tenuis“); Nga-Son, leg. Messager, MNHN-IM-2012-2253/2 (“tenuis”); Tonkin, coll. Denis, 1946, MNHN-IM-2012-2338/3 (“tenuis”); Cho-Ra, leg. Messager, MNHN-IM-2012-2361/1 (“tenuis”); Tonkin, Bac-Kan, coll. Rolle, NHMW 71640/O/14028/1.

New material examined

20090519B Tuyên Quang Province, Hàm Yên District, Yên Phú Commune, Đồng Tiến, Thống Nhất, ca 70 m, 22°08.673'N, 104°58.634'E, leg. Ohara, K., 19.05.2009., OK/12, PGB/3; 20090515C Bắc Kạn Province, Ba Bể District, Ba Bể Nat. Park, Khâu Kum, ca 185 m, 22°26.465'N, 105°36.642'E, leg. Ohara, K., 15.05.2009., OK/8, PGB/2; 20081113C Hà Giang Province, Hà Giang Town, Ngọc Đường Commune, Bản Cườm (= Cườm Village), ca 110 m, 22°51.180'N, 105°01.075'E, leg. Ohara, K., 13.11.2008., OK/1, PGB/1; Vn10-118 Hà Giang Province, Tâm Village, ca. 7–8 km SE of Hà Giang (between Vị Xuyên and Bản Hãm = “Hãm Village”), 22°48.019'N, 105°00.888'E, leg. Hemmen, Ch. & J., 16.10.2010., PGB/2; Vn11-138 Tuyên Quang Province, near Tôn Hông, road #185 from Tuyên Quang to Vĩnh Lộc (formerly Chiêm Hóa) (NE of Tuyên Quang), leg. Hemmen, Ch. & J., 19.03.2011., HE/1, PGB/1 (anatomically examined, see Figures 17, 28D, 29J, 31D, 34M–O); Vn10-120 Hà Giang Province, ca. 9.8 km from Hà Giang to Tam Sơn (formerly Quản Bạ), left side off road, 22°52.907'N, 104°59.885'E, leg. Hemmen, Ch. & J., 17.10.2010., PGB/3; 2012/56 Hà Giang Province, Hà Giang 7 km towards Tam Sơn, left side of the road nr. 4C, 100 m, 22°51.650'N, 105°00.768'E, leg. Hunyadi, A., 03.06.2012., HA/4; 2012/57 Hà Giang Province, Hà Giang 9.8 km towards Tam Sơn, left side of the road 4C, 120 m, 22°52.881'N, 104°59.927'E, leg. Hunyadi, A., 03.06.2012., HA/20+7jb, PGB/2; Vn11-179 Tuyên Quang Province, ca. 5.5 km E of Chương Dương (left bank of Lô River), leg. Hemmen, Ch. & J., 30.09.2011., HE/2; 20090517A Bắc Kạn Province, Ba Bể District, Ba Bể Nat. Park, along the trekking road, near guest house, 205 m, 22°25.049'N, 105°37.699'E, leg. Ohara, K., 17.05.2009., OK/8, PGB/2 (“tenuis”, anatomically examined, see Figure 29D); Vn10-28A Bắc Kạn Province, ca 1 km from Ba Bể Nat. Park, headquarters to Ba Bể Lake, 22°24.829'N, 105°37.652'E, leg. Hemmen, Ch. & J., 20.10.2010., PGB/6 (“tenuis”); Vn09-26 Bắc Kạn Province, Ba Bể Nat. Park, near bungalows (at Park Headquarters), leg. Hemmen, Ch. & J., 17.10.2009., HE/2 (“tenuis”); 2011/91 Bắc Kạn Province, Ba Bể Nat. Park, path starting from the bungalows 500 m, 240 m, 22°25.072'N, 105°37.941'E, leg. Hunyadi, A., 17.11.2011., HA/11+5jb, PGB/2 (“tenuis”); 2011/96 Bắc Kạn Province, Ba Bể Nat. Park, Thẳm Kịt Cave 2 km from the look-out tower, 335 m, 22°24.686'N, 105°37.710'E, leg. Hunyadi, A., 19.11.2011., HA/29+3jb, PGB/2 (“tenuis”, anatomically examined, see Figure 18); 2011/97 Bắc Kạn Province, Ba Bể Nat. Park, Thẳm Kịt Cave 1 km from the look-out tower, no GPS data, leg. Hunyadi, A., 19.11.2011., HA/8+4jb (“tenuis”).

Diagnosis

Shell small to medium-sized, with smooth basal and usually finely ribbed apical surface (in some populations also smooth and glossy, see Figure 2E); shell usually flat, or with very slightly elevated spire, or only the protoconch is elevated from the dorsal surface; callus and apertural fold (if present) weak (Figures 9P–Q). Parietal wall with two lamellae (the anterior is exceptionally dissolved into small denticles); middle palatal plicae oblique, depressed Z or L-shaped, they are free or sometimes connected to each other (Figures 15H–N).

Measurements

(in mm): D = 16.6–18.6, H = 7–7.9 (n=3, Vn10-120); D = 12.1–12.4, H = 4.8–5.3 (n=3, 20090519B); D = 15.5–15.9, H = 7.1–7.2. (n=2, 20090515C); D = 14.6, H = 7.4–7.6. (n=2, 2011/91); D = 12.9–14.7, H = 6.4–7.3 (n=6, Vn10-28A).

Differential diagnosis

Gudeodiscus cyrtochilus is smaller than G. fischeri, it has a narrower umbilicus, more regularly growing whorls (the last whorl is only slightly wider than the penultimate one), a shorter lower horizontal parietal plica and no apertural fold. The Chinese G. multispira and G. soosi are also smaller, have a greater number of densely-coiled whorls and at the position of the anterior lamella there are usually 2–4 clearly separated denticles (see also Remarks). In some populations of G. multispira the denticles are missing so that only the posterior lamella is present. Gudeodiscus yunnanensis has no anterior lamella, just a curved single lamella (homologous with the posterior lamella). Gudeodiscus eroessi never has an apertural fold and its anterior lamella is dissolved into small denticles, or missing. Gudeodiscus infralevis and G. suprafilaris have a more elevated spire, narrower umbilicus and rather straight, horizontal, parallel plicae.

Intraspecific diversity

The variability is quite large in terms of shell size and shape, sculpture, strength of the callus and apertural fold and the formation of parietal plicae and lamellae. The combination of weak callus and apertural fold and the “nautiliform” shape helps in the identification of the species. See also Table 7.

Diversity of shell characters within the species Gudeodiscus (Gudeodiscus) fischeri. Abbreviations: OAE: only apex elevated.

code callus and apertural fold anterior lamella lamella and lower plica shells opened shell spire remarks
2012/57= Vn10-120 strong dissolved not in contact 2 thick, greyish slightly elevated large
2012/56 strong normal connected 1 thick, greyish slightly elevated
20081113C strong normal connected 1 thick, greyish slightly elevated
Vn10-118 strong normal connected 1 thick, greyish OAE
20090515C weak normal connected 2 thin, translucent, corneous slightly elevated typical fischeri
20090519B weak normal connected 2 very thin, translucent, yellowish OAE small
2011/96= 2011/91= 2009.05.17A= Vn10-28A weak normal not in contact 5 thin, translucent, corneous elevated typical tenuis

Description of the genitalia

Two specimens were dissected, belonging to two different populations: “Specimen1” Tuyên Quang Province, near Tôn Hông, road #185 from Tuyên Quang to Vĩnh Lộc (formerly Chiêm Hóa) (NE of Tuyên Quang), leg. Hemmen, Ch. & J., 19.03.2011. (specimen without embryos in the uterus, but with calcareous hooks inside the penis, Figure 17, 31D); “Specimen2” Bắc Kạn Province, Ba Bể Nat. Park, Thẳm Kịt Cave 2 km from the look-out tower, 335 m, 22°24.686'N, 105°37.710'E, leg. Hunyadi, A., 19.11.2011. (typical Plectopylis tenuis; with a developing embryo in the uterus, Figure 18).

The penis is a cylindrical tube with several longitudinal, parallel folds on the inner wall; there are pockets formed by some of these folds; in the wall of the opened penis the series of pockets are arranged along a bell-shaped line (Figure 28D); there were calcareous hooks within the pockets of “Specimen1”; the base of the hooks were elongated, they lay within the pockets, whereas the tip portion projects out of the pockets (Figure 30E); epiphallus as long as the penis, with few parallel folds in the lumen (Figure 29D); distal portion of the penis and the proximal part of the epiphallus are connected with weak membrane; more closely to the genital opening these two organs are more stronger connected; penial caecum tapers toward the end, it is about a quarter as long as the penis; its inner wall with irregular folds arranged in longitudinal lines, with calcareous granules in between (mainly at the distal end); retractor muscle attaching on the apical part of the penial caecum is approximately as long as the caecum; there is an additional retractor muscle on the proximal part of the penis. Vagina is thickened and forms a “vaginal bulb”, which is attached to the body wall with several thin ligaments; inner wall of the vaginal bulb and the distal part of the vagina with well-developed, longitudinal, serrulate folds (Figure 31D); stem of the gametolytic sac is long and slim; it is attached hardly to the spermoviduct; diverticulum well-developed, free; the diverticulum of the specimen from the Ba Bể Nat. Park contained three long, slightly C-shaped spermatophores; the proximal side of the spermatophores were damaged, thus they might have been connected; spermoviductus slim and long.

Besides the presence or absence of embryos and calcareous penial hooks between the two specimens the only notable difference is the longer retractor muscle in “Specimen2” than in “Specimen1”, but the taxonomic value of this character is unknown.

Radula

See Table 6 and Figures 34M–O.

Distribution

(see Figure 41): Gudeodiscus fischeri is known from Hà Giang, Tuyên Quang and Bắc Kạn Provinces.

Remarks

Some samples from the Ba Bể Nat. Park (Vn10-28A, 20090517A, 2011/91, 2011/96) are identical with the type specimen of Plectopylis tenuis described from Cho Ra (see Figure 39). This town is situated approximately 7 km from the locality of our recent material. Some 3 km north of our tenuis localities there is a population (20090515C) which agrees with tenuis in every shell character except that the anterior parietal lamella and the lower horizontal plica are connected (typical in fischeri). Since no other shell characters are known to be different between tenuis and fischeri, and other populations of fischeri show relatively large variability in terms of several shell characters, we synonymize Plectopylis tenuis with P. fischeri.

The shells collected 9.8 km north of Hà Giang are relatively large and thick-walled, have the anterior lamella dissolved into 3–4 denticles, and have strong apertural denticle and callus (Figures 3A, 15L–M). The shells collected at Đồng Tiến are small and very glossy in appearance (Figure 2E).

Gudeodiscus (Gudeodiscus?) francoisi (Fischer, 1898)

Figures 7A–C, 13E–K

1898b Plectopylis Françoisi Fischer, Journal de Conchyliologie, 46: 214–218., Figs 1, 3–4. [“rochers calcaires Déo-Ma-Phuc”].

1899 Plectopylis Françoisi Fischer, Bulletin biologique de la France et de la Belgique, 32: 330–332., Figs 1, 3–4. [“rochers calcaires Déo-Ma-Phuc”].

1899b Plectopylis françoisi, — Gude, Science Gossip, 6: 75–76., Figs 201a–e.

1899c Plectopylis (Endoplon) françoisi, — Gude, Science Gossip, 4: 148.

1899d Plectopylis (Endoplon) françoisi, — Gude, Science Gossip, 6: 175.

1900 Plectopylis lepida Gude, syn. n., The Annals and Magazine of Natural History, 7 (5): 313. [“Tonkin, Tinh-Tuc”].

1901a Plectopylis Bavayi Gude, syn. n., Journal de Conchyliologie, 49: 200–202., Figs 2a–e, Plate 6, Figs 2a–c. [That Khé (le type); secteur de Nac-Ri].

1901b Plectopylis lepida, — Gude, Journal of Malacology, 8: 48–49., Figs 4a–f.

1908 Plectopylis Bavayi, — Dautzenberg & Fischer, Journal de Conchyliologie, 56: 177. [Quang-Huyen].

2013 Gudeodiscus francoisi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde 142 (1): 8.

2013 Gudeodiscus lepidus, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde 142 (1): 8.

Types examined

Rochers calcaires de Déo-Ma-Phuc, leg. Dr. Billet, 23.10.1892, MNHN 9945 (holotype of francoisi, Figure 7B); That-Khé, leg. Messager, MNHN 24601 (holotype of bavayi, Figure 7A); Tonkin, Tinh-Tuc, NHMUK 1922.8.29.51 (holotype of lepida, Figure 7C).

Museum material examined

Tonkin, coll. Jetschin ex Bonnet 1900, SMF 102826/1; Tonkin, That Khé, coll. Dosch ex Rolle, SMF 172090/4; Tonkin, That-Khé, coll. Dosch ex Rolle, SMF 172082/2; Tonkin, leg. Messager, MNHN-IM-2012-2227/6; Tonkin, leg. Messager, MNHN-IM-2012-2229/4; Tonkin, coll. Letellier 1949, MNHN-IM-2012-2267/1; Secteur de Nac-Ri, leg. Messager, MNHN-IM-2012-2268/5; That-Khé, coll. Lavezzari, 1929, MNHN-IM-2012-2276/5; Tonkin, leg. Messager, MNHN-IM-2012-2284/1; That Ké, Nac Ri, leg. Messager, MNHN-IM-2012-2333/8; Tonkin, leg. Messager, MNHN-IM-2012-2353/1; Na-Cham, leg. Messager, MNHN-IM-2012-2358/5; Na-Ri, leg. Messager, MNHN-IM-2012-2363/5; Tonkin, leg. Messager, MNHN-IM-2012-2428/1; Tonkin, leg. Messager, MNHN-IM-2012-2440/6; Tonkin, leg. Messager, MNHN-IM-2012-2430/7; Nac-Ri et That-Khe, coll. Staadt, 1969, MNHN-IM-2012-2386/2; Tonkin, leg. Messager, MNHN-IM-2012-2371/3; That-Khé, leg. Messager, MNHN-IM-2012-2377/30+3jb; Tonkin, That-Khé, coll. Salisbury ex Beddome, NHMUK 20130592/2; Tonkin, coll. Kennard, A. S. ex auct. (Gude), NHMUK 20130593/2; Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130594/2; Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130595/2; Tonkin, That-Khé, V.W. MacAndrew Coll, 13/6/01.114, NHMUK 20130596/2; Tonkin, NHMUK 1916.3.15.4–5/2 (“showing immature armature”); Tonkin, That Khé, NHMUK 1901.7.11.46/1; Tonkin, That-Khé, NHMUK 1908.12.21.118–119/2; Baie d’Along, coll. Staadt, 1969, MNHN-IM-2012-2311/1 (similar to the holotype of Plectopylis lepida); Tonkin, That-Khe Na-Ri, coll. Rušnov ex Rolle ex Messager, NHMW 92561/2; Tonkin, Phi-Mi, coll. Steenberg, ZMUC-1807/1; Tonkin, coll. Steenberg, ZMUC-GAS-1806/1; Tonkin, coll. Steenberg, ZMUC-GAS-1810/1.

New material examined

GS17 Bắc Kạn Province, Na Rì Distr., limestone cliffs on the left side of the road to Kim Hỷ, 2 km before Kim Hỷ, soil in small cavern, ca 560 m, 22°16.897'N, 106°2.754'E, leg. Grego, J. & Śteffek, J., 05.04.2012., JG/1, PGB/1; GS22 Bắc Kạn Province, Na Rì District, 2 km S of Bản Dền (=Dền Village), limestone rocks at side of the valley near gold quarry, in small cavern in dense rain forest, ca 590 m, 22°14.547'N, 106°0.527'E, leg. Grego, J. & Śteffek, J., 06.04.2012., JG/1; GS24 Bắc Kạn Prov, Na Rì Distr., 2 km S of Bản Dền, W slopes of a deep sinkhole covered with forest, leaf litter under high limestone wall, ca 640 m, 22°14.506'N, 106°0.521'E, leg. Grego, J. & Śteffek, J., 06.04.2012., JG/1, PGB/2; 2011/80 Cao Bằng Province, Đèo Mã Phục (pass) 1 km towards Quảng Uyên, right side of the road, 565 m, 22°43.918'N, 106°20.490'E, leg. Hunyadi, A., 14.11.2011., HA/2+2jb; 2012/41 Cao Bằng Province, Đèo Mã Phục (pass) 1 km towards Quảng Uyên, right side of the road, 570 m, 22°43.896'N, 106°20.484'E, leg. Hunyadi, A., 27.05.2012., HA/11+2jb, PGB/2.

Diagnosis

Shell small to medium-sized, yellowish or mustard-coloured, glossy, with slowly increasing whorls, deep umbilicus, domed dorsal side; thin apertural lip and well-developed apertural fold. Parietal wall with two parietal lamellae; the anterior one is connected to the lower plica; middle palatal plicae oblique, depressed Z-shaped (Figures 13E–K).

Measurements

(in mm): D = 13.2, H = 6.7 (holotype of lepida); D = 19.6–19.8, H = 10.4–10.7 (N = 2, NHMUK 20130593); D = 17.8–18.0, H = 9.8–9.9 (n=2, NHMUK 1908.12.21.118–119).

Differential diagnosis

The glossy, dark yellow shell, the characteristic apertural fold and shell shape makes this species easily distinguishable from most congeners. Gudeodiscus francoisi has a smoother shell, weaker apertural lip and more regular whorls than G. giardi giardi. In the type locality of francoisi (Déo-Ma-Phuc, see Figure 39) the species lives together with G. giardi giardi. In some cases the two species can be hardly distinguished, especially in the case of subadult giardi specimens which cannot be easily distinguished from francoisi. The possibility of hybridisation in that locality cannot be excluded; however specimens from other localities are easily distinguishable.

Intraspecific diversity

The species shows little intraspecific variability in terms of shell characters. The “lepida-like” shells are considered to the results of abnormal growth.

Distribution

(see Figure 42): Newly-collected material from Cao Bằng and Bắc Kạn Provinces was examined. There is a single shell which is identical to the holotype of Plectopylis lepida and is labelled as being collected from Hạ Long Bay, but this collection locality is probably incorrect.

Remarks

Gudeodiscus bavayi is a synonym of G. francoisi. The two holotypes are identical in shell shape and arrangement of the inner lamellae. The only difference is that the holotype of G. francoisi lacks an apertural fold because it is a subadult shell. Other shells collected from the type locality are identical with the holotype of Plectopylis bavayi. Plectopylis lepida was described on the basis of a single shell. During the revision of the Vietnamese Plectopylidae material in the MNHN, we found a single shell (Baie d’Along, coll. Staadt, 1969, MNHN-IM-2012-2311) which is identical in shell shape and plication with the holotype of lepida. These two shells differ from G. francoisi only by the absence of the posterior lamella and the weak apertural fold. The absence of the posterior lamella is probably the result of unusual development, which is also visible in a specimen of G. suprafilaris (see under that species). The weak apertural fold can be explained by subadult stages of these shells. Since no other shell characters distinguish Plectopylis lepida and G. francoisi, the former is treated as a junior synonym of Plectopylis francoisi.

Gudeodiscus (Gudeodiscus) giardi giardi (Fischer, 1898)

Figures 7E–F, 8A, 9I, 13L–U, 19, 28B, 29E, 30D, 32C, 35A–C, 45A

1898a Plectopylis Giardi Fischer, Bulletin Biologique de la France et de la Belgique, 28: 320–322., Plate 17, Figs 17–21. [“Cao-Bang”].

1898b Plectopylis Giardi Fischer, Journal de Conchyliologie, 46: 214–218., Figs 2, 5–6. [“rochers calcaires Déo-Ma-Phuc”].

1899 Plectopylis Giardi Fischer, Bulletin Biologique de la France et de la Belgique, 32: 330–332., Figs 2, 5–6.

1899a Plectopylis giardi, — Gude, Science Gossip, 5: 332–333., Figs 95a–e [“Cao-Bang, Tonkin”].

1899a Plectopylis congesta Gude, syn. n., Science Gossip, 5: 332–333., Figs 96a–f [“Tonkin”, “Its exact locality, unfortunately, was not stated.”].

1899b Plectopylis giardi, — Gude, Science Gossip, 6: 76., Fig. 103.

1899c Plectopylis (Endoplon) giardi, — Gude, Science Gossip, 4: 148.

1899c Plectopylis (Endoplon) congesta, — Gude, Science Gossip, 6: 148.

1899d Plectopylis (Endoplon) giardi, — Gude, Science Gossip, 6: 175.

1899d Plectopylis (Endoplon) congesta, — Gude, Science Gossip, 6: 175, 176.

1901a Plectopylis congesta, — Gude, Journal de Conchyliologie, 49: 199, 202, 209, 211–212. [“Entre Bac-Kan, et Nac-Ri; environs de Bac-Kan; That-Khé”].

1908 Plectopylis Giardi, — Gude, Journal de Conchyliologie, 55: 346–348., Figs 1a–b [“Cao-Bang”, “Quang-Huyen”].

2013 Gudeodiscus congestus, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus giardi giardi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 19–20., Figs 28, 53a–b, 58 (map).

Types examined

Haut-Tonkin, Cao-Bang, leg. Billet, M., MNHN 9946 (2 syntypes of giardi, Figure 8A); Vietnam, Tonkin, environs de Bac-Kan, leg. Messager, MNHN IM-2010-12120 (syntype of congesta, Figure 8E); Vietnam, Tonkin, environs de Bac-Kan. leg. Messager, NHMUK 1922.8.29.49 (syntype of congesta, Figure 8F).

Museum material examined

Tonkin, coll. Jetschin ex Bonnet 1900, SMF 341736/2; Tonkin, Möllendorff ex Fulton, SMF 150136/1; Tonkin, coll. Jetschin ex Berlier 1908, SMF 102817/1; Tonkin, environs de Bac-Kan, leg. Messager (n. 28), RBINS/1; Tonkin, Long-Phai, NHMSB 122815/1; Long-Phai, leg. Messager, 1901, MNHN-IM-2012-2231/13; Nga-Son, leg. Messager, MNHN-IM-2012-2235/1; Long-Phai, leg. Messager, 1901, MNHN-IM-2012-2236/16; Quang-Huyen, leg. Mansuy, MNHN-IM-2012-2238/14; Bac-Kan, leg. Messager, MNHN-IM-2012-2239/7; That-Khé, leg. Messager, MNHN-IM-2012-2240/9; Bac-Kan, leg. Messager, MNHN-IM-2012-2246/8; Quang-Huyen, Ha-Lang, Coll. Mansuy, MNHN-IM-2012-2248/14; That-Khé, coll. Letellier 1949, MNHN-IM-2012-2266/1; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2278/1; Tonkin, coll. Letellier, 1949, MNHN-IM-2012-2293/1; Tonkin, coll. Mansuy, MNHN-IM-2012-2298/1; Entre Bac-Kan et Nac-Ri, coll. Lavezzari, 1929, MNHN-IM-2012-2302/6; Tonkin, coll. Letellier, 1949, MNHN-IM-2012-2308/1; Tonkin, coll. Levazzari, 1929, MNHN-IM-2012-2309/3; That-Khé, leg. Messager, MNHN-IM-2012-2310/6; Cao-Bang, leg. Messager, MNHN-IM-2012-2469/7; Tonkin, leg. Messager, MNHN-IM-2012-2460/9; Tonkin, leg. Messager, MNHN-IM-2012-2441/1; Halong Bay, leg. Messager, MNHN-IM-2012-2318/1; Halong Bay, leg. Messager, MNHN-IM-2012-2319/1; Halong Bay, leg. Messager, MNHN-IM-2012-2323/1; Tonkin, Bac-Kan, Na-Ri, leg. Messager, MNHN-IM-2012-2324/47; That Khé, leg. Messager, MNHN-IM-2012-2326/3; Po Ma, leg. Messager, MNHN-IM-2012-2328/7; That Khé, coll. Staadt 1969, MNHN-IM-2012-2330/3; That Khé, leg. Messager, MNHN-IM-2012-2341/28; Po Ma, leg. Messager, MNHN-IM-2012-2342/6; Col de Nuages, leg. Messager, MNHN-IM-2012-2343/4; Bac-Kan, leg. Messager, MNHN-IM-2012-2344/8; Tonkin, leg. Messager, MNHN-IM-2012-2345/8; That Khé, leg. Messager, MNHN-IM-2012-2346/5; Cold de Nuages, leg. Messager, MNHN-IM-2012-2349/4; Quang-Huyen, coll. Staadt, 1969, MNHN-IM-2012-2351/1; Tonkin, leg. Messager, MNHN-IM-2012-2352/10; Tonkin, leg. Messager, MNHN-IM-2012-2355/1; Na-Cham, leg. Messager, MNHN-IM-2012-2356/10; Na-Cham, leg. Messager, MNHN-IM-2012-2357/5; Cao-Bang, leg. Messager, MNHN-IM-2012-2359/4; That-Khé, leg. Messager, MNHN-IM-2012-2374/4; Tinh Tuc, secteur de Nguyen Binh, coll. Achat Boubée, MNHN-IM-2012-2385/1; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2393/1; Tonkin, coll. Jousseaume, MNHN-IM-2012-2399/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2432/1; Tonkin, leg. Messager, MNHN-IM-2012-2426/3; Bac-Kan, leg. Messager, MNHN-IM-2012-2435/1; Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130604/2 (under the name “persimilis”); Tonkin, 3/10/08, NHMUK 20130605/2 (under the name “persimilis v. minor”); Tonkin, That-Khé, 3/10/08, NHMUK 20130606/3 (under the name “persimilis”); Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130607/1; Tonkin, 27/6/00, 28, NHMUK 20130608/3 (“congesta”); Tonkin, Phi-Mi, coll. Salisbury ex Beddome, NHMUK 20130609/2 (“congesta”); Tonkin, coll. Kennard, A. S. ex Gude, NHMUK 20130610/1 (“congesta”); Tonkin, Quang-Huyen, NHMUK 1916.3.16.21/1; Tonkin, Quang-Huyen, NHMUK 1907.2.20.17–18/2; Haut-Tonkin, NHMUK 1904.8.1.1–2/2 (under the name “persimilis”); Tonkin, That-Khé, NHMUK 1900.2.13.221/1; Tonkin, That-Khé, NHMUK 1920.1.20.17/1; Tonkin, Long-Phai, coll. Wagner ex Messager, NHMW 71640/O/10289/1; Tonkin, Ngan-Son, coll. Wagner ex Messager, NHMW 71640/O/10288/1; Tonkin, Phi-Mi, NHMW 46023/2; Tonkin, Long-Phai, NHMW 46294/2; Tonkin, That-Khe, coll. Wagner ex Messager, NHMW 71640/O/10286/1; Tonkin, Po-Ma (?), coll. Wagner ex Messager, NHMW 71640/O/10287/1; Tonkin, Bac-Khuon, coll. Rolle, NHMW 103352/1 (mixed sample with phlyarius); Tonkin, Quang-Huyen, coll. Steenberg, ZMUC-GAS-1813/2.

New material examined

Vn10-58 Cao Bằng Province, ca. 31.5 km from Phục Hòa to Mã Phục (left off rd.), 22°42.212'N, 106°22.055'E, leg. Hemmen, Ch. & J., 20.3.2010., PGB/1; Vn10-61 Cao Bằng Province, ca. 2 km from Quảng Uyên to Hạ Lang (right off rd.) 22°42.685'N, 106°27.232'E, leg. Hemmen, Ch. & J., 24.3.2010., PGB/2; Vn10-59 Cao Bằng Province, ca. 30 km from Phục Hòa to Mã Phục (right off rd.), 22°41.787'N, 106°22.652'E, leg. Hemmen, Ch. & J., 23.3.2010., PGB/3; Vn09-23 Cao Bằng Province, ca. 4.5 km from Mã Phục to Cao Bằng (NW of Cao Bằng), ca. 400 m, 22°42.814'N, 106°19.630'E, leg. Hemmen, Ch. & J., 16.10.2009., PGB/4; Vn10-57 Cao Bằng Province, ca. 4.5 km from Mã Phục to Cao Bằng (left off rd.), 22°42.661'N, 106°19.627'E, leg. Hemmen, Ch. & J., 23.03.2010., PGB/3; 20081115D Cao Bằng Province, Hòa An District, Nguyễn Huệ Commune, Hạ Lang, ca 390 m, 22°42.703'N, 106°19.606'E, leg. Ohara, K., 15.11.2008., OK/6, PGB/1; 20081116C Cao Bằng Province, Trùng Khánh District, Cảnh Tiên Commune, Pắc Rảo., ca 545 m, 22°48.941'N, 106°30.549'E, leg. Ohara, K., 16.11.2008., OK/7, PGB/2; Vn10-69 Cao Bằng Province, ca. 34.5 km from Cao Bằng to Đông Khê (left off new rd.), 22°27.439'N, 106°24.994'E, leg. Hemmen, Ch. & J., 26.03.2010. (typical “congesta”), PGB/3; 2011/81 Cao Bằng Province, Đèo Mã Phục (pass) 500 m towards Quảng Uyên, left side of the road, rock cavern, 610 m, 22°43.981'N, 106°20.333'E, leg. Hunyadi, A., 14.11.2011., HA/26, PGB/2; 2011/82 Lạng Sơn Province, Lũng Phầy (pass), Thất Khê N 13 km, 475 m, 22°20.363'N, 106°27.098'E, leg. Hunyadi, A., 15.11.2011., HA/8, PGB/1 (typical “congesta”); 2011/83 Cao Bằng Province, Đèo Lũng Phầy (pass) 2.5 km towards Đông Khê, right side of the road, 360 m, 22°21.654'N, 106°26.467'E, leg. Hunyadi, A., 15.11.2011., HA/17, PGB/2 (typical “congesta”); 2011/86 Cao Bằng Province, Quảng Uyên N, 206–207 cross, 300 m towards Hạ Lang, right side of the road, 445 m, 22°42.670'N, 106°27.260'E, leg. Hunyadi, A., 16.11.2011., HA/14, PGB/1; 2011/87 Cao Bằng Province, Quảng Uyên N, 206–207 cross, 430 m, 22°42.737'N, 106°27.223'E, leg. Hunyadi, A., 16.11.2011., HA/14, PGB/1 (anatomically examined, Figures 19, 28B, 29E, 30D, 32C, 35A–C); 2011/88 Cao Bằng Province, Quảng Uyên NW, 445 m, 22°42.562'N, 106°26.313'E, leg. Hunyadi, A., 16.11.2011., HA/6; 2011/89 Cao Bằng Province, Quảng Uyên W, Phi Hải-Ðầu Tuyền cross, 500 m, 22°42.188'N, 106°26.358'E, leg. Hunyadi, A., 16.11.2011., HA/5; 2011/90 Cao Bằng Province, Quảng Uyên S 2 km towards Hồng Ðịnh, left side of the road, 470 m, 22°40.761'N, 106°26.746'E, leg. Hunyadi, A., 16.11.2011., HA/1; 2012/42 Cao Bằng Province, Quảng Uyên 10 km towards Cao Bằng, left side of the road, 620 m, 22°42.772'N, 106°21.582'E, leg. Hunyadi, A., 27.05.2012., HA/9; 2012/43 Cao Bằng Province, Pắc Rảo, Cảnh Tiên Commune cross, 300 m towards Trùng Khánh, right side of the road, 530 m, 22°49.385'N, 106°30.742'E, leg. Hunyadi, A., 28.05.2012., HA/13; 2012/44 Cao Bằng Province, southern edge of Pắc Rảo, Trùng Khánh 3 km towards Quảng Uyên, left side of the road, 570 m, 22°48.961'N, 106°30.533'E, leg. Hunyadi, A., 28.05.2012., HA/35; 2011/85 Cao Bằng Province, Cao Bằng 34.5 km towards Đông Khê, left side of the road, 500 m, 22°27.487'N, 106°25.047'E, leg. Hunyadi, A., 15.11.2011., HA/35, PGB/5 (typical “congesta”); 2011/84 Cao Bằng Province, Đông Khê 3 km towards Đèo Lũng Phầy (pass), right side of the road, 390 m, 22°24.223'N, 106°25.937'E, leg. Hunyadi, A., 15.11.2011., HA/10, PGB/2 (typical “congesta”); Cao Bằng Province, Hòa An District, Nguyễn Huệ Commune, small hill just outside of Khau Trang Village, 22°33.510'N, 106°10.294'E, leg. Naggs, F. et al., 22.06.2011., NHMUK/1 (see Figure 45A).

Diagnosis

Shell small to large, brownish (some Chinese populations are small and yellow, translucent), usually finely reticulated (resulting in a matt surface), umbilicus deep, dorsal side domed; apertural lip, callus and apertural fold very well-developed (Figure 9I). Parietal wall with two lamellae; the anterior one is usually connected to the lower plica; middle palatal plicae short, depressed Z-shaped, or almost vertical, sometimes connected to each other (Figures 13L–U).

Measurements

(in mm): D = 13.5–14.1, D = 7–7.7 (n=2, 2011/84); D = 15.6–17, H = 7.7–10 (n=2, 2011/85); D = 19.9–20.3, H = 11–11.6 (n=2, 2011/81); D = 21.3, H = 12.1 (n=1, 2011/86).

Differential diagnosis

This species is most similar to G. francoisi. For comparisons, see under that species. Gudeodiscus dautzenbergi is larger, flatter, has wider umbilicus, a weaker apertural lip and the lower end of the anterior lamella is very much elongated anteriorly. Gudeodiscus villedaryi is also flatter and most populations have a keel around the umbilicus and an additional long plica below the parietal lamellae. Gudeodiscus phlyarius is usually flatter, has a wider umbilicus, slimmer peristome and lower callus. Most specimens of G. phlyarius have separated anterior lamella and lower plica, whereas these are always connected in G. giardi giardi. Typical Plectopylis verecunda shells (synonym of G. phlyarius) also have an elevated spire, but their shell shape is rather conical, whereas it is usually domed (rounded) in G. giardi.

Intraspecific diversity

Two subspecies of Gudeodiscus giardi were described from China (see Páll-Gergely and Hunyadi 2013). The populations assigned to the nominotypical subspecies show larger variability in China in terms of shell size, colour and shape, than in Vietnam. In Vietnam G. giardi giardi is moderately variable. Most variability is observable in the formation of the parietal plicae and lamellae (see Remarks and Figures 13L–U).

Description of the genitalia

One specimen was anatomically examined (see also Remarks). Locality: Cao Bằng Province, Quảng Uyên N, 206–207 cross, 430 m, 22°42.737'N, 106°27.223'E, leg. Hunyadi, A., 16.11.2011. (Figure 28B, 29E, 30D, 32C).

Penis very short, almost ball-like; penis wall conspicuously thickened, its inner surface is characterized by transversal lines at the proximal part and longitudinal pockets in the distal part, arranged in a straight row (Figure 28B); there are some calcareous, claw-like objects in the pockets; the claws have a wide, rounded basal part which is found within the pockets, and the short, hook-like part hangs out of the pockets; the base had a granulated surface, probably to provide a better attachment to wall of the pockets, whereas the tip was smooth (Figure 30D); epiphallus C-shaped, longer than the penis; its inner wall with three longitudinal parallel folds (Figure 29E); penis and epiphallus connected with weak membrane; penial caecum approximately as long as the penis; it has low tubercles on the inner wall and small calcareous rounded granules on each tubercle; retractor muscle attaches on the distal part of the penial caecum; it is longer and wider than the caecum; vas deferens convoluted near the vagina. Vagina very thick and long, it is attached to the body wall with several thin ligaments; one side of the vaginal bulb with very much thickened wall, the other side with thin, almost translucent wall, internally with fine, irregular, reticulated sculpture; inner wall of the distal portion of the vagina with well-developed, rather irregular transversal folds (Figure 32C); gametolytic sac and diverticulum slender, they are nearly the same length.

Radula

See Table 6 and Figures 35A–C.

Distribution

(see Figure 42): Newly-collected material was examined from Cao Bằng Province and the northern part of Lạng Sơn Province. The localities of “Col de Nuages” and “Halong Bay” are probably erroneous. This species is also known from the western part of Guangxi, China (Páll-Gergely and Hunyadi 2013).

Remarks

Plectopylis congesta Gude, 1899 was described without exact locality data. Some shells from populations in southern Cao Bằng and northern Lạng Sơn prefectures (Vn10-69; 2011/84, 2011/83, 2011/82, 2011/85) resemble the holotype of P. congesta on the basis of relatively weak peristome and callus, weak (low) posterior lamella and the anterior lamella which is fused to the upper parietal plica. These populations however, falls within the morphological range of the very variable Gudeodiscus giardi giardi, therefore P. congesta is here synonymised with G. giardi giardi.

The genital anatomy of a Chinese specimen of Gudeodiscus giardi giardi was described by Páll-Gergely and Asami (2014). The only notable difference between the Chinese and Vietnamese specimens is the much longer penis in the Chinese individual. It seems that the long, slender, proximal portion of the penis visible in the Chinese specimen is entirely missing in the Vietnamese one.

Gudeodiscus (Gudeodiscus?) hemmeni Páll-Gergely & Hunyadi, sp. n.

Figures 2C–D, 9F, 11G–J

Type material

2012/61 Sơn La Province, Hà Nội 156 km towards Mộc Châu, left side of the road nr. 6, rocky wall, 1110 m, 20°45.993'N, 104°53.868'E, leg. Hunyadi, A., 06.06.2012., holotype HNHM 97458 (Figure 2C), HA/11 paratypes+4jb (not paratype), PGB/3 paratypes; 2012/62 Sơn La Province, Hà Nội 156 km towards Mộc Châu, right side of the road nr. 6, rocky wall, 1110 m, 20°46.085'N, 104°53.888'E, leg. Hunyadi, A., 06.06.2012., HA/13 paratypes+2jb (not paratypes), PGB/1; Vn12-104 Sơn La Province, right side off road Mộc Châu to Sơn La, 20°52.567'N, 104°35.310'E, leg. Hemmen, Ch., 02.10.2012., HE/1; Vn10-103A Hòa Bình Province, ca. km 156 old road Hà Nội to Sơn La (right side off road), 20°46.000'N, 104°53.885'E, leg. Hemmen, Ch. & J., 15.10.2010., HE/1 (Figure 2D); Vn10-76A Sơn La Province, ca. 32 km from Mộc Châu to Hà Nội (old road), 20°47.351'N, 104°50.063'E, leg. Hemmen, Ch. & J., 02.04.2010., HE/1.

Diagnosis

Shell small, with slightly elevated spire, characteristically shaped aperture having wide upper sinulus and small apertural fold (Figure 9F); parietal wall with two lamellae and horizontal plicae above and below; palatal plicae depressed Z-shaped; free from each other, or connected to each other with a ridge (Figures 11G–J).

Description

Shell very small to small, light brown to chocolate brown, with slightly elevated spire, consists of 5.25–5.5 whorls; suture relatively shallow, especially at the first 3–4 whorls; protoconch (2.25–2.5 whorls) glossy, very finely, regularly ribbed, but the ribs are sometimes hardly visible, they are more prominent at the upper part of the whorls, close to the suture; teleoconch without notable spiral lines, very finely regularly ribbed; sculpture strength equal on ventral and dorsal side; umbilicus narrow and deep; aperture with widened upper part (sinulus), apertural lip whitish, thin, slightly expanded but not reflexed; apertural denticle (fold) always present, very small, free from the callus or connected to it.

Two specimens were opened. Parietal side with a stronger anterior lamella with anteriorly widened lower part, and a slimmer posterior lamella; shorter upper and longer lower horizontal plicae free from the anterior lamella, the lower one a bit extends beyond the anterior lamella in the anterior direction. Palatal side with six plicae; first and last are straight, the others are depressed Z-shaped and are connected with a ridge.

Measurements

(in mm): D = 9.5–10.1, H = 4.3–5.2 (n=5, belonging to different populations).

Differential diagnosis

Gudeodiscus hemmeni sp. n. differs from most G. phlyarius populations by the smaller shell, shorter denticle (fold) in the aperture, thinner apertural lip, the wider and reflexed apertural rim, the wide upper sinus of the aperture, lack of spiral lines in the sculpture and narrower umbilicus. Gudeodiscus anceyi is usually smaller, has a longer apertural fold, prominent spiral sculpture, a weaker callus and differently shaped aperture.

In all localities, Gudeodiscus hemmeni sp. n. lives sympatrically with G. messageri raheemi ssp. n., which is much larger, lacks the apertural fold, and usually has an anterior lamella which is dissolved into small denticles.

Intraspecific diversity

Low; shell characters are stable, although only a few shells are known.

Etymology

The new species is dedicated to Jens Hemmen (1944–2012), malacologist and much-valued friend, who contributed to our revision by providing shell and ethanol-preserved material.

Type locality

Sơn La Province, Hà Nội 156 km towards Mộc Châu, left side of the road nr. 6, rocky wall, 1110 m, 20°45.993'N, 104°53.868'E.

Distribution

(see Figure 43). The new species is known from few locations in south-eastern Sơn La province.

Gudeodiscus (Gudeodiscus?) infralevis (Gude, 1908)

Figures 3D–E, 15A–D

1908 Plectopylis infralevis Gude, Journal de Conchyliologie, 55: 345, 350, 352–353., Figs 3a–e, Plate 7, Figs 4–6. [“Quang Huyen”].

1908 Plectopylis soror Gude, syn. n., Journal de Conchyliologie, 55: 355–357., Figs 5a–e, Plate 7, Figs 10–12. [“Quang Huyen”].

2013 Gudeodiscus infralevis, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus soror, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Tonkin, Quang-Huyen, leg. Mansuy, MNHN 24604 (holotype of infralevis, Figure 3D); Tonkin, Quang-Huyen, leg. Mansuy, MNHN 24585 (holotype of soror, Figure 3E).

Diagnosis

Shell small, solid, discoid, with elevated spire, relatively deep umbilicus; relatively thin apertural lip and rather parallel, thick, straight palatal plicae. See also under remarks.

Measurements

(in mm): D = 13.9, D = 6.7 (soror holotype); D = 13.5, H = 6.6 (infralevis holotype).

Differential diagnosis

Our knowledge on the intraspecific variety of the species is very limited (see Remarks). It seems that the thick, rather horizontal palatal plicae, the strong basal sculpture and the elevated spire distinguishes the species from the similar species (Gudeodiscus eroessi, G. multispira, G. soosi, G. yunnanensis, G. cyrtochilus and G. fischeri). The shell and aperture shape suggest that the closest relatives are G. fischeri and G. suprafilaris (see comparisons under those species).

Intraspecific diversity

Plectopylis infralevis and P. soror are considered as conspecific (see Remarks). Only the holotypes of these taxa are known, therefore our knowledge on the intraspecific variability is limited.

Distribution

The type specimens of Plectopylis infralevis and P. soror (synonym of infralevis) were collected in Quang Huyen (Quảng Uyên) (see Figure 39).

Remarks

Only the holotypes of Plectopylis infralevis and P. soror are known. The notable differences between these two shells are the stronger sculpture, slightly shouldered body whorl and small apertural fold in soror. Additionally, there are three lamellae in infralevis versus only one in soror. The three vertical lamellae in the holotype of infralevis is possibly the result of abnormal development. No other species of Plectopylidae has three lamellae. Similar abnormal shells have been reported in Gudeodiscus giardi (see Gude 1908). Consequently, we do not know what the characteristic type of parietal lamellae in this species is (=one or two). The differences between the two specimens suggest only intraspecific variance. Unfortunately we have no freshly-collected material of these two forms, but because of the high similarity between the two holotypes and same type locality we here synonymise soror with infralevis. These two names were published in the same paper (Gude 1908), but infralevis was described earlier in terms of page numbers.

Gudeodiscus (Gudeodiscus) messageri (Gude, 1909)

Diagnosis

Shell small to medium-sized, with slightly elevated spire, dorsal surface somewhat domed; aperture almost circular, apertural fold missing; callus rather blunt and only slightly curved. Parietal wall with two lamellae (the anterior lamella may be dissolved into small denticles); lower parietal plica free or connected to the anterior lamella; palatal plicae oblique, or depressed Z-shaped, usually in contact with each other.

Differential diagnosis

See under the two subspecies.

Gudeodiscus (Gudeodiscus) messageri messageri (Gude, 1909)

Figures 5F–G, 9E, 12N–Q

1909 Plectopylis messageri Gude, Proceedings of the Malacological Society of London, 8: 214–215., Plate 9, Figs 4, 4a–b [“Moung-Hum”, “Nat-Son, Pac-Kha, and Trinh-Tuong”].

2013 Gudeodiscus messageri, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde 142 (1): 8.

Types examined

Tonkin, Muong-Hum, leg. Messager, NHMUK 1922.8.29.53 (holotype of Plectopylis messageri, Figure 5F), Tonkin, Nat-Son, leg. Messager, NHMUK 1922.8.29.54 (holotype of messageri var. minor, Figure 5G).

Museum material examined

Tonkin, coll. Dosch ex Rolle ex Messager, SMF 172088/4; Tonkin, coll. Dosch ex Rolle, SMF 172076/2; Tonkin, Trinh-Tuong, coll. Dosch ex Rolle, SMF 172086/4; Tonkin, Drinch-Tuom (Trinh-Thuong?), coll. Jaeckel ex Messager, SMF 207675/3; Tonkin, alw. Müller, coll. Kaltenbach, SMF 294867/2; Tonkin, Gia-Phu, coll. Dosch ex Rolle, SMF 172089/4; Tonkin, Muong-Bo, coll. Dosch ex Rolle, SMF 172087/4; Tonkin, Muong-Kong, coll. Pfeiffer, K. L. ex Naschloss (?) ex Rolle, January 1938, SMF 102820/1; Tonkin, coll. Dosch ex Rolle ex Messager, SMF 182088/4; Tonkin, Ba-Nat (?), NHMSB 131/200, 122812-122813/2; Pakhé, leg. Messager, MNHN-IM-2012-2129/9; Muong-Hum, leg. Messager, MNHN-IM-2012-2134/15; Nat-Son, Trinh-Thuong, leg. Messager, MNHN-IM-2012-2136/16 („var. minor“); Muong-Kong, leg. Messager, MNHN-IM-2012-2137/4; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2142/2+4jb; Muong-Hum, leg. Messager, MNHN-IM-2012-2131/5; Muong-Hum, leg. Messager, MNHN-IM-2012-2143/3; Muong-Hum, leg. Messager, MNHN-IM-2012-2145/74; Pakhé, leg. Messager, MNHN-IM-2012-2149/1; Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2151/10; Nat-Son, leg. Messager, MNHN-IM-2012-2154/6; Muong-Kong, leg. Messager, MNHN-IM-2012-2159/1; Nat-Son, leg. Messager, MNHN-IM-2012-2162/29; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2163/20; Nat-Son, leg. Messager, MNHN-IM-2012-2165/8+25jb; Bac-Kan, leg. Messager, MNHN-IM-2012-2166/6; Bac-Kan, leg. Messager, MNHN-IM-2012-2172/4; Muong-Hum, leg. Messager, MNHN-IM-2012-2173/3; Muong-Hum, leg. Messager, MNHN-IM-2012-2183/4; Pakhé, leg. Messager, MNHN-IM-2012-2184/1; Long-Ping, leg. Messager, MNHN-IM-2012-2186/8; Muong-Hum, leg. Messager, MNHN-IM-2012-2188/8; Bac-Kan, leg. Messager, MNHN-IM-2012-2194/3; Muong-Hum, leg. Messager, MNHN-IM-2012-2196/4; Nat-Son, leg. Messager, MNHN-IM-2012-2198/2; Nat-Son, leg. Messager, MNHN-IM-2012-2199/2; Tonkin, leg. Messager, MNHN-IM-2012-2202/1; Trinh Thuong, leg. Messager, MNHN-IM-2012-2205/12; Muong-Kong, leg. Messager, MNHN-IM-2012-2479/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2475/10; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2472/16; Cao-Bang, leg. Messager, MNHN-IM-2012-2471/1; Tonkin, Pakhé, leg. Messager, MNHN-IM-2012-2458/7; Long-Ping, leg. Messager, MNHN-IM-2012-2457/23; label not readable, leg. Messager, MNHN-IM-2012-2449/2; Bac-Kan, leg. Messager, MNHN-IM-2012-2403/1; Trinh-Thuong, coll. Levazzari, 1929, MNHN-IM-2012-2408/9; Tonkin, coll. Staadt, 1969, MNHN-IM-2012-2411/3; Nat-Son, coll. Letellier, 1949, MNHN-IM-2012-2414/2; Pac-Kha, coll. Letellier, 1949, MNHN-IM-2012-2415/2; Gia-Phu, MNHN-IM-2012-2418/3; Trinh-Thuong, coll. Lavezzari, 1929, MNHN-IM-2012-2419/10; Tonkin, leg. Messager, MNHN-IM-2012-2425/3; Gia-Phu, leg. Messager, MNHN-IM-2012-2215/33; Muong-Hum, leg. Messager, MNHN-IM-2012-2216/3; Long-Ping, leg. Messager, MNHN-IM-2012-2217/9; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2219/12; Col de Nuages, leg. Messager, MNHN-IM-2012-2221/1; Trinh Tuong, leg. Messager, MNHN-IM-2012-2223/2; Tonkin, leg. Messager, MNHN-IM-2012-2225/4; Tonkin, leg. Messager, MNHN-IM-2012-2230/1; Long-Phai, leg. Messager, 1901, MNHN-IM-2012-2237/2; Muang-Kong, leg. Messager, MNHN-IM-2012-2242/3; Nat-Son, coll. Staadt, 1969, MNHN-IM-2012-2282/1; Tonkin, leg. M. Balansa, 1889 July, MNHN-IM-2012-2296/10; Pakhé, leg. Messager, MNHN-IM-2012-2339/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2315/1; Gia-Phu, leg. Messager, MNHN-IM-2012-2364/2; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2379/1; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2394/1; Tonkin, Pac-Kha, NHMUK1916.3.16.15/1; Tonkin, Pac-Kha, coll. Kennard, A.S. ex auct. (Gude), NHMUK 20130620.2/1; Tonkin, Muong-Hum, coll. Biggs, H.E.J. ex Gygngell, 1930, Acc. no. 2258, NHMUK 20130626/2; Tonkin, Gia-Phu, coll. Kennard, A.S. ex auct. (Gude), NHMUK 20130627/2; Tonkin, Muong-Kong, coll. Salisbury ex Beddome, NHMUK 20130628/2; Tonkin, Muong-Kong, 31/3/09, NHMUK 20130629/3; Tonkin, Muong-Hum, 5/1/09, NHMUK 20130630/3; Tonkin, Pac-Kha, 3/11/08, NHMUK 20130631/2 (“var. minor”); Tonkin, 5/1/09, NHMUK 20130632/3; Tonkin, Muong-Hum, coll. Preston, NHMUK 20130633/2; Tonkin, Muong-Bo, 3/11/08, NHMUK 20130634/2 (“var. major”); Tonkin, That-Khé, coll. Salisbury ex Beddome, NHMUK 20130635/1; Tonkin, Muong-Hum, coll. Kennard, NHMUK 20130636/1; Tonkin, Muong-Hum, NHMUK 1909.3.17.29–31/3; Tonkin, Muong-Hum, NHMUK 1916.3.16.16-18/3; Tonkin, Pac-Kha, NHMUK 1909.3.17.32–34/3 (“var. minor”); Tonkin, Pac-Kha, NHMUK 1909.3.17.24–25/2; Tonkin, Muong-Bo, NHMUK 1909.3.17.35–36/2 (“var. major”); Tonkin, Gia-Phee, coll. Rušnov ex Rolle ex Messager, NHMW 92576/1; Tonkin, Trisch-Tuong, coll. Edlauer ex Werner, NHMW 75000/E/7983/2; Tonkin, Muong-Hum, coll. Oberwimmer ex Wagner ex Messager, NHMW 92573/2; Tonkin, Bac-Kan, coll. Oberwimmer, NHMW 71640/O/14028/1; Tonkin, Long-Ping, 3000 m, coll. Oberwimmer ex Wagner ex Messager, NHMW 92572/1; Tonkin, Muong Hum, coll. Rosen ex Messager, NHMW 71640/O/9476/2; Tonkin, Trinh-Tua (?), coll. Rolle, NHMW 92574/2; Tonkin, Ban-Tao, coll. Rušnov ex Blume, NHMW 92575/1; Tonkin, Muong Kong, NHMW 71640/O/46293/2; Tonkin, Nat-Son, coll. Rosen ex Messager, NHMW 71640/O/9477/1; Tonkin, Trisch Tuong, coll. Rušnov ex Rolle ex Messager, NHMW 92578/2; Tonkin, Ban-Lao, coll. Rolle, NHMW 92577/1; Tonkin, Bac-Kan, coll. Oberwimmer, NHMW 92567; Tonkin, Bac-Kan, coll. Oberwimmer, NHMW 103353/1; Tonkin, Nat-Son, coll. Rušnov ex Messager, NHMW 103355/1; Vietnam/132, Lao Cai Province, Cox-Xan, 400 m, leg. Topál & Matskási, 27.11.1971., VA/10.

Diagnosis

At least one shell was opened of every larger samples. Anterior lamella normal (not dissolved into small denticles); lower parietal plica does not extend beyond the anterior lamella in the anterior direction (Figures 12N–Q).

Measurements

(in mm). D = 12.75–18.5 (according to the original description).

Differential diagnosis

Gudeodiscus messageri messageri inhabits northern Vietnam and in many museum samples it is mixed with Plectopylis gouldingi or Plectopylis fallax (synonyms of G. phlyarius). These two forms have flat shells with a sharp and angled callus, and sometimes with an apertural denticle. Also, the aperture of G. messageri is rather rounded, whereas it is rather elongated in those populations of G. phlyarius (Figures 9D: phlyarius, Figure 9E: messageri). This allows G. messageri and G. phlyarius to be distinguished without breaking the shell. The lower parietal plica, which does not extend beyond the anterior lamella in the anterior direction, is characteristic of G. messageri messageri (see also Remarks), but almost always extends in “P. fallax” and “P. gouldingi”. “Plectopylis verecunda” (synonym of G. phlyarius) and typical G. phlyarius always have a strong apertural fold. Moreover, the lower parietal plica of the latter usually extends beyond the anterior lamella in the anterior direction. For comparison with G. messageri raheemi ssp. n., see there.

Intrasubpecific diversity

Low; the shell size, and the relationship between the lower parietal plica and the anterior lamella show some variability (see remarks). The shell and aperture shape are stable characters.

Distribution

(see Figure 43): Only museum material was available for study, which suggested that this species is located along the Chinese (Yunnan) border.

Remarks

In one sample (MNHN-IM-2012-2215) a specimen had longer lower plica which extended beyond the anterior lamella in the anterior direction.

Gudeodiscus (Gudeodiscus) messageri raheemi Páll-Gergely & Hunyadi, ssp. n.

Figures 5D, 5E, 10A, 12R–V, 20, 28E, 29F–G, 31B, 35D–F

Type material

Thanh Hoa Province, Cam Thuy District, Fish Stream, leg. Naggs, F. & Hao, L.V., 13.05.2008., NHMUK 20110370.1–3 (holotype and two paratype); MAA10 Ninh Bình Province, Cúc Phương Nat. Park, path to fairy cave, approximate GPS position: 20°21'N, 105°54'E, leg. Vermeulen, J., coll. Maassen, W.J.M., 10.10.1998., PGB/1 paratype, WM/3 paratypes; MAA1 Thanh Hóa Province, Pù Luông Nat. Park, NW corner of park near Hang village, limestone area near village, 20°31.84'N, 105°04.76'E, coll. Maassen, W.J.M., 19.09.2003., PGB/1 paratype, WM/3 paratypes; MAA9 Thanh Hóa Province, Pù Luông Nat. Park, limestone hill opposite village Naca, 20°26.86'N, 105°11.57'E, coll. Maassen, W.J.M., 20.09.2003. WM/2 paratypes; Vn10-76A Sơn La Province, ca. 32 km from Mộc Châu to Hà Nội (old road), 20°47.351'N, 104°50.063'E, leg. Hemmen, Ch. & J., 07.10.2010., HE/1 paratype, PGB/2 paratypes; same locality data, leg. Hemmen, Ch., 01.10.2012., HE/1 paratype; Vn10-103 Hòa Bình Province, ca. km 156 old road Hà Nội to Sơn La (right side off road), 20°46.000'N, 104°53.885'E, leg. Hemmen, Ch. & J., 15.10.2010., HE/2 paratypes, PGB/1 paratype, and one paratype in ethanol (anatomically examined, Figure 20); 20080509C Nghệ An Province, Pù Mát Nat. Park, Con Cuông Dist., Lục Dạ Commune, Tân Hợp Village, ca 90 m, 18°57.80201'N, 104°54.67774'E, leg. Ohara, K., 09.05.2008., OK/5 paratypes, PGB/2 paratypes; 20071118A Thanh Hóa Province, Trang Village, Bá Thước. (Bee Cave Mt.), Lân Sa Commune, ca 40 m, 20°19.92147'N, 105°12.49178'E, leg. Ohara, K., 2007.11.18., PGB/1 paratype; 20071118B Thanh Hóa Province, Cây Đăng Cave, Lương Ngọc, Cẩm Lương C., (GPS not recorded), leg. Ohara, K., 18.11.2007., PGB/1 paratype; 20071116C Ninh Bình Province, Cúc Phương Nat. Park, Cave of Prehistoric Man, ca 145 m, 20°15.53843'N, 105°42.38950'E, leg. Ohara, K., 16.11.2007., PGB/2 paratypes; Vn10-104B Sơn La Province, right side off road Mộc Châu to Sơn La, 20°52.567'N, 104°35.310'E, leg. Hemmen, Ch., 02.10.2012., HE/7 paratypes; same data, leg. Hemmen, Ch. & J., 08.10.2010., PGB/2 paratypes; same data, leg. Hemmen, Ch. & J., 14.10.2011., HE/17 paratypes; 2011/106 Ninh Bình Province, Cúc Phương Nat. Park, main entrance, 700 m towards Bống Village, 155 m, 20°15.231'N, 105°42.639', leg. Hunyadi, A., 22.11.2011., HA/12 paratypes +1jb (not paratype), PGB/2 paratypes; 2011/108 Ninh Bình Province, Cúc Phương Nat. Park, Ðộng Người Xưa (=Prehistoric Men Cave), around the cave, 20°17.615'N, 105°40.115'E, leg. Hunyadi, A., 23.11.2011., HA/6 paratypes; 2011/113 Thanh Hóa Province, Cẩm Lương, Ðộng Cây Ðăng (cave), around the cave, 60 m, 20°15.128'N, 105°23.404'E, leg. Hunyadi, A., 25.11.2011., HA/6 paratypes +5jb (not paratypes); 2012/10 Nghệ An Province, Con Cuông 20 km towards Anh Sơn, right side of the road, 40 m, 18°58.302'N, 105°00.796'E, leg. Hunyadi, A., 15.05.2012., HA/7 paratypes +11jb (not paratypes); 2012/60 Sơn La Province, Mộc Châu 5 km towards Sơn La, right side of the road nr. 6, 755 m, 20°52.551'N, 104°35.318'E, leg. Hunyadi, A., 06.06.2012., HA/6 paratypes +16jb (not paratypes), PGB/1 paratypes; 2012/61 Sơn La Province, Hà Nội 156 km towards Mộc Châu, left side of the road nr. 6, 1100 m, 20°45.993'N, 104°53.868'E, leg. Hunyadi, A., 06.06.2012., HA/3 paratypes +2jb (not paratypes); 2012/62 Sơn La Province, Hà Nội 156 km towards Mộc Châu, right side of the road nr. 6., rocky wall, 1110 m, 20°46.085'N, 104°53.888'E, leg. Hunyadi, A., 06.06.2012., HA/5 paratypes+2jb (not paratypes), PGB/1 paratype; Vn12-80A Thanh Hóa Province, Cẩm Thạch, opp. Cẩm Lương Fishstream (W Cẩm Thủy), 20°15.234'N, 105°23.530'E, leg. Hemmen, Ch., 08.10.2012., HE/5 paratypes; same data, leg. Hemmen, Ch. & J., 04.04.2010., HE/2 paratypes; Vn11-215 Sơn La Province, ca. 34 km from Mộc Châu to Mai Châu, 20°45.219'N, 104°54.458'E, leg. Hemmen, Ch. & J., 15.10.2011., HE/1 paratype; Vn11-230 Nghệ An Province, ca. 1.2 km left off rd 48, ca 23 km from Thái Hòa to Qùy Châu, 19°24.363'N, 105°26.521'E, leg. Hemmen, Ch. & J., 22.10.2011., HE/1 paratype; Vn12-268 Thanh Hóa Province, km 585 on road 15 Yến Cát to Ngọc Lặc 1 km right off road 15, 19°45.589'N, 105°25.521'E, leg. Hemmen, Ch. & J., 14.04.2012., HE/3 paratype; 20080510A Nghệ An Province, Pù Huống Nature Reserve, Con Coung District, Anh Son, Hoi Son, ca 30 m, 18°57.11872'N, 105°02.63029'E, leg. Ohara, K, Okubo, K & Otani, J. U., Sang, 10.05.2008., 1 paratype in ethanol, anatomically examined.

Diagnosis

Anterior lamella normal or dissolved into small denticles, if normal, the lower plica extends beyond the anterior lamella in the anterior direction (Figures 12R–V).

Description

Shell medium in size, light to dark brown or dark yellowish, sometimes almost flat but usually with slightly elevated spire, consists of 6.25–6.75 whorls; suture relatively shallow; protoconch (2.5–2.75 whorls) glossy, very finely, regularly ribbed; teleoconch very finely, rather irregularly ribbed, spiral lines visible mainly at the dorsal side where sometimes they are as strong as the ribs (resulting in a reticulated surface), in some specimens however hardly any spiral lines are visible; sculpture weaker on the ventral side but within the umbilicus are as strong as on the dorsal side; umbilicus relatively narrow and deep; aperture wide with whitish or light brown, thickened and reflexed apertural rim; callus slightly S-shaped, well-developed, with upper and with or without lower canal between the ends of callus and the apertural lip; apertural fold always missing.

More than ten specimens were opened belonging to different populations. Parietal side with two lamellae and upper and lower horizontal plicae above and below the anterior lamella; the lower plica usually extends beyond the anterior lamella in the anterior direction; in some populations the anterior lamella (or only the upper part of the lamella) is dissolved into several denticles. Palatal wall with six plicae; first and last are short and relatively straight, the four middle plicae are usually depressed Z-shaped and in many cases connected to each other with a ridge.

Measurements

(in mm). D = 12.9–14.4, H = 6.2–7.5 (n=3, Vn10-76); D = 14.2–14.4, H = 6.8–7.9 (n=3, 20071116C); D = 12.1, H = 6 (n=1, Vn11-230); D = 16–17.9, H = 7.3–7.9 (n=3, Vn11-104).

Differential diagnosis

The lower parietal plica extends beyond the anterior lamella in the anterior direction, which is extremely rarely the case in the nominotypical subspecies. The anterior lamella was dissolved into small denticles in many samples, which has never been observed in the nominotypical subspecies (Figures 12N–Q: messageri, 12R–V: raheemi ssp. n.). The umbilicus of the new subspecies is narrower, it has more rounded whorls and a sharper, more angled callus, than in most samples of Gudeodiscus messageri messageri.

Gudeodiscus messageri raheemi ssp. n. lives sympatrically with an atypical form of G. phlyarius in Ninh Bình Province (see under G. phlyarius). Gudeodiscus phlyarius is flat and has an apertural fold, whereas G. messageri raheemi ssp. n. has somewhat elevated spire and always lacks the apertural fold. See also under G. hemmeni sp. n.

Intrasubspecific diversity

Relatively variable; the colour, spire height, size and morphology of the palatal and parietal lamellae and plicae show considerable variability (see Table 8).

Diversity of shell characters within Gudeodiscus (Gudeodiscus) messageri raheemi ssp. n.

code shell colour spire anterior lamella lower plica shells opened
20071118B yellow very slightly elevated dissolved reaches lamella 1
2012/62 dark yellow slightly elevated normal or dissolved exctends lamella 2
20080509C yellowish-corneous slightly elevated normal exctends lamella 1
2007.11.16C= 2011/106 dark yellow very slightly elevated dissolved exctends lamella 2
Vn12-104= Vn10-103, 2012/60 light or dark brown slightly elevated normal or dissolved reaches or exctends lamella 4
20071118A dark brown slightly elevated dissolved exctends lamella 1
Vn10-76 dark brown slightly elevated dissolved or with buttresses reaches or almost reaches lamella 1
MAA1 yellowish-corneous slightly elevated dissolved reaches lamella 1

Description of the genitalia

Two specimens were anatomically examined. Both specimens had embryos developing in their uterus. Localities: “Specimen1”, Hòa Bình Province, ca. km 156 old road Hà Nội to Sơn La (right side off road), 20°46.000'N, 104°53.885'E, leg. Hemmen, Ch. & J., 15.10.2010. (with 3 embryos, Figures 20, 29F, 31B, 35D–F); “Specimen2”, Nghệ An Province, Pù Huống Nature Reserve, Con Coung District, Anh Son, Hoi Son, ca 30 m, 18°57.11872'N, 105°02.63029'E, leg. Ohara, K, Okubo, K & Otani, J. U., Sang, 10.05.2008. (Figures 28E, 29G).

Penis relatively short and slim, attached to the slightly shorter epiphallus by weak fibres; penis internally with longitudinal folds; the folds are more elevated in the distal part of the penis and they from characteristic “pockets” (Figure 28E); the pockets are arranged in two rows, the upper row (closer the distal end of the penis) is slightly curved on the opened penial wall, but the lower row follows a a wavy line with two peaks; epiphallus have longitudinal folds on the inner wall; penial caecum long; “Specimen1” had two times longer caecum than “Specimen2”; internally with small hollows arranged in longitudinal lines (Figure 29F); “Specimen2” had a few elongated and globular calcareous granules within the hollows (Figure 29G); retractor muscle very long and slim, attaches on the distal end of the penial caecum; vas deferens very long. Vagina extremely long, cylindrical in “Specimen1” and with well-developed vaginal bulb in “Specimen2”; inner wall of the vagina with 6–8 low, parallel or converging folds (Figure 31B); gametolytic sac and diverticulum of the same length, both relatively slim, although the gametolytic sac is a bit swollen.

Radula

See Table 6 and Figures 35D–F.

Etymology

The new subspecies is dedicated to and named after our colleague and much-valued friend, Dinarzarde Raheem.

Type locality

Thanh Hoa Province, Cam Thuy District.

Distribution

(see Figure 43). The new subspecies is known from several localities in Ninh Bình, Thanh Hóa, Sơn La, Hòa Bình and Nghệ An provinces.

Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887)

Figures 4A–F, 5A–C, 9C–D, 10C–F, 11K–X, 12A–M, 21, 22, 28A, 28C, 31C, 35J–L

1887a Plectopylis phlyaria Mabille, Molluscorum Tonkinorum diagnoses: 6. [type locality not specified].

1887b Plectopylis phlyaria. Mabille, Bulletin de le Société Malacologique de France, 4: 100–101., Plate 2, Figs 1–3.

1893 Plectopylis phlyaria, — Pilsbry, Manual of Conchology..., 2(8): 158, Plate 43, Figs 40–42.

1897b Plectopylis phlyaria, — Gude, Science Gossip, 4: 139., Figs 61a–b. [“Tonkin”].

1899c Plectopylis (Endoplon) phlyaria, — Gude, Science Gossip, 4: 148.

1899d Plectopylis (Endoplon) phlyaria, — Gude, Science Gossip, 6: 175.

1901c Plectopylis (Endoplon) phylaria, — Gude, Journal of Malacology, 8: 113–115., Figs 3a–f. [“Than Moi”].

1901c Plectopylis (Endoplon) moellendorffi Gude, Journal of Malacology, 8: 115–116., Figs 4a–f. [“Than-Moi”].

1909 Plectopylis gouldingi Gude, syn. n., Proceedings of the Malacological Society of London, 8: 215, 217., Plate 9, Figs 1, 1a–b. [“Nat-Son”].

1909 Plectopylis verecunda Gude, syn. n., Proceedings of the Malacological Society of London, 8: 215, Plate 9, Figs 3, 3a–b. [“Phony-Tho”].

1909 Plectopylis fallax Gude, syn. n., Proceedings of the Malacological Society of London, 8: 217, Plate 9, Figs 6, 6a–b. [“Muong-Bo”].

1909 Plectopylis anterides Gude, syn. n., Proceedings of the Malacological Society of London, 8: 216, Plate 9, Figs 2, 2a–b. [“Pac-Kha”].

2013 Gudeodiscus phlyarius phlyarius (and Plectopylis moellendorffi is synonym), — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 25–28., Figs 31, 61a–b, 63–65, 75 (map) 77a–b, 112–114.

2013 Gudeodiscus fallax, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus gouldingi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus verecundus, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus phlyarius werneri Páll-Gergely in Páll-Gergely & Hunyadi, syn. n., Archiv für Molluskenkunde 142 (1): 13: Figs 32, 28–29, 34: Figs 76a–d.

Types examined

Tonkin, Muong-Bo, leg. Messager, NHMUK 1922.8.29.58 (holotype of fallax, Figure 5C); Tonkin, Nat-Son, leg. Messager, NHMUK 1922.8.29.56 (holotype of gouldingi, Figure 4E); Tonkin, Pac-Kha, NHMUK 1922.8.29.57 (holotype of anterides, Figure 4F); Tonkin, MNHN 24581 (2 syntypes of phlyaria, Figure 4A); Tonkin, Than-Moi, collection Möllendorff ex Fruhstorfer, SMF 150125a (lectotype of moellendorffi, Figure 4B); Tonkin, Than-Moi, collection Möllendorff ex Fruhstorfer, SMF 150125b (paralectotype of moellendorffi); Tonkin, Phony-Tho, leg. Messager, NHMUK 1922.8.29.55 (holotype of verecunda, Figure 5B).

Museum material examined

fallax-like shells. Tonkin, région de Lao Kay, coll. Dosch ex Rolle, SMF 172081/4; Tonkin, Muong-Bo, coll. Dosch ex Rolle, SMF 172077/2; Tonkin, Muong-Kong, coll. Dosch ex Rolle, SMF 172080/4; Muong-Hum, leg. Messager, MNHN-IM-2012-2130/1; Pakhé, leg. Messager, MNHN-IM-2012-2132/19; Pakhé, leg. Messager, MNHN-IM-2012-2135/6; Muong-Kong, leg. Messager, MNHN-IM-2012-2138/2; Muong-Kong, leg. Messager, MNHN-IM-2012-2140/3; Muong-Hum, leg. Messager, MNHN-IM-2012-2144/1; Ban-Lao, leg. Messager, MNHN-IM-2012-2146/28; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2147/29; Pakhé, leg. Messager, MNHN-IM-2012-2148/3 (“var. major”); Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2155/6 (“var. major”); Pac-Kha, leg. Messager, MNHN-IM-2012-2208/3 (“var. major”); Ban-Lao, leg. Messager, MNHN-IM-2012-2150/22; Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2157/19; Muong-Kong, leg. Messager, MNHN-IM-2012-2158/10; Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2160/22; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2161/28; Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2168/14; Muong-Kong, leg. Messager, MNHN-IM-2012-2169/10; Muong-Hum, leg. Messager, MNHN-IM-2012-2174/1; Muong-Bo, leg. Messager, MNHN-IM-2012-2178/8; Pac-Kha, leg. Messager, MNHN-IM-2012-2180/4; Tonkin, leg. Messager, MNHN-IM-2012-2182/20; Muong-Hum, leg. Messager, MNHN-IM-2012-2190/7; Long-Ping, leg. Messager, MNHN-IM-2012-2192/11; Long-Ping, leg. Messager, MNHN-IM-2012-2206/16; Pac-Kha, leg. Messager, MNHN-IM-2012-2209/4; Pac-Kha, leg. Messager, MNHN-IM-2012-2210/2; Muong-Kong, leg. Messager, MNHN-IM-2012-2244/1; Pakhé, leg. Messager, MNHN-IM-2012-2245/9; Cao-Bang, leg. Messager, MNHN-IM-2012-2470/2; Na-Ri, leg. Messager, MNHN-IM-2012-2463/1; Col de Nuages, leg. Messager, MNHN-IM-2012-2451/6; Tonkin, leg. Messager, MNHN-IM-2012-2450/15; Nat-Son, leg. Messager, MNHN-IM-2012-2445/1; Tonkin, leg. Messager, MNHN-IM-2012-2442/2; Bac-Kan, leg. Messager, MNHN-IM-2012-2247/1; Nga-Son, leg. Messager, MNHN-IM-2012-2255/1; Environs de Yen Bai, ex coll. labo. de Géologie de la Sorbonne (entrée 1952), MNHN-IM-2012-2272/1; Pakhé, leg. Messager, MNHN-IM-2012-2340/12; Tonkin, leg. Messager, MNHN-IM-2012-2395/2; Tonkin, leg. Messager, MNHN-IM-2012-2396/2; Muong-Bo, coll. Staadt, 1969, MNHN-IM-2012-2406/4; Tonkin, coll. Letellier, 1949, MNHN-IM-2012-2410/1; Tonkin, coll. Staadt, 1969, MNHN-IM-2012-2412/1; Trinh-Thuong, coll. Staadt, 1969, MNHN-IM-2012-2416/5; Tonkin, coll. Staadt, 1969, MNHN-IM-2012-2420/1; Trinh-Thuong, coll. Lavezzari, 1929, MNHN-IM-2012-2421/10; Tonkin, Pac-Kha, NHMUK 1916.3.16.14/1; Tonkin, Trinh-Thuong, 5/1/09, NHMUK 20130621.1–2/2; Tonkin, Pac-Kha, 14/6/10, NHMUK 20110289/3 (labelled as „anterides“); Tonkin, Pac-Kha, coll. Preston, 3/11/08, NHMUK 20110290/2 (labelled as „moellendorffi“); Tonkin, Muong-Bo, coll. Salisbury ex Beddome, NHMUK 20110291/3 (labelled as „fallax=moellendorffi“); Tonkin, Lao Kay, NHMUK 1920.1.20.15–16/2; Tonkin, Muong-Bo, NHMUK 1909.3.14.18–20/3; Tonkin, Trinh-Thuong, coll. Rosen ex Messager, NHMW 71640/O/9481/1; Tonkin, Haut-Tonkin, Region de Lao-Kay, coll. Rolle, NHMW 92564/2; Tonkin, Muong-Kong, coll. Rušnov ex Rolle ex Messager, NHMW 92565/1; Tonkin, Pac-Kha, NHMW 46226/1; Tonkin, Long-Po (?), coll. Oberwimmer ex Wagner ex Messager, NHMW 92579/1; Tonkin, Muong-Bo, NHMW 46291/2.

gouldingi/anterides-like shells. Pakhé, leg. Messager, MNHN-IM-2012-2133/53; Muong-Kong, leg. Messager, MNHN-IM-2012-2141/14; Na-Ri, leg. Messager, MNHN-IM-2012-2152/8; Nat-Son, leg. Messager, MNHN-IM-2012-2153/118; Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2156/4; Pac-Kha (Pakhé), leg. Messager, MNHN-IM-2012-2164/44; Bac-Kan, leg. Messager, MNHN-IM-2012-2167/29; Muong-Kong, leg. Messager, MNHN-IM-2012-2170/1; Tonkin, leg. Messager, MNHN-IM-2012-2175/8; Tonkin, leg. Messager, MNHN-IM-2012-2176/10; Muong-Bo, leg. Messager, MNHN-IM-2012-2179/1; Nac-Ri, leg. Messager, MNHN-IM-2012-2187/6; Muong-Hum, leg. Messager, MNHN-IM-2012-2189/1; Long-Ping, leg. Messager, MNHN-IM-2012-2193/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2195/18; Long-Ping, leg. Messager, MNHN-IM-2012-2197/4; Pac-Kha, leg. Messager, MNHN-IM-2012-2200/32; Pac-Kha, leg. Messager, MNHN-IM-2012-2201/15; Tonkin, leg. Messager, MNHN-IM-2012-2203/1; Long-Ping, leg. Messager, MNHN-IM-2012-2207/4; Long-Ping, leg. Messager, MNHN-IM-2012-2213/2; Cho-Ra, leg. Messager, MNHN-IM-2012-2478/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2476/2; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2473/6; Bac-Kan, leg. Messager, MNHN-IM-2012-2465/4; Na-Ri, leg. Messager, MNHN-IM-2012-2464/1; Na-Ri, leg. Messager, MNHN-IM-2012-2462/8; Tonkin, leg. Messager, MNHN-IM-2012-2459/1; Pakhé, leg. Messager, MNHN-IM-2012-2454/8; Col de Nuages, leg. Messager, MNHN-IM-2012-2452/15; Nat-Son, leg. Messager, MNHN-IM-2012-2446/1; Col de Nuages, leg. Messager, MNHN-IM-2012-2214/9; Na-Ri, leg. Messager, MNHN-IM-2012-2220/8; Pakhé, leg. Messager, MNHN-IM-2012-2226/5; Tonkin, leg. Messager, MNHN-IM-2012-2228/1; Muang-Kong, leg. Messager, MNHN-IM-2012-2243/7; Nat-Son, leg. Messager, MNHN-IM-2012-2256/12; Phi-Mi, leg. Messager, MNHN-IM-2012-2334/1; Tonkin, leg. Messager, MNHN-IM-2012-2372/3; Muong-Kong, leg. Messager, MNHN-IM-2012-2429/8; Bac-Kan, leg. Messager, MNHN-IM-2012-2433/16; Bac-Kan, leg. Messager, MNHN-IM-2012-2436/1; Tonkin, leg. Messager, MNHN-IM-2012-2422/8; Pakhé, leg. Messager, MNHN-IM-2012-2389/2; Bac-Kan, leg. Messager, MNHN-IM-2012-2404/1; Tonkin, coll. Levazzari, 1929, MNHN-IM-2012-2405/3; Muong-Bo, coll. Staadt, 1969, MNHN-IM-2012-2407/1; Trinh-Thuong, coll. Levazzari, 1929, MNHN-IM-2012-2409/1; Bac-Kan, leg. Messager, MNHN-IM-2012-2438/1; Tonkin, leg. Messager, MNHN-IM-2012-2439/6; Tonkin, Pac-Kha, coll. Kennard, A.S. ex auct. (Gude), NHMUK 20130620/1; Tonkin, Pac-Kha, coll. Salisbury ex Beddome, NHMUK 20110285/1 (“gouldingi var. minor”); Tonkin, Pac-Kha, coll. Preston, 3/11/08, NHMUK 20110286/2; Tonkin, Pac-Kha, coll. Salisbury ex Beddome, NHMUK 20110287/2 (“anterides”); Tonkin, Pac-Kha, coll. Preston, 3/11/08, NHMUK 20110288/2 (“anterides”); Tonkin, Pac-Kha, 1909.3.17.21-23/3 (“anterides”); Tonkin, Long-Ping NHMUK 1916.3.16.3/1 (“anterides”); Tonkin, Pac-Kha, Tonkin, Pac-Kha, NHMUK 1909.3.17.26-28/3; Tonkin, Pac-Kha, coll. Rosen ex Messager, NHMW 71640/O/9478/2; Tonkin, Bac-Kha, coll. Rušnov ex Rolle ex Messager, NHMW 92566/2; Tonkin, Pac-Kha, NHMW 46225/2; Tonkin, Pac-Kha, coll. Wagner ex Messager, NHMW 71640/O/10290/1; Tonkin, Long-Phai, coll. Wagner ex Messager, NHMW 71640/O/10291/1; Tonkin, Pac-Kha, NHMW 92568/1; Tonkin, Pac-Kha, NHMW 46292/2; Tonkin, Bac-Kan, coll. Wagner ex Messager, NHMW 71640/O/10292/1; Tonkin, Bac-Kan, coll. Oberwimmer, NHMW 71640/O/14029/3; Tonkin, Nat-Son, coll. Rušnov ex Messager, NHMW 103354/1.

Mixed” gouldingi/anterides/fallax samples. Bac-Kan, leg. Messager, MNHN-IM-2012-2171/20; Trinh-Thuong, leg. Messager, MNHN-IM-2012-2181/44; Pakhé, leg. Messager, MNHN-IM-2012-2185/31; Muong-Bo, leg. Messager, MNHN-IM-2012-2211/3; Col de Nuages, leg. Messager, MNHN-IM-2012-2218/25; Col de Nuages, leg. Messager, MNHN-IM-2012-2222/15; Tonkin, leg. Messager, MNHN-IM-2012-2224/13; Tonkin, Pac-Kha, coll. Dosch ex Rolle ex Messager, SMF 172079/4.

phlyarius-like shells. Tonkin, Than-Moi, coll. Jetschin, SMF 207669/6; Tonkin, Than-Moi, coll. Möllendorff ex Fruhstorfer, SMF 150126/10; Tonkin, Chuot-Ki (?), coll. Jaeckel, S. H., SMF 207676/1; Tonkin, coll. Ehrmann ex Fruhstorfer, SMF 150127/2; Tonkin, Than-Moi, coll. Dosch ex Rolle, SMF 172092/4; Tonkin, Than-Moi, coll. Dosch ex Rolle, SMF 172091/4; Tonkin, Than-Moi, coll. Dosch ex Rolle, SMF 172093/2; Tonkin, Than-Moi, coll. Ehrmann ex Fruhstorfer, H., SMF 150138/1+1jb; Than-Moi, leg. Messager, MNHN-IM-2012-2212/5; Long-Phai, leg. Messager, 1901, MNHN-IM-2012-2232/1; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2279/4; Tonkin, coll. Weiss, 1901, MNHN-IM-2012-2281/5; Province de Cao Lang, Lang-Son, Ky Lua, coll. Saurin, MNHN-IM-2012-2288/2; Na-Ri, leg. Messager, MNHN-IM-2012-2474/1; Tonkin, leg. Messager, MNHN-IM-2012-2427/3; Tonkin, leg. Messager, MNHN-IM-2012-2431/1; Tonkin, leg. Messager, MNHN-IM-2012-2391/1; Bac-Kan, coll. Staadt, 1969, MNHN-IM-2012-2392/2; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2397/5; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2398/1; Lang-Son, coll. Letellier, 1949, MNHN-IM-2012-2401/1; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2413/8; Tonkin, coll. Denis, 1946, MNHN-IM-2012-2387/4; Tonkin, Pac-Kha, NHMUK 1916.3.16.13/1; Tonkin, coll. Salisbury ex Beddome, NHMUK 20130599/2; Tonkin, Muong-Bo, 3/11/08, NHMUK 20130600/2; Tonkin, 4/11/01/32, NHMUK 20130601/3; Tonkin, Phu Quac Oai, coll. Biggs, H.E.J., Acc. no. 2258, NHMUK 20130602/4; Tonkin, coll. Trechmann, Acc. no. 2176, NHMUK 20130603/2; Tonkin, Than-Moi, leg. Fruhstorfer, H., NHMUK 1901.12.12.206–208/3; Tonkin, „showing immature armature“, coll. Gude, G.K, NHMUK 1916.3.15.3/1; Tonkin, coll. Fruhstorfer, NHMW 40850/2; Tonkin, coll. Rušnov ex Blume, NHMW 92562/2; Tonkin, Than-Moi, NHMW 39292/4; Tonkin, Than-Moi, coll. Klemm, NHMW 79000/K/17483/1; Tonkin, Than-Moi, coll. Rušnov ex Rolle ex Messager, NHMW 92580/2; Tonkin, Than-Moi, coll. Rušnov ex Rolle, NHMW 92581/4; Tonkin, Than-Moi, coll. Rolle, NHMW 71640/O/12301/1; Tonkin, Than-Moi, coll. Edlauer, NHMW 75000/E/38490/3; Tonkin, That-Ké, coll. Oberwimmer, NHMW 71640/O/12300/1; Tonkin, coll. Fruhstorfer, NHMW 40851/1; Tonkin, That-Ke, coll. Oberwimmer, NHMW 92560/2; Tonkin, Bac-Khuon, coll. Rolle, NHMW 50857/1 (mixed sample with giardi).

verecunda-like shells. Phong-Tho, leg. Messager, MNHN-IM-2012-2177/9; Nat-Son, leg. Messager, MNHN-IM-2012-2447/6; Phong-Tho, leg. Messager, MNHN-IM-2012-2443/4; Phong-Tho, leg. Messager, MNHN-IM-2012-2423/4; Lai-Chau, coll. Morlet, MNHN-IM-2012-2424/1; Son-Ma, coll. Fischer, MNHN-IM-2012-2417/1.

New material examined

fallax-like shells. 2011/125 Lào Cai Province, 1.5 km N of Bắc Ngầm cross, valley on the left side of the road, 155 m, 22°24.149'N, 104°14.462'E, leg. Hunyadi, A., 02.12.2011., HA/1; Vn11-187 Lào Cai Province, ca. 3 km SW of Nhà Văn Hóa, 22°25.513'N, 104°12.194'E, leg. Hemmen, Ch. & J., 04.10.2011., HE/21 (+2 specimens in ethanol, one of them anatomically examined, Figures 21, 28A).

phlyarius-like shells. Vn10-53 Lạng Sơn Province, right off rd. 1B Long Đống to Bình Gia, 21°53.938'N, 106°25.605'E, leg. Hemmen, Ch. & J., 20.3.2010., PGB/3; Vn10-48 Lạng Sơn Province, ca. 6 km SE Bắc Sơn (rd. Bắc Sơn to Nga Hải, left off rd), 21°52.422'N, 106°21.508'E, leg. Hemmen, Ch. & J., 19.03.2010., PGB/3; Vn09-24 Cao Bằng Province, ca. 1 km N of Mã Phục (right side off rd. 3), ca. 575 m, 22°43.938'N, 106°20.527'E, leg. Hemmen, Ch. & J., 23.03.2009., HE/1, PGB/3; Vn10-49 Lạng Sơn Province, ca. 16 km SE Bắc Sơn (rd. Bắc Sơn to Nga Hải, left off rd), 21°50.019'N, 106°18.405'E, leg. Hemmen, Ch. & J., 19.03.2010., PGB/2+2jb; Vn09-18 Lạng Sơn Province, ca. 27 km S of Thất Khê, right side off rd. #4 (Lạng Sơn-Thất Khê), ca. 300 m, 22°07.484'N, 106°35.427'E, leg. Hemmen, Ch. & J., 13.10.2009., PGB/7; Vn09-19 Lạng Sơn Province, ca. 25 km S of Thất Khê, right side off rd. #4 (Lạng Sơn-Thất Khê), ca. 220 m, 22°06.477'N, 106°35.356'E, leg. Hemmen, Ch. & J., 13.10.2009., PGB/2; Vn10-129 Lạng Sơn Province, ca. 58.5 km from Thái Nguyên to Bắc Sơn (right side off road), 21°51.166'N, 106°13.003'E, leg. Hemmen, Ch. & J., 22.10.2010., PGB/1; Vn10-56 Lạng Sơn Province, ca. 7 km from Đồng Mỏ to Văn Quan (left off rd #279), no GPS data, approximate GPS position: 21.696000°N, 106.547271°E, leg. Hemmen, Ch. & J., 21.3.2010., PGB/5; Vn09-16 Lạng Sơn Province, Tân Mỹ (N of Lạng Sơn), temple south of the entrance of village, ca. 240 m, 21°58.891'N, 106°40.265'E, leg. Hemmen, Ch. & J., 12.10.2009., PGB/3; Vn10-128 Lạng Sơn Province, ca. 69 km from Thái Nguyên to Bắc Sơn (right side off road), 21°54.270'N, 106°15.801'E, leg. Hemmen, Ch. & J., 22.10.2010., HE/8, PGB/9; Vn11-154 Lạng Sơn Province, km 47, 1 road # 1B between Văn Quan and Bắc Sơn, 21°52.785'N, 106°26.262'E, leg. Hemmen, Ch. & J., 01.04.2011., HE/6 (also in ethanol); Vn11-155 Lạng Sơn Province, ca. 55 km from Bình Gia to Lạng Sơn on road 1B (no GPS data), leg. Hemmen, Ch. & J., 01.04.2011., HE/11; Vn11-156 Lạng Sơn Province, ca. 10.6 km from Bình Gia to Lạng Sơn on road 1B, 21°53.639'N, 106°25.895'E, leg. Hemmen, Ch. & J., 01.04.2011., HE/70 (one of them is sinistral!), (anatomically examined, Figures 22, 28C, 35J–L); Vn11-157 Lạng Sơn Province, ca. km. 50 of road 1B, 10 km to Bình Gia, 21°53.911'N, 106°25.664'E, leg. Hemmen, Ch. & J., 01.04.2011., HE/6 (anatomically examined, see Figure 31C); 2011/65 Lạng Sơn Province, Đồng Mỏ 2.5 km towards Văn Quan, right side of the road, 270 m, 21°40.358'N, 106°34.783'E, leg. Hunyadi, A., 10.11.2011., HA/5; 2011/66 Lạng Sơn Province, Đồng Mỏ 4.5 km towards Văn Quan, left side of the road, 330 m, 21°40.828'N, 106°34.531'E, leg. Hunyadi, A., 10.11.2011., HA/23, PGB/2; 2011/67 Lạng Sơn Province, Đồng Mỏ 6 km towards Văn Quan, left side of the road, 390 m, 21°41.034'N, 106°33.618'E, leg. Hunyadi, A., 10.11.2011., HA/20, PGB/2; 2011/68 Lạng Sơn Province, Đồng Mỏ 7 km towards Văn Quan, Vạn Linh cross., left side of the road, 370 m, 21°41.158'N, 106°33.588'E, leg. Hunyadi, A., 10.11.2011., HA/56, PGB/3; 2011/70 Lạng Sơn Province, Lạng Sơn, NNE side of Núi Vọng Phu, 21°51.183'N, 106°44.950'E, leg. Hunyadi, A., 11.11.2011., HA/3; 2011/72 Lạng Sơn Province, Na Sầm 12 km towards Thất Khê, left side of the road 210 m, 22°07.870'N, 106°35.038'E, leg. Hunyadi, A., 12.11.2011., HA/86, PGB/2; 2011/73 Lạng Sơn Province, Na Sầm 10 km towards Thất Khê, left side of the road, 190 m, 22°07.530'N, 106°35.381'E, leg. Hunyadi, A., 12.11.2011., HA/27, PGB/2; 2011/74 Lạng Sơn Province, Na Sầm 5.5 km towards Thất Khê, right side of the road, 165 m, 22°05.466'N, 106°35.425'E, leg. Hunyadi, A., 12.11.2011., HA/10; 2011/75 Lạng Sơn Province, Tân Mỹ, tunnel 200 m towards Na Sầm, 210 m, 21°59.110'N, 106°40.077'E, leg. Hunyadi, A., 12.11.2011., HA/19, PGB/2; 2011/76 Lạng Sơn Province, northern edge of Chi Lăng, pass next to the tourist path (N of Đồng Bành), 75 m, 21°34.945'N, 106°30.567'E, leg. Hunyadi, A., 13.11.2011., HA/1; 2011/78 Lạng Sơn Province, Đồng Mỏ 7 km towards Chi Lăng, right side of the road, leg. Hunyadi, A., 13.11.2011., HA/1; 2011/79 Lạng Sơn Province, Đồng Mỏ 5.2 km towards Chi Lăng, right side of the road, 40 m, 21°37.215'N, 106°32.538'E, leg. Hunyadi, A., 13.11.2011., HA/1; 2012/37 Lạng Sơn Province, Đồng Mỏ 2.7 km towards Chi Lăng, right side of the old road, cave, 70 m, 21°38.286'N, 106°33.391'E, leg. Hunyadi, A., 25.05.2012., HA/10; 2012/38 Lạng Sơn Province, Đồng Mỏ 4–5 km towards Chi Lăng, right side of the old road, 65 m, 21°37.479'N, 106°32.730'E, leg. Hunyadi, A., 25.05.2012., HA/6; Vn11-159 Lạng Sơn Province, at km 74.8 on road 1B, Đồng Đăng to Thái Nguyên (8 km S Bắc Sơn), 21°54.543'N, 106°17.298'E, leg. Hemmen, Ch. & J., 02.04.2011., HE/1; Vn11-158 Lạng Sơn Province, ca. 7.5 km foad 1B from Bình Gia to Bắc Sơn, 21°53.908'N, 106°25.661'E, leg. Hemmen, Ch. & J., 01.04.2011., HE/1; Vn09-06 Ninh Bình Province, Cúc Phương Nat. Park, ca. half way from Park Headquarters to Thousand Year Old Tree, left path, ca 510 m, 20°21.366'N, 105°35.513'E, leg. Hemmen, Ch. & J., 03.10.2009., HE/2; MAA10 Ninh Bình Province, Cúc Phương Nat. Park, path to fairy cave, 20°21'N, 105°54'E (approximate GPS position), leg. Vermeulen, J., coll. Maassen, W.J.M., 10.10.1998., NHMUK 19991444/2 + one juvenile/broken shell (marked with no. 3 on Figure 43); same data, WM/3; Vn10-41 Thái Nguyên Province, Temple Chùa Hang (ca. 1 km S of Chợ Chu), 21°54.070'N, 105°38.856'E, leg. Hemmen, Ch. & J., 16.03.2010., HE/3 (marked with no.2 on Figure 43).

Diagnosis

The species is very variable in terms of shell characters (spire height, presence/absence of the apertural fold, aperture shape, morphology of the parietal and palatal plicae and lamellae, fine morphology of the periostracum folds) between and within traditionally recognized species which are synonymized here. Therefore, it is impossible to give a general diagnosis.

Measurements

(in mm). D = 19.3–20.2, H = 8.8–9.1 (n=3, “fallax”, MNHN 2012-2155); D = 10.6–11.7, H = 4.5–4.7 (n=4, “gouldingi”, MNHN, IM-2012-2164); D = 13.2–13.4, H = 5.9–6 (n=2, “phlyarius”, Vn10-53); D = 14.7–15.5, H = 7.8–8.5 (n=3, “phlyarius”, Vn09-18); D = 12.4–12.7, H = 5.7–5.8 (n=2, “phlyarius”, MAA10); D = 15.5–17.1, H = 7.7–7.8 (n=2, “phlyarius”, Vn10-56); D = 15.8–16.6, H = 8.8–9 (n=3, verecunda, MNHN 2012-2177). The size range is continuous to from typical anterides/gouldingi to fallax var. major (see Figure 16).

Differential diagnosis

See under Gudeodiscus anceyi, G. emigrans, G. giardi, G. hemmeni sp. n., G. messageri and Halongella fruhstorferi.

Intrasubspecific diversity. Extremely large. Table 9 summarized the conchological differences between newly collected Vietnamese Gudeodiscus phlyarius samples.

Diversity of shell characters within newly collected Vietnamese Gudeodiscus (Gudeodiscus) phlyarius. Abbreviations: OCMA: only corroded material available.

code spire aperture shape periostracal folds
Vn11-187 flat elongated normal
2011/66 slightly elevated rounded pointed
2011/67 flat/slightly elevated rounded pointed
2011/68 slightly elevated rounded pointed
2011/70 slightly elevated rounded OCMA
2011/72 slightly elevated rounded normal
2011/73 slightly elevated rounded OCMA
2011/75 flat/slightly elevated rounded normal
Vn09-16 slightly elevated rounded OCMA
Vn09-18 slightly elevated rounded normal
Vn09-19 slightly elevated/ elevated rounded OCMA
Vn09-24 flat/slightly elevated rounded OCMA
Vn10-128 flat/slightly elevated rounded normal
Vn10-129 slightly elevated rounded normal
Vn10-48 flat/slightly elevated rounded OCMA
Vn10-49 flat/slightly elevated rounded pointed
Vn10-53 flat rounded pointed
Vn10-56 flat/slightly elevated rounded pointed

Description of the genitalia

Typical fallax: Two specimens were anatomically examined. Locality: Lào Cai Province, ca. 3 km SW of Nhà Văn Hóa, 22°25.513'N, 104°12.194'E, leg. Hemmen, Ch. & J., 04.10.2011. (Figures 21, 28A);

Penis rather spindle-shaped, very much thickened in the middle; internally with a fine papillated/reticulated structure (proximal part) which gradually becomes a laterally folded structure with flat calcareous granules between the folds; pockets are arranged in a rather straight line; epiphallus much shorter than penis, thickest at the penis-epiphallus transition, slowly becoming slimmer towards the vas deferens; penis and epiphallus connected with weak muscle fibres; penial caecum absent in one of the specimens and very small in the other; retractor muscle thick, short, inserts on the small penial caecum (or on the penis-epiphallus transition of the other specimen); vas deferens very long; the proximal section curves within a translucent, straight tube, most convolutions occurring proximally to the vaginal bulb, before becoming a solid, thick tube (until the sperm-oviduct). Vagina long, centrally with well-developed vaginal bulb; vaginal bulb thick-walled, internally with fine reticulated sculpture; distal part of the vagina internally with low, dense, transversal folds; gametolytic sac and diverticulum long, of equal length, extending in parallel; gametolytic sac spindle-shaped, diverticulum of equal thickness throughout.

typical phlyarius: Two specimens were anatomically examined, both contained a few embryos at an early developmental state. Localities: Lạng Sơn Province, ca. 10.6 km from Bình Gia to Lạng Sơn on road 1B, 21°53.639'N, 106°25.895'E, leg. Hemmen, Ch. & J., 01.04.2011. (Figures 22, 28C); Lạng Sơn Province, ca. km. 50 of road 1B, 10 km to Bình Gia, 21°53.911'N, 106°25.664'E, leg. Hemmen, Ch. & J., 01.04.2011. (Figure 31C).

Penis spindle-shaped with thickened middle section; internally with elongated folds of various thickness; this internal ribbed surface also continues in the small penial caecum; retractor muscle short, inserts on the penial caecum; epiphallus shorter and much slimmer than the penis; distally the penis and proximal part of epiphallus bound with connective tissue; vas deferens very long, proximally simple, slim, curved centrally and covered with a sheath distally simple and thickened. Vagina long with well-developed central vaginal bulb; internally the proximal part of the bulb is almost smooth; this sculpture changes to parallelly folded structure in distal direction (Figure 31C); the distal part of the vagina is strongly folded; gametolytic sac and diverticulum of equal length, both being relatively short.

Radula

See Table 6 and Figures 35J–L.

Distribution

(see Figure 43). The populations assigned to Gudeodiscus phlyarius inhabit several regions of northern Vietnam (Lạng Sơn, Cao Bằng, Ninh Bình, and along the border region with the Chinese Yunnan Province) and the Chinese Guangxi. A single shell of typical P. fallax Gude, 1909 was collected in southern Yunnan, very close to the Vietnamese border (Honghe Hanizu Yizu Zizhizhou, Hekou Yaozu Zizhixian, Laofanzhai Xiang, Sierqi N 1.5 km towards Laofanzhai, 155 m, 22°44.637'N, 103°53.782'E, leg. Hunyadi, A., 19.03.2011., HA/1).

Remarks

Gudeodiscus phlyarius and taxa of similar appearance are one of the most problematical groups in the Plectopylidae. Gude (1909) described six species (anterides, cyrtochila, fallax, gouldingi, messageri, verecunda) from the border region of northern Vietnam with the Chinese Yunnan Province. One species, Plectopylis cyrtochila differs from the rest of the species by the smooth, lenticular shell and week peristome and callus. Therefore, it is discussed separately, under the name G. cyrtochilus. In face of the obvious similarities between the remaining five species, Plectopylis messageri and P. fallax were only compared with P. moellendorffi, and P. verecunda was compared with P. messageri. The shell characters of P. anterides and P. gouldingi were only compared with each other. Shells having transitional characters were explained by hybrid origin. Gude (1909) mentions that a specimen of messageri from Pac-Kha might be a hybrid with moellendorffi, and another specimen from the same locality was believed to be a hybrid of anterides and gouldingi. The shell characters distinguishing G. messageri and the sympatric species referable to fallax, gouldingi and anterides are stable, therefore G. messageri is handled separately from the rest of the taxa.

In the recent revision of the Chinese members of the family (Páll-Gergely and Hunyadi 2013), Gudeodiscus phlyarius was reported from several localities in Guangxi. Plectopylis moellendorffi Gude, 1901 was synonymized with P. phlyarius. Gudeodiscus phlyarius werneri was described from two nearby localities near Duan city. All other Chinese G. phlyarius populations were assigned to the nominotypical subspecies. Gudeodiscus phlyarius phlyarius populations were listed in two separate groups based on their appearance, namely “phlyarius-like, mainly flat, small form” and “larger, strongly-built shell (transition to werneri)”.

Here we include the following taxa as synonyms of Gudeodiscus phlyarius: anterides Gude, 1909, fallax Gude, 1909, fallax var. major Gude, 1909, gouldingi Gude, 1909, moellendorffi Gude, 1901, verecundus Gude, 1909, werneri Páll-Gergely, 2013. The last taxon was described on the basis of a keel with a light band around the umbilicus, the dissolved anterior lamella, the posteriorly elongated upper and lower ends of the posterior lamella and the parallel, horizontal palatal plicae. All other formerly recognized species (anterides, fallax, gouldingi, moellendorffi, verecundus) have two well-developed lamellae and oblique, usually depressed Z-shaped palatal plica, often with Y-like posterior ends. However, this study revealed that G. phlyarius is a widely distributed, very variable species and at this moment we see no good reason to maintain one of the morphologically distinct forms as a subspecies. Consequently, we synonymize G. phlyarius werneri with G. phlyarius.

According to the original description the anterior lamella of gouldingi is simple whereas that of anterides is “provided with buttresses”. The upper parietal plica is in contact with the anterior lamella in gouldingi, but the lamella is shorter and free in anterides. Both the upper and lower plicae are shorter in anterides. The first palatal plica of anterides has a descending ridge; the same plica is straight in gouldingi. Additionally, the palatal plicae of anterides are not united by a vertical ridge and are more widely spaced than in gouldingi (the drawings in the original description show the reverse). All of the differences mentioned by Gude (1909) are unstable even within a single sample (assumed to be single population). For example, six shells were opened from a sample collected in Nat-Son (leg. Messager, MNHN-IM-2012-2153, containing 118 “gouldingi” shells). The length of the lower horizontal plica varies greatly, but extends beyond the anterior lamella in the anterior direction in every cases. One specimen had buttresses on the anterior lamella. Two specimens possessed an anterior lamella and the upper horizontal plica united, whereas in the case of four specimens this plica was free. Even among the few shells examined by Gude, he found that shells exhibited transitional character states between anterides and gouldingi. Therefore, these forms cannot be handled as separate species.

In the original description of Plectopylis fallax, Gude (1909) compared it only with P. moellendorffi. He did not compare P. fallax either with P. anterides, or with P. gouldingi. Based on the material housed in the NHM and the specimens mentioned in Gude’s (1909) paper, Gude received very few shells from Messager. Examining the type specimens of the above-mentioned taxa revealed that besides the difference in size (typical fallax is larger than anterides and gouldingi), the only distinguishing feature is the simple and free palatal plicae in fallax and the bifurcated and usually connecting plicae of gouldingi (syn: anterides). The palatal plicae are very variable even within the same sample (see Figures 11) and certainly cannot be used to separate these taxa. Larger shells usually have separated palatal plicae and smaller shells tend to have joint palatal plicae. In addition, the characteristic “nautiliform” shape of typical fallax shells is also not a reliable distinguishing feature from Plectopylis gouldingi/anterides as this trait is also variable across gouldingi and fallax samples.

Based on shell size, most of Messager’s samples in the MNHN can be assigned to three forms (approximately 11–13 mm: gouldingi, 14–16 mm: fallax, 19–21 mm: fallax var. major). However, the ranges of shell size overlaps within a few samples (see “mixed” samples under the material) and assigning some of these shells to one of the forms is impossible. The size range from typical gouldingi (11 mm) to fallax var. major (21 mm) shows a clinal variation without interruption (see Figure 16). On the other hand, we found one sample where the shells clearly differ from two separate forms, namely six typical “fallax var. major” (D: 18.9–20 mm) and gouldingi (D: 12.4–13.5) shells. Unfortunately, as in other samples, the collection locality is not exact enough to determine if these specimens were sympatric.

The apertural fold is always present on typical Gudeodiscus phlyarius shells, but can be rudimentary or missing in typical anterides/fallax/gouldingi shells. The edge of the periostracal folds has a pointed structure which seems to occur in a spiralling pattern on the shell of most Vietnamese phlyarius specimens, but these are always missing in fallax and gouldingi specimens (this trait is visible only in fresh shells) (Figures 10C–F). Typical moellendorffi specimens (synonym of phlyarius) possess a somewhat elevated spire, whereas typical anterides/fallax/gouldingi shells are almost always entirely flat. The only shell character found to be stable within typical Vietnamese Plectopylis phlyarius shells and Plectopylis anterides/fallax/gouldingi shells, however, is the rounded aperture in the former and the elongated aperture in the latter (Figures 9C–D). Even this difference is found to be variable in Chinese populations. The populations listed as “transitions to werneri” in Páll-Gergely and Hunyadi (2013) have rather elongated aperture, similar to that of typical Vietnamese fallax shells, but have elevated spire and overall similar shell shape to typical Vietnamese phlyarius. Therefore, we refer to anterides, gouldingi and fallax as synonyms of G. phlyarius.

The genital structure of typical fallax and typical phlyarius differ considerably. Namely, the former lacks the penial caecum or has only a very small one, and has a reticulated inner surface of the penis, whereas the latter has a short penial caecum and its penis has parallel folds on the inner wall. The size of the penial caecum however, may not have a strong taxonomic value because it was found to vary largely within species (e.g. Gudeodiscus multispira, see Páll-Gergely and Asami 2014). The sculpture of the wall of the proximal portion of the penis may have a seasonal variability (see under G. villedaryi and in Discussion).

A sample (MNHN 2012-2177) labelled verecunda, which contained 9 shells from the type locality (Phony-Tho) supports the synonymy of the taxon in relation to gouldingi and fallax, and therefore to Gudeodiscus phlyarius. Seven of the shells were typical verecundus with an elevated spire, a strong apertural fold connected to the callus, and an anterior lamella fused to the lower plica; the plica does not extending beyond the lamella anteriorly (confirmed in 3 shells). The two other shells however, have somewhat lower spires, the apertural fold is not connected to the callus and the lower plica is free from the anterior lamella and extended beyond it anteriorly (one of the two shells was opened). These two shells can be interpreted as transitional forms between verecundus and fallax in terms of spire height, apertural fold and parietal plicae/lamellae morphology. Since transitional forms were found between typical verecunda and fallax shells, P. verecunda can be interpreted as a local form of fallax having elevated spire and fused anterior lamella and lower plica. Therefore, we synonymise Plectopylis verecunda with G. phlyarius.

There are two Vietnamese “forms” of Gudeodiscus phlyarius which differ from all other typical Vietnamese phlyarius shells. One of the morphologically distinct forms inhabits Ninh Bình Province, where we have knowledge of two populations (number 3 on Figure 43). These shells are smaller and comparatively flatter than the usual phlyarius, and have a characteristic “nautiliform” shape, wider umbilicus, with the last whorl leaving the larger part of the penultimate whorl visible. No differences in the lamellae were recognized. The other form is known from one locality in north-western Thái Nguyên Province (number 2 on Figure 43). This has an elevated spire and narrow umbilicus. Only three specimens are known, and two of them were opened. One of the opened specimens had three very weak parietal lamellae (possibly an abnormal character state, similar to that of the holotype of Plectopylis infralevis), and the second has the anterior lamella and the lower plica fused; the plica did not extends beyond the anterior lamella in the anterior direction.

Two Chinese populations (near Baxianyan, number 1 on Figure 43) have an oblique anterior lamella and an aperture more reflected downwards.

Gudeodiscus (Gudeodiscus?) suprafilaris (Gude, 1908)

Figures 9A–B, 9R, 14S–Y

1908 Plectopylis suprafilaris, — Gude, Journal de Conchyliologie, 55: 353–355., Figs 4a–e, Plate 7, Figs 7–9. [“Quang Huyen”].

2013 Gudeodiscus suprafilaris, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Tonkin, Quang-Huyen, leg. Mansuy, MNHN 24586 (holotype?, Figure 9A).

Museum material examined

Nga-Son, leg. Messager, MNHN-IM-2012-2234/2; Nga-Son, leg. Messager, MNHN-IM-2012-2254/3.

New material examined

Vn10-125 Cao Bằng Province, ca 60 km from Cao Bằng to Bảo Lạc (right side off road), 22°39.494'N, 105°51.059'E, leg. Hemmen, Ch. & J., 19.10.2010., PGB/1; 2011/70 Lạng Sơn Province, Lạng Sơn, NNE edge of Vọng Phu Mountain, 21°51.183'N, 106°44.950'E, leg. Hunyadi, A., 11.11.2011., HA/1jb; 2011/81 Cao Bằng Province, Đèo Mã Phục (pass) 500 m towards Quảng Uyên, left side of the road, rock cavern, 610 m, 22°43.981'N, 106°20.333'E, leg. Hunyadi, A., 14.11.2011., HA/73+10jb, PGB/3 (see Figure 9B); 2011/85 Cao Bằng Province, Cao Bằng 34.5 km towards Đông Khê, left side of the road, 500 m, 22°27.487'N, 106°25.047'E, leg. Hunyadi, A., 15.11.2011., HA/4jb; 2012/44 Cao Bằng Province, southern edge of Pắc Rảo, Trùng Khánh 3 km towards Quảng Uyên, left side of the road, 570 m, 22°48.961'N, 106°30.533'E, leg. Hunyadi, A., 28.05.2012., HA/1; Vn10-67 Cao Bằng Province, right off old rd. 4A, ca 29 km from Cao Bằng to Đông Khê, 22°28.737'N, 106°21.767'E, leg. Hemmen, Ch. & J., 26.03.2010., HE/2.

Diagnosis

Shell small, discoid-globular, with weak apertural lip and usually a small denticle in the aperture (Figure 9R). The sudden change of the shell sculpture (reticulated above, smooth below) is very characteristic of this species. For the morphology of the plicae see Remarks and Figures 14S–Y.

Measurements

(in mm). D = 13.1, D = 7.3 (n=1, Vn10-125); D = 11.1–12.1, H = 6.2–6.3 (n=3, 2011/81); D = 12–14.1, H = 6.2–7.2 (n=2, Vn10-67).

Differential diagnosis

The shell shape of Gudeodiscus suprafilaris is similar to that of G. infralevis, but G. suprafilaris has more regular whorls, a more elevated spire and its sculpture changes suddenly from reticulated dorsally to smooth basally on the last whorl. The sudden change of the sculpture and the almost globular shell distinguishes the species from other species (G. eroessi, G. multispira, G. soosi, G. yunnanensis, G. cyrtochilus and G. fischeri). The Chinese G. eroessi hemisculptus Páll-Gergely & Hunyadi, 2013 and G. yanghaoi which have similar sculpture are larger, have a flatter shell and different lamellation.

Intraspecific diversity

The species is very variable in terms of spire height, the formation of parietal and palatal plicae and lamellae, and the extent of the sculptured portion on the dorsal side of the shell. The distinctive aperture shape, minute apertural fold and the unique sculpture render this species distinctive and easy to identify. See also Remarks and Table 10.

Diversity of shell characters within Gudeodiscus (Gudeodiscus?) suprafilaris. Abbreviations: OCMA: only corroded material available.

code spire anterior lamella posterior lamella palatal plicae changing line of the sculpture
type series high short present long, united middle line of the body whorl
2011/81 moderately high long present long, united lower than the middle line of the body whorl
2012/44 moderately high unknown unknown short, free middle line of the body whorl
Vn10-125 high long absent only vertical line visible middle line of the body whorl
Vn10-67 moderately high unknown unknown short, united lower than the middle line of the body whorl
2011/85 high short present short, free lower than the middle line of the body whorl
2011/70 high short present short, free OCMA

Distribution

(see Figure 41). Examined material was from only Cao Bằng and Lạng Sơn Provinces. The type locality (Quang-Huyen) lies in Cao Bằng Province (see Figure 39).

Remarks

The palatal and parietal plicae and lamellae exhibit extreme variability between populations. The holotype exhibits relatively long, horizontal palatal plicae connected with a ridge; the parietal side possesses a well-developed posterior lamella, upper and lower plica, and a reduced, short anterior lamella (Figures 14S–T). The museum specimens we examined (probably from the same sample as the holotype) had similar palatal plicae and also a reduced anterior lamella. Two examples collected close to the type locality (2011/81, see Figures 14U–V and 2012/44) were examined. Shells belonging to both populations had identical palatal plicae to those of the holotype, but in contrast, had a much longer anterior lamella, free from the lower plica or almost united to it. Additionally, in the type series, the sculptured dorsal surface changes to a smooth surface at around the middle line of the body whorl. In contrast, in the two newly-collected samples the change between the two different sculptures occurs lower, closer to the umbilicus.

In a shell from another population (Vn10-125, see Figures 14X–Y) the palatal plicae were greatly reduced in length so that when viewed through the semi-transparent shell, they appear as though only a single vertical plica was present. The parietal wall of the same shell was ornamented by a strong anterior lamella entirely fused with the lower plica; the posterior lamella was absent, its position was indicated only by a very slight elevation within the structure of the shell.

Gudeodiscus (Gudeodiscus) villedaryi (Ancey, 1888)

Figures 8B–D, 9J, 10B, 13V–Y, 23, 24, 28F–G, 30A–C, 30F, 32D, 35M–O

1888 Plectopylis Villedaryi Ancey, Le Naturaliste 2 (10): 71–72., Fig. 2. [“Région de Lang-son et de Bac-ninh”].

1897b Plectopylis villedaryi, — Gude, Science Gossip, 4: 139., Figs 60 a–b. [“Lang-son and Bac-ninh, Tonkin”].

1899a Plectopylis villedaryi, — Gude, Science Gossip, 5: 332.

1899c Plectopylis (Endoplon) villedaryi, — Gude, Science Gossip, 4: 148.

1899d Plectopylis (Endoplon) villedaryi, — Gude, Science Gossip, 6: 175.

1900 Plectopylis Villedaryi, — Gude, The Annals and Magazine of Natural History, 7 (5): 313.

1901c Plectopylis villedaryi, — Gude, Journal of Malacology, 8: 116–117., Figs 5a–e. [“Than-Moi”].

1901 Plectopylis (Endoplon) choanomphala Möllendorff, Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 33 (5/6): 75. [“Than-moi”].

1901c Plectopylis (Endoplon) villedaryi, — Gude, Journal of Malacology, 8: 116–117., Figs 5a–e. [“Than-Moi”].

1905a Plectopylis Villedaryi, — Dautzenberg & Fischer, Journal de Conchyliologie, 53: 93. [“Dong-Trieu, dans les racines des arbustes qui poussent sur des rochers à ceux de la baie d’Along”].

2013 Gudeodiscus villedaryi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Haut-Tonkin, NHMUK 1930.9.12.38 (holotype of villedaryi, Figure 8C); Tonking, Than-Moi, collection Möllendorff ex Fruhstorfer, SMF 9279 (lectotype of choanomphala, Figure 8B); Tonking, Than-Moi, SMF 9276 (paralectotype of choanomphala).

Museum material examined

Tonkin, Nja-Ba-Thà, coll. Dosch ex Rolle, SMF 172084/4; Tonkin, Mui-Cho, SMF 172095/4; Tonkin, Than-Moi, coll. Ehrmann ex Fruhstorfer, SMF 150133/2; Tonkin, Muc Cho Nja Ba, coll. Jaeckel, S. H., SMF 207680/3; Tonkin, Mui Aro Nja Ba Thà, HNHM 9576/1; Than-Moi, coll. Letellier, 1949, MNHN-IM-2012-2306/3; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2321/2; Than-Moi, coll. Staadt, 1969, MNHN-IM-2012-2335/10; Indo-China, coll. Krempf, MNHN-IM-2012-2400/7 juvenile shells; Tonkin, Nju Ba Thá, coll. Rolle, NHMW 50856/2; Tonkin, coll. Fruhstorfer, NHMW 40848/1; Tonkin, Phu-Ty, coll. Edlauer ex Rolle, NHMW 75000/E/7804/2; “China”, coll. Rolle, NHMW 71640/O/12303/1; Tonkin, Moi-Cho-Nja, coll. Rušnov ex Rolle ex Messager, NHMW 92586/2; Tonkin, Than Moi, coll. Edlauer ex Rolle, NHMW 75000/E/7816/3; Tonkin, Nja-Ba-Thá (?), coll. Rušnov ex Blume, NHMW 92584/1; Tonkin, Than-Moi, coll. Rušnov ex Rolle ex Messager, NHMW 92585/1; Tonkin, Than-Moi, coll. Käufel ex Klemm, NHMW 79000/K/17482/2; Tonkin, Cho-Moi, coll. Rolle, NHMW 71640/O/12302/1.

New material examined

Vn10-47A Thái Nguyên Province, ca. 4 km NE of Đình Cả, Phượng Hoàng Cave, 21°46.554'N, 106°07.210'E, leg. Hemmen, Ch. & J., 18.03.2010., PGB/3; 20090520A Thái Nguyên Province, Võ Nhai District, Phú Thượng Commune, Phượng Hoàng Cave, Mỏ Gà Vill., ca 150 m, 21°46.836'N, 106°07.107'E, leg. Ohara, K., 20.05.2009., OK/15, PGB/4 (anatomically examined, Figures 24, 28G, 32D); Vn10-128 Lạng Sơn Province, ca. 69 km from Thái Nguyên to Bắc Sơn (right side off road), 21°54.270'N, 106°15.801'E, leg. Hemmen, Ch. & J., 22.10.2010., PGB/1; 2012/58 Thái Nguyên Province, northern edge of Lâu Thượng, 5 km W of Ðình Cả, 105 m, 21°44.484'N, 106°01.420'E, leg. Hunyadi, A., 04.06.2012., HA/4; 2011/65 Lạng Sơn Province, Đồng Mỏ 2.5 km towards Văn Quan, right side of the road, 270 m, 21°40.358'N, 106°34.783'E, leg. Hunyadi, A., 10.11.2011., HA/7+2jb, PGB/1; 2011/68 Lạng Sơn Province, Đồng Mỏ 7 km towards Văn Quan, Vạn Linh cross., left side of the road, 370 m, 21°41.158'N, 106°33.588'E, leg. Hunyadi, A., 10.11.2011., HA/1; 2011/76 Lạng Sơn Province, northern edge of Chi Lăng, pass next to the tourist path (N of Đồng Bành) 75 m, 21°34.945'N, 106°30.567'E, leg. Hunyadi, A., 13.11.2011., HA/15+1jb, PGB/2; 2011/79 Lạng Sơn Province, Đồng Mỏ 5.2 km towards Chi Lăng, right side of the road, 40 m, 21°37.215'N, 106°32.538'E, leg. Hunyadi, A., 13.11.2011., HA/3; 2011/102 Thái Nguyên Province, Ðình Cả NE 4 km, Phượng Hoàng cave, around the entrance of the cave, 365 m, 21°46.782'N, 106°07.189'E, leg. Hunyadi, A., 13.11.2011., HA/25+2jb, PGB/2 (anatomically examined, Figures 23, 28F, 30A–C, 30F, 35M–O); 2012/38 Lạng Sơn Province, Đồng Mỏ 4–5 km towards Chi Lăng, right side of the old road, 65 m, 21°37.479'N, 106°32.730'E, leg. Hunyadi, A., 25.05.2012., HA/12+1jb; Vn11-159 Lạng Sơn Province, at km 74.8 on road 1B, Đồng Đăng to Thái Nguyên (8 km S Bắc Sơn), 21°54.543'N, 106°17.298'E, leg. Hemmen, Ch. & J., 02.04.2011., HE/1; Vn11-163 Lạng Sơn Province, road 242 from Đình Cả to Hữu Lũng, SE Bình Long, 21°38.424'N, 106°11.761'E, leg. Hemmen, Ch. & J., 02.04.2011., HE/9; Vn11-151 Thái Nguyên Province, ca. 48 km from Thái Nguyên to Bắc Son, near Lâu Thượng (SW Đình Cả), 21°43.522'N, 105°58.662'E, leg. Hemmen, Ch. & J., 29.03.2011., HE/8; Vn11-161 Lạng Sơn Province, at km 90.5 on road 1B Đồng Đăng to Thái Nguyên, 21°49.656'N, 106°12.636'E, leg. Hemmen, Ch. & J., 02.04.2011., HE/1; Vn11-152 Lạng Sơn Province, road 1B, ca. 23 km SE Bắc Sơn (between Đình Cả and Bắc Sơn), 21°49.155'N, 106°11.448'E, leg. Hemmen, Ch. & J, 29.03.2011., HE/3.

Diagnosis

Shell medium-sized to large, strongly-built, nearly smooth, with thick apertural lip and an oblique, strong apertural fold (Figure 9J); umbilicus frequently keeled. The anterior parietal lamella is supported by an anteriorly elongated lower plica; an additional, long horizontal plica is present near the lower suture; middle palatal plicae oblique (Figures 13V–Y).

Measurements

(in mm): D = 19.5–21.7, H = 11–12.6 (n=4, Vn11-163); D = 15.4–18.4, H = 7.8–8.9 (n=3, Vn11-151); D = 21–23.4, H = 11.3–12.6 (n=3, Vn11-152); D = 15.4–16.5, H = 8.4–9.5 (n=3, 20090520A); D = 16.7–20.6, H = 8.9–9.8 (n=3, Vn10-42); D = 16.1–17.8, H = 7.9–9.2 (n=2, Vn10-44).

Differential diagnosis

See under Gudeodiscus dautzenbergi and Halongella schlumbergeri.

Intraspecific diversity

The morphology of palatal and parietal plicae and lamellae do not show significant variation. Conversely, shell size, aperture shape, shape of the dorsal side of the shell, spire height and the presence or absence of the periumbilical keel show considerable variation across populations. See also Table 11.

Diversity of the periumbilical region within Gudeodiscus (Gudeodiscus) villedaryi.

code keel
2012/58 absent
2011/65 present
2011/68 present
2011/76 present
2011/79=2012/38 present
2011/102= Vn10-47=20090520A present
Vn10-128 slight keel
Vn11-159 slight keel
Vn11-151 slight keel
Vn11-152 absent
Vn11-161 slight keel
Vn11-163 present

Description of the genitalia

Three specimens were anatomically examined; they were collected at the same locality at different times of the year (20090520A: 20 May, two specimens; 2011/102: 12 November, one specimen). One of the specimens from the 20090520A sample had abnormally developed genitalia. Namely, the penis was “normally” connected to the genital opening, but the vagina was only attached to the atrium area with weak fibres. Nevertheless, the gametolytic sac was filled with fragments of a spermatophore which is an indication of successful mating. An epiphallus was absent and the vas deferens started from the base of the vagina. The other specimen from the 20090520A sample (collected in May) had 18 embryos developed in its uterus, and had no claws between the folds on the inner wall of the penis, whereas the one collected in November was not gravid, but had several claws within the folds inside the penis. The claws had a moderately long base inside the pockets, whereas their hook-like tip was hanging out of the pockets. The SEM images revealed that the base had a granulated surface, probably to provide a better attachment to wall of the pockets, whereas the tip was smooth. Additionally, the specimen from November had parallel, dense, wavy, horizontal folds on the inner wall of the proximal part of the penis, and longitudinal, parallel folds on the distal portion of the penis. The other specimen sampled in May had only a slightly waved proximal part of the longitudinal folds. Other parts of the genitalia did not differ between the two specimens.

The penis is short, pear-shaped internally with pockets standing in a straight row at the distal part of the penis; the epiphallus is much more slender, and is somewhat shorter than the penis; there is no penial caecum, the retractor muscle attaches on the apical part of the penis (at the penis-epiphallus transition); epiphallus approximately as long as the penis, it transforms to vas deferens without obvious boundary; epiphallus internally with parallel folds; vagina long with a well-developed vaginal bulb, it is attached to the body wall with several ligaments; vaginal bulb with thickened wall, internally almost smooth, only with hardly visible longitudinal folds; inner wall of the distal part of the vaginal with low, parallel or converging, serrulate folds (Figure 32D); there is a shorter, thicker gametolytic sac and a longer, more slender diverticulum.

Radula

See Table 6 and Figures 35M–O.

Distribution

(see Figure 40). The species is known from Thái Nguyên and Lạng Sơn provinces.

Remarks

Gudeodiscus villedaryi is a very variable species in terms of shell characters. The species is recognised on the basis of the presence of an additional lower plica, which is absent in G. dautzenbergi. The latter species might be only a variety of G. villedaryi which has lost the lower plica. More information is needed to determine whether the populations assigned to G. villedaryi and G. dautzenbergi form monophyletic groups. See also under G. dautzenbergi.

Veludiscus Páll-Gergely, subgen. n.

Type species

Gudeodiscus eroessi Páll-Gergely & Hunyadi, 2013.

Diagnosis

Shell indistinguishable from those of the subgenus Gudeodiscus (Gudeodiscus) and the genus Halongella gen. n. Anatomy: Epiphallus is slender, cylindrical; retractor muscle inserts on the distal end of the penial caecum, but the whole caecum is covered by additional, fine muscle fibres which insert on the distal end of the penis. Radula: central tooth smaller than the ectocone of the first lateral; mesocone of the first lateral is usually wide, rhomboid. Marginals bi- or tricuspid, with blunt inner cusp and shallow incision between the inner two cusps. See drawings and descriptions of the genital anatomy in Páll-Gergely and Hunyadi (2013) and Páll-Gergely and Asami (2014).

Content

emigrans (Möllendorff, 1901), eroessi Páll-Gergely & Hunyadi, 2013, goliath Páll-Gergely & Hunyadi, 2013(?), okuboi Páll-Gergely & Hunyadi, 2013, pulvinaris (Gould, 1859).

Etymology

The name Veludiscus is composed of two Latin words. Velum (=curtain, sail, covering) refers to the characteristic feature of the genitalia, namely the additional curtain-like muscle covering the penial caecum and the retractor muscle, and discus (=disc) refers to the shape of the shell. The genus is gender masculine.

Remarks

Some conchologically similar species may belong to this subgenus, especially those which inhabit similar geographic regions. Future investigations on the anatomy and radula morphology of Gudeodiscus species should clarify the subgeneric status of the taxa with unknown anatomy.

Gudeodiscus (Veludiscus) emigrans (Möllendorff, 1901)

Diagnosis

A medium-sized to large species with dense, fine riblets; shell flat, callus always, apertural fold usually present. Parietal wall with C-shaped posterior lamella; anterior lamella (if present) slightly S-shaped; if anterior lamella is missing; one lower plica or four parallel plicae are visible in front of the lamella; palatal wall with almost straight, slightly oblique, depressed Z-shaped or Y-shaped plicae (Figures 13A–D).

Differential diagnosis

Gudeodiscus phlyarius has stronger apertural fold, a straight anterior parietal lamella (in the Chinese populations assigned to G. phlyarius werneri Páll-Gergely, 2013 = synonym of phlyarius, sometimes dissolved into small denticles) and usually a somewhat elevated spire. Gudeodiscus messageri, G. hemmeni sp. n. and G. anceyi have two parietal lamellae or several small denticles standing in a line at the position of the first lamella.

General distribution

The three subspecies of G. emigrans are known from northern Vietnam and northern Guangxi.

Gudeodiscus (Veludiscus) emigrans emigrans (Möllendorff, 1901)

Figures 6E, 13A–B

1901 Plectopylis (Sinicola) emigrans Möllendorff, Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 33 (5/6): 75, 76. [“Mansongebirge”]

2013 Gudeodiscus emigrans emigrans, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 12., Figs 24, 44a–b, 58 (map).

Material examined

See Páll-Gergely and Hunyadi (2013).

Diagnosis

Spiral sculpture missing or not conspicuous, parietal wall with one lamella and a short lower parietal plica anterior to the lamella.

Measurements

(in mm). D = 17.3, H = 7.5 (holotype).

Differential diagnosis

Gudeodiscus emigrans emigrans has weaker spiral sculpture than G. emigrans quadrilamellatus, and has only one horizontal parietal plica anterior to the lamella (close to the lower suture), whereas G. emigrans quadrilamellatus has four parallel horizontal plicae. The Chinese G. emigrans otanii has Y-shaped palatal plicae (these are simple in the nominotypical subspecies and in G. emigrans quadrilamellatus). Moreover, some specimens of G. emigrans otanii have two vertical lamellae (see Páll-Gergely and Asami 2014).

Intrasubspecific diversity

Very few shells are known from museum collections. The subspecies is easily recognisable, but more material is needed to understand the intrasubspecific diversity.

Distribution

Plectopylis (Sinicola) emigrans was described from the “Manson-Gebirge” = “Mau Son Mts, about 30 km E of Lang Son” (Schileyko 2011) (see Figure 39).

Gudeodiscus (Veludiscus) emigrans quadrilamellatus Páll-Gergely, 2013

Figures 6F, 13C–D

1901a Plectopylis emigrans Gude, Journal de Conchyliologie, 49: 206–208. Plate 6., Figs 5a–c. [“Bac Kan, secteur de Nac Ri, Baie d’Along”].

2013 Gudeodiscus emigrans quadrilamellatus Páll-Gergely in Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 15–17., Figs 27, 45a–b, 58 (map).

Material examined

Samples not mentioned in Páll-Gergely and Hunyadi (2013) are the following: Hạ Long Bay, leg. Messager, MNHN-IM-2012-2320/1; Indochine, leg. Messager, MNHN-IM-2012-2455/2; Tonkin, coll. Letellier 1949, MNHN-IM-2012-2448/1.

Diagnosis

Spiral sculpture conspicuous, parietal wall with one lamella and four parallel horizontal plicae in front of the single lamella.

Measurements

(in mm): D = 17.7–18.6, H = 7.1–7.6 (n=3, sample from the type locality).

Differential diagnosis

See under Gudeodiscus emigrans emigrans.

Intrasubpecific diversity

Low; shell characters are stable. The subspecies is easily recognisable and can be separated from other Vietnamese and Chinese taxa without problems.

Distribution

(see Figure 42): Gudeodiscus emigrans quadrilamellatus is known from Bắc Kạn and Tuyên Quang Provinces. Museum samples are labelled from Tam Đảo, on the border region of Thái Nguyên and Vĩnh Phúc Provinces (Au Nord de Ha Noi, Tam Dao, MNHN-IM-2012-2123/3). Records from the Hạ Long area (e.g. Gude 1901a) are probably incorrect (see also Páll-Gergely and Hunyadi 2013).

Halongella Páll-Gergely, gen. n.

Type species

Helix (Plectopylis) Schlumbergeri Morlet, 1886.

Diagnosis

Shells do not differ from those of Gudeodiscus; small to very large, body whorl rounded, callus and apertural fold; Parietal wall with two lamellae or the anterior one is reduced or absent; parietal side with straight, slightly curved, or depressed Z-shaped plicae.

Penial caecum absent. Penis internally with longitudinal, parallel folds, with tiny, flat, T-shaped calcareous granules between the folds, all along the penis; there are no determined “pockets” for the granules at the apical part of the penis. Epiphallus internally with longitudinal folds having several perpendicular projections which overlap with those of the neighbouring fold. Radula similar to Gudeodiscus (Veludiscus) subgen. n. by the smaller central tooth than the ectocone of the first laterals and the marginals which are bicuspid or tricuspid with blunt innermost cups and shallow incision between the two inner cusps.

Differential diagnosis

Sinicola species have a keeled body whorl, whereas it is rounded in Halongella gen. n. Moreover, all Sinicola species have a penial caecum, a central tooth which is as large as or larger than the ectocone of the first laterals and clearly tricuspid marginals with deep incision between the innermost two, sharp cusps. The same radular morphology has been observed in Sicradiscus species. Additionally, “eastern” Sicradiscus species possess keeled shells, whereas the rounded shelled “western” species of the genus have determined pockets on the inner penial wall, similar to that of Gudeodiscus. For comparison with Gudeodiscus, see there.

Included taxa

fruhstorferi Möllendorff, 1901 and schlumbergeri Morlet, 1886.

Etymology

This generic name derives from the name of the Halong Bay, where both species occur. The genus is gender feminine.

Remarks

Calcareous granules of complicated shape have been found in the vagina of Halongella schlumbergeri, and some granules not having characteristic shapes have been found in the vaginal lumen of H. fruhstorferi. The taxonomic value of these granules are unknown. No granules of characteristic shape have been found in the vaginas of Gudeodiscus species, therefore this can be a synapomorphy of Halongella gen. n.

Halongella fruhstorferi (Möllendorff, 1901)

Figures 7D, 9O, 14O–R, 25, 29C, 29I, 32A–B, 36A–C

1901 Plectopylis (Sinicola) fruhstorferi Möllendorff, Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 33(5/6): 114–115. [no locality specified].

1901c Plectopylis (Sinicola) fruhstorferi, — Gude, Journal of Malacology, 8: 112–113., Figs 2a–e. [“Kebao”].

1915 Plectopylis fruhstorferi, — Gude, Records of the Indian Museum, 8: 513.

2013 Gudeodiscus fruhstorferi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Tonkin, Kebao, collection Möllendorff ex Fruhstorfer 128, SMF 9258 (lectotype); Tonkin, Kebao, collection Möllendorff ex Fruhstorfer 128, SMF 9259 (paralectotype).

Museum material examined

Tonkin, Kebao (Insel), SMF 150081/2; Kebao, leg. Fruhstorfer, 29.10.1900, RBINS/2; Kebao, coll. Rolle, NHMUK 20110239/2; Kebao, NHMUK 1901.12.23.41–43/3; Tonkin, NHMUK 1916.3.16.9/1.

New material examined

Vn11-171 Quảng Ninh Province, Vân Đồn Island (NE Cẩm Phả), Cái Rồng village, 21°3.560'N, 107°25.551'E, leg. Hemmen, Ch. & J., 14.08.2011., HE/23, HA/1, PGB/3 (anatomically examined, Figures 25, 29C, 29I, 32A–B, 36A–C).

Diagnosis

Shell small, solid, thin-walled, almost flat and smooth, with weak apertural lip and sometimes a small apertural denticle (Figure 9O). Parietal wall with one parietal lamella with two short horizontal plicae anteriorly, one above and one below; palatal plicae short, oblique, depressed Z-shaped (Figures 14O–R).

Measurements

(in mm). D = 13.1–13.4, H = 5.8–6 (n=2, Vn11-171).

Differential diagnosis

Halongella fruhstorferi and H. schlumbergeri are congeneric based on similarity of genital morphology. Halongella fruhstorferi is smaller than H. schlumbergeri, having a more fragile, lighter shell and weaker apertural lip and apertural fold. In shape, H. fruhstorferi resembles Gudeodiscus fischeri. However, H. fruhstorferi has a relatively smaller aperture, weaker sculpture (rather irregular growth lines instead of regular ribs) and an anterior lamella is absent. Gudeodiscus phlyarius and the similar species (G. anceyi, G. hemmeni sp. n., G. messageri) have a well-developed anterior lamella or denticles at the position of the anterior lamella.

Intraspecific diversity

The species is known from a very small area, and only few specimens are known. The intraspecific diversity is low.

Description of the genitalia

One specimen was examined anatomically. Locality: Quảng Ninh Province, Vân Đồn Island (NE Cẩm Phả), Cái Rồng village, 21°3.560'N, 107°25.551'E, leg. Hemmen, Ch. & J., 14.08.2011. (Figures 25, 29C, 29I, 32A–B).

Penis relatively long, spindle-shaped, inner wall with several (at least 20) parallel running folds (Figure 29C); between the folds flat and very fine calcareous granules were found; epiphallus shorter than the penis, its inner wall with six parallel folds; on the distal portion of the epiphallus the longitudinal folds have several perpendicular projections which overlap with those of the neighbouring fold (Figure 29I); penial caecum absent, the retractor muscle inserts on the penis-epiphallus transition. Vagina long, with a relatively well-developed vaginal bulb; it is attached to the body wall by connective tissue; inner wall of the vagina with at least 16, more or less parallel folds; a few irregularly shaped calcareous granules have been found between the folds (Figure 32A–B); stalk of gametolytic sac longer with thickened gametolytic sac, diverticulum slimmer without conspicuous distal thickening. There were two developing embryos in the uterus. The embryos were surrounded with egg capsules which had several calcareous granules.

Radula

See Table 6 and Figures 36A–C.

Distribution

(see Figure 40): The species is known only from Kebao Island (Hạ Long Bay area).

Halongella schlumbergeri (Morlet, 1886a)

Figures 6A–D, 9M–N, 14H–N, 26, 29A–B, 29H, 30G–I, 33A–G, 36D–F, 45B

1886a Helix (Plectopylis) Schlumbergeri Morlet, Journal de Conchyliologie, 34: 259, 272–274., Plate 12., Figs 2a–c. [“Baie d’Along et montagne de l’Éléphant”].

1886b Helix (Plectopylis) Schlumbergeri Morlet, Diagnoses de mollusques terrestres et fluviatiles du Tonkin. 1–2.

1887b Plectopylis Schlumbergeri, — Mabille, Bulletin de le Société Malacologique de France, 4: 101–102.

1887b Plectopylis jovia Mabille, syn. n., Bulletin de le Société Malacologique de France, 4: 99–100. [“Circa locum dictum Halong”].

1887 Helix schlumbergeri, — Tryon, Manual of Conchology. 2 (3): 166, Plate 36., Figs 25–28.

1888 Plectopylis Schlumbergeri, — Ancey, Le Naturaliste, 2(10): 72.

1893 Plectopylis jovia, — Pilsbry, Manual of Conchology..., 2 (8): 156–157.

1893 Plectopylis villedaryi, — Pilsbry, Manual of Conchology..., 2 (8): 158., Plate 43., Figs 36–39.

1894 Plectopylis jovia, — Pilsbry, Manual of Conchology...: 146., Plate 40., Figs 1–4.

1897b Plectopylis schlumbergeri, — Gude, Science Gossip, 4: 138., Figs 58a–b. [“Halong Bay and Elephant Mountain, Tonkin”].

1897b Plectopylis jovia, — Gude, Science Gossip, 4: 138–139., Figs 59a–b. [“Halong”].

1899a Plectopylis schlumbergeri, — Gude, Science Gossip, 5: 332.

1899a Plectopylis jovia, — Gude, Science Gossip, 5: 332.

1899c Plectopylis (Endoplon) schlumbergeri, — Gude, Science Gossip, 4: 148.

1899c Plectopylis (Endoplon) jovia, — Gude, Science Gossip, 4: 148.

1899d Plectopylis (Endoplon) schlumbergeri, — Gude, Science Gossip, 6: 175.

1899d Plectopylis (Endoplon) jovia, — Gude, Science Gossip, 6: 175.

1901 Plectopylis (Endoplon) hirsuta Möllendorff, syn. n., Nachrichtsblatt der Deutschen Malakozoologischen Gesellschaft, 33 (5/6): 114–115. [“in insula Bah-mun”].

1901a Plectopylis Schlumbergeri, — Gude, Journal de Conchyliologie, 49: 199.

1901a Plectopylis Villedaryi, — Gude, Journal de Conchyliologie, 49: 212. [“Llots de la baie d’Along”].

1901b Plectopylis jovia, — Gude, Journal of Malacology, 8: 47–48., Figs 1a–b.

1901b Plectopylis schlumbergeri, — Gude, Journal of Malacology, 8: 47–48., Figs 2a–b.

1901b Plectopylis villedaryi, — Gude, Journal of Malacology, 8: 47–48., Figs 3a–b.

1901c Plectopylis pilsbryana Gude, syn. n., Journal of Malacology, 8: 110., [“Lang-Son, Bac-Ninh (Vathelet). Isles in Along Bay (Messager). Tonkin (Fruhstorfer)”].

1901c Plectopylis (Endoplon) hirsuta, — Gude, Journal of Malacology, 8: 111–112., Figs 1a–f. [“Island Bah-Mung”].

1901c Plectopylis (Endoplon) jovia, — Gude, Journal of Malacology, 8: 111–112., Figs 1a–f.

1905a Plectopylis Schlumbergeri, — Dautzenberg & Fischer, Journal de Conchyliologie, 53: 93.

1905a Plectopylis jovia, — Dautzenberg & Fischer, Journal de Conchyliologie, 53: 93.

1905a Plectopylis Villedaryi, — Dautzenberg & Fischer, Journal de Conchyliologie, 53: 93.

2013 Gudeodiscus schlumbergeri, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde 142 (1): 8.

2013 Gudeodiscus pilsbryana, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus jovius, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

2013 Gudeodiscus hirsutus, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 8.

Types examined

Llots de la Baie d’Along, leg. Messager (n. 23.), MNHN IM-2010-12119. (cited in Journal de Conchyliologie, 49: 212. as villedaryi); Tonkin, Halong, leg. l’Abbé Vathelet, MNHN 24580 (one adult and one juvenile syntypes of jovia, Figure 6B); Tonkin, NHMUK 1922.8.29.52 (holotype of pilsbryana, Figure 6C); Tonkin, MNHN 24582 (2 syntypes of schlumbergeri, Figure 6A); Tonkin, Bah-Mun, coll. Möllendorff ex Fruhstorfer, SMF 9277 (lectotype of hirsuta, Figure 6D); same data, SMF 9278 (2 paralectotypes of hirsuta).

Museum material examined

Tonkin, That-Khé, coll. Dosch ex Rolle ex Messager, SMF 341737/2; Tonkin, ex Fruhstorfer, SMF 150132/2; Tonkin, Tafel Insel, ex Fruhstorfer, H. 126, SMF 150131/2; Tonkin, Isle de la Table, coll. Ehrmann ex Webb, W. F., SMF 150130/3; Tonkin, Isle de la Table, coll. Ehrmann ex Webb, W. F., SMF 150124/1; Tonkin, coll. Ehrmann ex Fruhstorfer, H., SMF 150123/1; Tonkin, rochers de Kuy-Dong-Kay, coll. Jaeckel, S. H., SMF 207677/2; Tonkin, Isle de la Table, SMF 207678/1; Tonkin, rochers de Nuy-Dong-Nay, coll. Schlickum 3969 ex Staid (?), SMF 277560/2; Tonkin, Than-Moi, coll. Jaeckel, S. H., SMF 207670/4; Tonkin, rochers de Nuy-Dong-Nuy, coll. Pfeiffer, K. L. ex Sundler, October 1940, SMF 102825/2; Tonkin, Ile de la Table, Baie d’Along, SMF 294868/2; Tonkin, coll. Dosch ex Rolle, SMF 172096/2; Tonkin, Ile de la Table, coll. Dosch ex Rolle ex Webb, SMF 172094/2; Tonkin, Ile des Merveilles, coll. Möllendorff ex Fruhstorfer 130, SMF 150129/2; Tonkin, Hai-fong, coll. Möllendorff ex Fruhstrofer, SMF 150128/1; Hongay, leg. Drimmer, 09.11.1986. ex Kovács, Gy., HNHM 67079/2; Hongay, leg. Drimmer, 09.11.1986., HNHM 78324/4; Nuy Dong Nay, leg. Drimmer, HNHM 67068/1; Tonkin: Roches de Nuy-Dong-Nay HNHM 37877/2; Tonkin, coll. Mansuy, MNHN-IM-2012-2260/4; Tonkin, coll. Sayer 1969, MNHN-IM-2012-2261/1; Tonkin, leg. abbe Wathelet, MNHN-IM-2012-2262/3; Baie d’Along, Ile de le Table, coll. Lavezzari ex Bernays, MNHN-IM-2012-2264/3; Tonkin, coll. Balansa 1887, MNHN-IM-2012-2269/4; Baie d’Halong, excoll. labo. de Géologie de la Sorbonne (entrée 1952), MNHN-IM-2012-2271/2; Baie d’Halong, coll. Staadt, 1969, MNHN-IM-2012-2280/1 juvenile shell; Baie d’Along, Ile de la Table, MNHN-IM-2012-2289/3; Tonkin, coll. Staadt 1969, MNHN-IM-2012-2291/24; Tonkin, coll. Balansa 1887, MNHN-IM-2012-2294/4; Halong, MNHN-IM-2012-2295/2; Grotte des Merveilles, coll. Saurin, MNHN-IM-2012-2299/7; Tonkin, coll. Letellier, 1949, MNHN-IM-2012-2304/1; Halong Bay, leg. Messager, MNHN-IM-2012-2316/1; Halong Bay, leg. Messager, MNHN-IM-2012-2317/4; Halong Bay, leg. Messager, MNHN-IM-2012-2322/4; No locality, leg. V. Demange, 29.01.1931, coll. Staadt, 1969, MNHN-IM-2012-2329/298; Tonkin, coll. Denis, MNHN-IM-2012-2332/6; Rochers de Nuy-Dong-Nay, MNHN-IM-2012-2481/529; Tonkin, coll. Staadt. 1969, MNHN-IM-2012-2444/366; Dong-Trien, coll. Blaise, 1902, MNHN-IM-2012-2347/1; Dong-Trien, coll. Blaise, 1903, MNHN-IM-2012-2348/1; Ile de la Table, coll. Staadt, 1969, MNHN-IM-2012-2350/4; Ile Krieu, coll. Blaise, MNHN-IM-2012-2362/2 juvenile shells; Lang-Son, coll. Letellier, 1949, MNHN-IM-2012-2366/1; Ile de la Table, coll. Demange, MNHN-IM-2012-2367/5; Dong-Trieu, coll. Blaise, MNHN-IM-2012-2368/2; Halong Bay, leg. Messager, MNHN-IM-2012-2369/3; Halong Bay, leg. Messager, MNHN-IM-2012-2370/3; Halong Bay, leg. Messager, MNHN-IM-2012-2375/6; Tonkin, coll. Fischer, ex Crosse, MNHN-IM-2012-2380/2; Ilots de la Baie d’Along, leg. Messager, MNHN-IM-2012-2381/2; Tonkin, leg. Messager, MNHN-IM-2012-2388/1; Tonkin, coll. Lucas, Acc. no. 2351, NHMUK 20130622/2; Hanoi, Ile de la Table, coll. Biggs, H.E.J. ex Tomlin, 1931, Acc. no. 2258, NHMUK 20130623/8; Tonkin, coll. Salisbury ex Beddome, NHMUK 20130624/1; Tonkin, Ile de la Table, NHMUK 20130625/4; Tonkin, Ile de la Table, NHMUK 1901.12.12.211–212/2; Tonkin, Ile des Merveilles, NHMUK 1901.12.12.232–233/2; Tonquin, NHMUK 1889.9.23.1. (2 shells); Tonkin, Bah-Mun, coll. Dosch ex Rolle, SMF 172085/2 (“hirsuta”); Tonkin, Bah-Mun, coll. Ehrmann ex Fruhstorfer, SMF 150137/2 (“hirsuta”); Bah-Mun, leg. Fruhstorfer, 29.10.1900, RBINS/2 (“hirsuta”); Golfe de Tonkin, coll. Achat Boubée, MNHN-IM-2012-2307/1 (“hirsuta”); Tonkin, coll. Salisbury ex Beddome, NHMUK 20110254/1 (“hirsuta”); Tonkin, coll. Rolle, 4/11/01-25, NHMUK 20110264/3 (“hirsuta”); Tonkin, NHMUK 1916.3.16.10/1 (“hirsuta”); Tonkin, Bah-Mun, NHMUK 1901.12.23.32–34/3 (“hirsuta”); Tonkin, That-Khé, coll. Werner ex Rolle, NHMW 75000/E/7814/2; Tonkin, That-Khé, coll. Klemm, NHMW 79000/K/17484/3; Golf de Tonking, Ile de la Table, coll. Edlauer, NHMW 75000/E/14744/2; Tonkin, Ile Table, coll. Rušnov, NHMW 92583/2; Ile de la Table, Ban Valong (?), coll. Oberwimmer ex Caziot, NHMW 71640/O/9650/2; Tonkin, Ile de la Table, NHMW 92582/2; Tonkin, coll. Fruhstorfer, NHMW 40849/1; Tonkin, That-Ke, coll. Wagner ex Messager, NHMW 103351/2 (mixed sample with dautzenbergi); Tonkin, NHMW 46025/1 (“hirsutus”); Cha-Ban, Baie d’Along, Tonkin, coll.Steenberg, ZMUC-GAS-1814/2.

New material examined

20081119A Hải Phòng Province, Hải Phòng City, Cát Bà Isl., Cát Bà Nat. Park, beyond Mây Bầu, ca 160 m, 20°47.763'N, 107°00.758'E, leg. Ohara, K. 19.11.2008., PGB/2, OK/13; 20071122B same data, leg. Okubo, K., 22.11.2007., PGB/2; 20071122A Hải Phòng Province, Hải Phòng city, Cát Bà Island, Cát Bà Nat. Park, near pass in front of Mây Bầu, ca 100 m, 20°47.81769'N, 107°00.42256'E, leg. Ohara, K., 22.11.2007., OK/4, PGB/1; 20081118A Quảng Ninh Province, Hạ Long Bay, Đầu Gỗ Isl., near Đầu Gỗ Cave, ca 15 m, 20°54.696'N, 107°01.069'E, leg. Ohara, K., 18.11.2008., OK/14, PGB/2; GS25 Quảng Ninh Province, Hạ Long Bay, Đầu Gỗ Cave, N. Đầu Gỗ Island, in leaf litter in limestone crackings, leg. Grego, J., 08.04.2012., PGB/1 broken specimen; 20071122C Hải Phòng City, Cát Bà Island, Cát Bà N.P., beyond Mây Bầu peak, 165 m, 20°47.70504'N, 107°00.85709'E, leg. Ohara, K., 22.11.2007., PGB/1; MAA7 Quảng Ninh Province, Hạ Long Bay Area, Áng Dù Island, 20°47.61'N, 107°08.05'E, coll. Maassen, W.J.M., 15.09.2003., PGB/2, WM/8; MAA8 Hải Phòng Province, Cát Bà Island, half way path lake Ao Ek and Park HQ, 20°47.45'N, 107°00.00'E, leg. Vermeulen, J., coll. Maassen, W.J.M., 27.09.2003. (2 shells); MAA11 Quảng Ninh Province, Hạ Long Bay Area, Tiên Ông Cave on Hang Trai? Island, collected near the entrance of the cave, 20°48.96'N, 107°07.33'E, coll. Maassen, W.J.M. 06.09.2003., (1 shell).; no code Quảng Ninh Province, Hạ Long Bay area, Cây Chanh Island, Cống Đỏ area, 20°52.56'N, 107°11.14'E, leg. Hemmen, Ch. & J., 2003, PGB/2 shells+1jb; MAA5 same data, coll. Maassen, W.J.M., 13.09.2003., PGB/2, WM/14; MAA2 Quảng Ninh Province, Hạ Long Bay Area, Cống Đỏ Isl., NE coast, 20°52.44'N, 107°12.10'E, leg. Vermeulen, J., 03.10.2003., coll. Maassen, W.J.M., WM/2; MAA3 Quảng Ninh Province, Hạ Long Bay Area, unnamed island in Cống Đỏ area, 20°52.47'N, 107°11.72'E, coll. Maassen, W.J.M., 03.10.2003., PGB/1, WM/3); MAA4 Quảng Ninh Province, unnamed island in Đảo Mới Temper area, 20°55.69'N, 107°09.40'E, coll. Maassen, W.J.M., 13.09.2003., PGB/2, WM/18; MAA6 Quảng Ninh Province, Hạ Long Bay Area, Phao Trong Island, 20°49.80'N, 107°08.32'E, coll. Maassen, W.J.M., 11.09.2003., PGB/1, WM/5; 2012/26 Hải Phòng Province, Ðảo Cát Bà (island), Cát Bà Nat. Park, 500 m from the entrance towards Ao Ếch, 60 m, 20°47.945'N, 106°59.653'E, leg. Hunyadi, A., 22.05.2012., HA/1+2jb; 2012/28 Hải Phòng Province, Ðảo Cát Bà, Cát Bà Nat. Park, Ao Ếch 500 m towards Mây Bầu, 60 m, leg. Hunyadi, A., 22.05.2012., HA/25+1jb; 2012/32 Quảng Ninh Province, Đèo Bụt (pass) 1 km towards Cẩm Phả, right side of the road, 10 m, 20°58.680'N, 107°11.089'E, leg. Hunyadi, A., 23.05.2012., HA/11+1jb; 2012/34 Quảng Ninh Province, ÐảoTrà Bản (island), Cảng Bản Sen (harbour) 1.5 km towards Cảng Tân Lập (harbour), right side of the road, 30 m, 20°56.943'N, 107°29.772'E, leg. Hunyadi, A., 24.05.2012., HA/84+3jb; 2012/35 Quảng Ninh Province, ÐảoTrà Bản (island), Cảng Bản Sen (harbour) towards the Cảng Tân Lập (harbour) cross, 200 m, right side of the road, 35 m, 20°56.456'N, 107°29.870'E, leg. Hunyadi, A., 24.05.2012., HA/12; Vn11-172 Hải Phòng Province, Cát Bà Island, behind cemetery of Gia Luận village, 20°50.092'N, 106°58.560'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/6 (anatomically examined); Vn11-173 Hải Phòng Province, Cát Bà Island, at km 4 road Gia Luận village to Cát Bà village, 20°49.991'N, 106°58.382'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/11, PGB/1 (in ethanol); Vn11-174 Hải Phòng Province, Cát Bà Island, between Hiền Hào and Cát Bà village near Xuân Đán, 20°45.479'N, 106°58.556'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/8; Vn11-175 Hải Phòng Province, Cát Bà Island, between Hiền Hào and entrance of Cát Bà N.P. (road over Hiền Hào), 20°47.681'N, 106°59.068'E, leg. Hemmen, Ch. & J., 11.04.2011., HE/4; Vn11-38A Hải Phòng Province, Cát Bà Island, Hoa Cương Cave (=Dong Da Hoang?), near Gia Luận, ca. 30 m, 20°50.268'N, 106°59.019'E, leg. Hemmen, Ch. & J., 10.04.2011., HE/5; Vn11-165 Quảng Ninh Province, ca. 8.3 km west of Cẩm Phả ca 200 m right of road 18 (no GPS-data), leg. Hemmen, Ch. & J., 03.04.2011., HE/1; VERM1 Cát Bà, Hải Phòng Province, Cát Bà Island, path from Nat. Park HQ to lake Ao Ek, 20°47.45'N, 107°00.45'E, Primary forest on limestone. Mainly handpicked. leg. Vermeulen, J.J. & Whitten, A.J., 25.09.1998, NHMUK 19991447/4; VERM3 Hạ Long Quảng Ninh Province, Hạ Long-Cẩm Phả area. Limestone hill S of Hạ Long, with marked regrowth and bamboo thickets, 20°57.00'N, 107°04.43'E, handpicked + soil sample, leg. Vermeulen, J.J. & Whitten, A.J., 28.09.1998 ex Vermeulen, nr. 6527, NHMUK 19991445/3; 20071122D Hải Phòng Province, Hải Phòng City, Cát Bà Island, Cát Bà Nat. Park, between Cát Bà N.P., ranger st. and Quan Y, GPS not recorded, leg. Ohara, K, Okubo, K. & Otani, J. U., 22.11.2007., coll PGB (in ethanol, anatomically examined).

Diagnosis

Shell medium-sized to very large, thick shelled, almost smooth or with very fine periostracal ribs; apertural lip well-developed; apertural fold long, more or less equally long in its total length, connected to the callus. Parietal wall with missing or short anterior lamella (always distant from the upper plica) and well-developed posterior lamella; palatal plicae depressed Z-shaped.

Measurements

(in mm). D = 16.6–17.1, H = 8.3–8.5 (n=2, MAA5); D = 17.4–19.9, H = 7.9–9.2 (n=2, MAA4); D = 16.1–19.8, H = 7–9.4 (n=2, MAA6); D = 23.1–23.4, H = 10.8–11 (n=2, 20081119A); D = 24.8–25.6, H = 11.7–13 (n=4, Vn11-174); D = 26–28.1, H = 12.8–13.1 (n=3, Vn11-175); D = 16.9–17.4, H = 8.2–8.4 (n=3, NHMUK 20110264, “hirsuta”); D = 16.5–17.3, H = 8.1–8.5 (n=3, NHMUK 1901.12.23.32–34, “hirsuta”) (see also Figure 44).

Differential diagnosis

Gudeodiscus dautzenbergi and some populations of G. villedaryi resemble Halongella schlumbergeri in terms of general, but the inner lamellae are entirely different, namely, G. dautzenbergi and G. villedaryi have strong, well-developed anterior lamella with an anteriorly elongated lower “leg”, whereas most H. schlumbergeri shells lack the anterior lamella. It is possible to distinguish H. schlumbergeri from the other two species without breaking the shell, on the basis of the long apertural fold reaching the callus, which is short in G. dautzenbergi and G. villedaryi, and has an elevated “knob” part in some distance from the callus. See also under H. fruhstorferi.

Intraspecific diversity

The species is very variable in terms of shell size and the formation of plicae and lamellae on the parietal wall.

Description of the genitalia

Two specimens were examined anatomically each from one of two different samples. “Specimen1”: Hải Phòng Province, Cát Bà Island, behind cemetery of Gia Luận village, 20°50.092'N, 106°58.560'E, leg. Hemmen, Ch. & J., 10.04.2011. (with embryo in its uterus, Figures 26, 29H, 33B, F); “Specimen2”: Hải Phòng Province, Hải Phòng City, Cát Bà Island, Cát Bà Nat. Park, between Cát Bà N.P., ranger st. and Quan Y, GPS not recorded, leg. Ohara, K, Okubo, K. & Otani, J. U., 22.11.2007. (without embryo in its uterus, Figures 29A–B, 30G–I, 33A, C–E, G).

Penis relatively long, slimmer proximally and slightly thicker distally; inner wall with several (16–18) parallel running folds (Figures 29A–B); between the folds flat, T-shaped calcareous granules were found (both specimens had granules between the folds, see Figures 30G–I); epiphallus of similar length to the penis, proximally thicker than distally; its inner wall with six parallel folds; on the distal portion of the epiphallus the longitudinal folds have several perpendicular projections which overlap with those of the neighbouring fold (Figures 29H); penial caecum absent, the retractor muscle inserts on the penis-epiphallus transition. Vagina long, with a weak vaginal bulb; it is attached to the body wall with several filaments of connective tissue; inner wall of the vagina with 6–11 parallel, rather regular longitudinal folds; in “Specimen2” there are several, translucent calcareous granules on the folds; the granules have a widened base portion which attaches to the folds, and an apical part with some (1–10) pointed needles (Figure 33A, C–E, G); “Specimen1” had tiny rounded granules (“sand”) in the vagina lumen, not attached to the vagina wall (Figure 33F); stalk of the gametolytic sac with conspicuously thickened gametolytic sac is longer than the much slimmer diverticulum.

Radula

See Table 6 and Figures 36D–F.

Distribution

(see Figures 40 and 44). The species has only been recorded in the Hạ Long Bay area (Hải Phòng and Quảng Ninh provinces).

Remarks

Gude (1901b) figured specimens of all three “species”: schlumbergeri, jovia and villedaryi (later re-named pilsbryana). His observations were based on one specimen from each “species”. He wrote the following: “A comparison of these three species has shown that that they are very closely allied, and that there is no difference of diagnostic value between the armature. They differ, however, in external aspect sufficiently to rank as separate forms. P. jovia is the largest of the three, while P. villedaryi is the smallest, P. schlumbergeri being intermediate in size.” The additional differences mentioned by Gude, namely the strength of the callus, direction and small differences in the shape of the palatal and parietal lamellae and plicae are not sufficient to separate species. We had the possibility to observe and measure a number of shells collected in the Hạ Long Bay Area and provided with exact GPS data. The outer shell characters exhibit little variation other than in size. Therefore, we suggest synonymising the three species under one name.

The shell differences between Plectopylis schlumbergeri (and its synonyms) and Plectopylis hirsuta, namely the short or missing anterior lamella in schlumbergeri and the relatively “normal” anterior lamella of hirsuta are considered to be very minor. This trait shows clinal variation across shells assigned to hirsuta and schlumbergeri (and its synonyms). We therefore synonymize Plectopylis hirsuta with Halongella schlumbergeri.

Sicradiscus Páll-Gergely, 2013

Type species

Plectopylis schistoptychia Möllendorff, 1886, by original designation.

Diagnosis

See introduction.

Differential diagnosis

Gudeodiscus differs from the keeled shell of Sicradiscus by the rounded body whorl. Sicradiscus species having rounded body whorl differ from Gudeodiscus by the combination of small shells with glossy base, a strong apertural fold connected to the callus, and short or divided palatal plicae. In contrast, Gudeodiscus species have usually large, mainly finely ribbed shells with weak apertural folds free from the callus (often absent) and long, depressed Z-shaped palatal plicae. See also under Halongella gen. n. and under the Discussion.

Sicradiscus mansuyi (Gude, 1908)

Figures 2A, 9H, 11A–B, 27, 31A, 36J–L

1908 Plectopylis Mansuyi Gude, Journal de Conchyliologie, 55: 347, 348–351., Figs 2a–e, Plate 7., Figs 1–3. [“Ha-Lang, Tonkin”]

2013 Sicradiscus mansuyi, — Páll-Gergely & Hunyadi, Archiv für Molluskenkunde, 142 (1): 50.

Types examined

Tonkin, Ha-Lang, leg. Mansuy, NHMUK 1907.2.20.19 (syntype, Figure 2A).

Museum material examined

Ha-Lang, coll. Mansuy, MNHN-IM-2012-2365/6; Ha-Lang, leg. Mansuy, MNHN-IM-2012-2384/7; HaLang, Tonkin, coll. Steenberg, ZMUC-GAS-1808/2.

New material examined

20081116C Cao Bằng Province, Trùng Khánh District, Cảnh Tiên Commune, Pắc Rảo Village, ca 545 m, 22°48.941'N, 106°30.549'E, leg. Ohara, K., 16.11.2008., OK/66, PGB/5; 2011/81 Cao Bằng Province, Đèo Mã Phục (pass) 500 m towards Quảng Uyên, left side of the road, rock cavern, 610 m, 22°43.981'N, 106°20.333'E, leg. Hunyadi, A., 14.11.2011., HA/10; 2012/43 Cao Bằng Province, Pắc Rảo, Cảnh Tiên Commune cross, 300 m towards Trùng Khánh, right side of the road, 530 m, 22°49.385'N, 106°30.742'E, leg. Hunyadi, A., 28.05.2012., HA/9+5 jb; 2012/44 Cao Bằng Province, southern edge of Pắc Rảo, Trùng Khánh 3 km towards Quảng Uyên, left side of the road, 570 m, 22°48.961'N, 106°30.533'E, leg. Hunyadi, A., 28.05.2012., HA/226; 2012/47 Hà Giang Province, Hà Giang 105.5 km towards Ðồng Văn, Vân Chải Commune, left side of the road 4C, 23°09.084'N, 105°10.774'E, leg. Hunyadi, A., 31.05.2012., HA/4; Vn11-141 Hà Giang Province, km 105.5 on road 4c, between Yên Minh and Đồng Văn (NE of Hà Giang town), 23°08.996'N, 105°10.332'E, leg. Hemmen, Ch., 21.03.2011., HE/6; Vn11-143 Hà Giang Province, km 120 on road 4c, between Yên Minh and Đồng Văn (NE of Hà Giang town), no GPS-data, leg. Hemmen, Ch. & J., 22.03.2011., HE/3; Vn10-60 Cao Bằng Province, ca. 6.5 km from Quảng Uyênto Mã Phục (left off road), 22°41.293'N, 106°23.422'E, leg. Hemmen, Ch. & J., 24.03.2010., HE/2; 20050327A China, Guangxi (广西), Daxin Xian (大新), Xialei Zhen (下雷鎮), Detianpubu (德天瀑布) (Detian waterfalls), leg. Ohara, K. & Moriya Shigeki, 27.03.2005., PGB/1 (with glossy dorsal surface and without denticles posterior to the palatal plicae).

Diagnosis

A very small species with reticulated dorsal and glossy ventral surface, elevated spire, elevated, sharp callus and well-developed apertural fold connected to the callus (Figure 9H). Parietal wall with two lamellae, the anterior one separated from both the lower and upper plicae; middle palatal plicae short, connected with a ridge and sometimes ornamented with small denticles posteriorly (Figures 11A–B).

Measurements

(in mm). D = 6.7–7, H = 3.4–3.9 (n=4, 20081116C).

Differential diagnosis

All other similar congeners inhabit China. Sicradiscus feheri Páll-Gergely & Hunyadi, 2013 is larger, flatter with a wider umbilicus and a shinier dorsal surface, has a longer, horizontal palatal plicae without additional posterior denticles, and has a more elevated and longer apertural fold. Sicradiscus transitus Páll-Gergely & Hunyadi, 2013 has a lower spire and a wider umbilicus with slightly shouldered whorls, sometimes strong radial lines on the ventral surface, and a more elevated callus. Moreover, the anterior lamella of S. transitus is in contact with both the upper and the lower plicae, which are free from the lamella in S. mansuyi. Sicradiscus invius is flatter (has shallower umbilicus) with only the protoconch elevated from the dorsal surface; it has weaker dorsal sculpture resulting in a glossy surface (mansuyi is densely reticulated), and lacks the additional small denticles posterior to the palatal plicae, which are usually present in S. mansuyi. Gudeodiscus anceyi is larger and has a ribbed shell with spiral lines on the whole shell. Species possessing a glossy ventral surface (G. cyrtochilus, G. fischeri) are also larger and have weaker or no apertural fold.

Intraspecific diversity

Low; shell characters stable. The species is easily recognisable and can be separated from other plectopylid species without difficulty.

Description of the genitalia

Two specimens were anatomically examined (Cao Bằng Province, southern edge of Pắc Rảo, Trùng Khánh 3 km towards Quảng Uyên, left side of the road, 570 m, 22°48.961'N, 106°30.533'E, leg. Hunyadi, A., 28.05.2012. (Figures 27, 31A).

Penis with a shorter, slimmer proximal section and a thinner, somewhat longer distal portion; internally with parallel folds which are more elevated in the thinner distal portion, forming pocket-like structures (similar to that of S. transitus, see Páll-Gergely and Asami 2014); these “pockets” did not contain granules; epiphallus approximately as long as the penis but much slimmer; internally penis and epiphallus wall with longitudinal, parallel folds; retractor muscle short, inserts on the penis-epiphallus transition; penial caecum absent. Vagina long, with distal vaginal bulb; vaginal bulb and other parts of the vagina with approximately 8, more or less parallel, serrulate folds (Figure 31A); vas deferens long, thicker distally and more slender proximally; gametolytic sac and diverticulum are of equal length, in parallel.

Radula

See Table 6 and Figures 36J–L.

Distribution

This species was described from Hạ Lang (eastern part of Cao Bằng Province, see Figure 39). We have seen newly collected material from northern Hà Giang and Cao Bằng provinces. The first occurrence of the species from China is reported. This locality is situated very close to the Vietnamese border.

Concluding remarks

Identification and species recognition

For this revision of the Vietnamese Plectopylidae, we examined the type specimens of all known taxa, 197 newly collected specimens with detailed locality data and 631 historical lots deposited in a variety of public collections. Altogether we examined more than 7000 shells (see Table 12). We found specimens of most species in European museum collections, probably because of intensive shell exchanges at the beginning of the 20th Century. The present scale of specimen examination allowed us to understand species boundaries in the Vietnamese Plectopylidae better than the preceding studies.

Numbers of specimens examined in each taxon.

taxon new samples museum samples all individuals
anceyi 16 49 1079
cyrtochilus 8 2 71
dautzenbergi 4 38 151
emigrans emigrans 0 2 3
emigrans quadrilamellatus 4 23 68
fischeri 15 14 169
francoisi 6 31 142
fruhstorferi 1 5 37
giardi giardi 21 74 557
hemmeni sp. n. 5 0 38
mansuyi 8 3 351
messageri 0 102 551
messageri raheemi 23 0 152
typical phlyarius 34 44 555
phlyarius gouldingi/fallax 2 139 1138
schlumbergeri 28 78 1682
suprafilaris 7 2 102
verecundus 0 6 25
villedaryi 15 19 171
SUM 197 631 7042

Although the plicae and lamellae (especially on the parietal wall) are common characteristics of the family and useful for identification of some species, their value in species recognition has been somewhat overestimated. This appears to have led to descriptions of several species that differ only slightly in palatal and parietal plication. Our recognition of distinct species is primarily based on general shell and aperture shape, and secondarily on the morphology of plicae and lamellae.

Key characters for identification (see also identification key)

As a summary, below we present the most important shell characters for identification of each species from others within the Vietnamese Plectopylidae. In the case of Gudeodiscus emigrans emigrans and G. infralevis, however, available shell specimens were insufficient to provide help for “routine” identification.

anceyi (Figs 2B, 9G, 11C–F): small size, spiral lines on the ventral surface

cyrtochilus (Figs 2F, 15E–G): small size, thin peristome and callus, no apertural fold

dautzenbergi (Figs 8E–F, 9K–L, 14A–G): shell shape, characteristic aperture and apertural fold, free lower parietal plica absent

emigrans quadrilamellatus (Figs 6F, 13C–D): flat shell, spiral lines

fischeri (Figs 2E, 3A–C, 9P–Q, 15H–N): nautiliform shape (body whorl is conspicuously wider than the previous), blunt callus and apertural fold

francoisi (Figs 7A–C, 13E–K): slowly expanding whorls, characteristic aperture

fruhstorferi (Figs 7D, 9O, 14O–R): few whorls, aperture with thin rim and apertural fold

giardi (Figs 7E–F, 8A, 9I, 13L–U): shell shape, narrow umbilicus, thick peristome

hemmeni (Figs 2C–D, 9F, 11G–J): small size, minute apertural fold, characteristic aperture shape

mansuyi (Figs 2A, 9H, 11A–B): small size, glossy ventral surface

messageri messageri (Figs 5F–G, 9E, 12N–Q): slightly elevated spire, callus not angled in the middle, apertural fold always missing

messageri raheemi (Figs 5D, 5E, 10A, 12R–V): body whorl less shouldered than that of the nominotypical subspecies, but plicae have to be observed for correct identification

phlyarius (typical phlyarius; Figs 4A–B, 10C–D, 12A–M): characteristic rounded aperture, apertural fold always present

phlyarius (typical fallax; Figs 5A, 5C, 10E–F, 11Q–X): flat shell, callus angled in the middle, shell large, nautiliform (body whorl conspicuously wider than messageri raheemi)

phlyarius (typical “anterides” and “gouldingi”; Figs 4–F, 9D, 11K–P): small, flat shell, callus angled in the middle

phlyarius (typical “verecunda”; Figs 5B): elevated spire, strong apertural fold

schlumbergeri (Figs 6A–D, 9M–N, 14H–N): robust shell, callus and aperture shape (including the formation of the fold)

suprafilaris (Figs 9A–B, 9R, 14S–Y): narrow umbilicus, solid aperture, sculpture changing suddenly on the body whorl

villedaryi (Figs 8B–D, 9J, 10B, 13V–Y): aperture shaped characteristically, unique keel around the umbilicus in some populations, free lower parietal plica present

Figure 2.

Shells of Vietnamese Sicradiscus and Gudeodiscus species. A Sicradiscus mansuyi (Gude, 1908), NHMUK 1907.2.20.19 (syntype) B Gudeodiscus (Gudeodiscus?) anceyi (Gude, 1901), Tonkin, Bac-Kan, leg. Messager, MNHN 24600 (syntype) C G. (G.?) hemmeni Páll-Gergely & Hunyadi, sp. n., 2012/61, HNHM 97458 (holotype) D G. (G.?) hemmeni, Vn10-103 E G. (G.) fischeri (Gude, 1901), 20090519B, coll. PGB F G. (G.?) cyrtochilus (Gude, 1909), NHMUK 1922.8.29.59. (syntype). Photos: H. Taylor (A, F), T. Deli (B) and B. Páll-Gergely (C, D, E). Scale represents 10 mm.

Figure 3.

Shells of Vietnamese Gudeodiscus species. A Gudeodiscus (Gudeodiscus) fischeri (Gude, 1901), Vn10-120, coll. PGB B G. (G.) fischeri, MNHN 24579 (holotype of Plectopylis fischeri) C G. (G.) fischeri, MNHN 24587 (holotype of Plectopylis tenuis) D G. (G.?) infralevis (Gude, 1908), MNHN 24604 (holotype of Plectopylis infralevis) E G. (G.?) infralevis, MNHN 24585 (holotype of Plectopylis soror). Photos: B. Páll-Gergely (A) and T. Deli (B–E). Scale represents 10 mm.

Figure 4.

Shells of Vietnamese Gudeodiscus species. A Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887), MNHN 24581 (syntype of Plectopylis phlyaria) B G. (G.) phlyarius, SMF 150125a (lectotype of Plectopylis moellendorffi) C G. (G.) cf. phlyarius, Vn10-41, coll. PGB D G. (G.) phlyarius, Vn09-06, coll. HE E G. (G.) phlyarius, NHMUK 1922.8.29.56 (holotype of Plectopylis gouldingi) F G. (G.) phlyarius, NHMUK 1922.8.29.57 (holotype of Plectopylis anterides). Photos: T. Deli (A), E. Neubert (B), B. Páll-Gergely (C, D) and H. Taylor (F). Scale represents 10 mm.

Figure 5.

Shells of Vietnamese Gudeodiscus species. A Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887) (typical “fallax var. major”), MNHN-IM-2012-2155 B G. (G.) phlyarius, NHMUK 1922.8.29.55 (holotype of Plectopylis verecunda) C G. (G.) phlyarius, NHMUK 1922.8.29.58 (holotype of Plectopylis fallax) D G. (G.) messageri raheemi Páll-Gergely & Hunyadi, ssp. n., Vn10-76, coll. PGB E G. (G.) messageri raheemi ssp. n., NHMUK 20110370.1 (holotype) F G. (G.) messageri messageri (Gude, 1909), NHMUK 1922.8.29.53 (holotype) G G. (G.) messageri messageri NHMUK 1922.8.29.54 (syntype of P. messageri var. minor). Photos: B. Páll-Gergely (A, D), H. Taylor (B–C, E–G). Scale represents 10 mm.

Figure 6.

Shells of Vietnamese Halongella gen. n. and Gudeodiscus species. A Halongella schlumbergeri (Morlet, 1886), MNHN 24582 (syntype of Helix (Plectopylis) schlumbergeri) B H. schlumbergeri, MNHN 24580 (syntype of Plectopylis jovia) C H. schlumbergeri, NHMUK 1922.8.29.52 (holotype of Plectopylis pilsbryana) D H. schlumbergeri, SMF 9277 (lectotype of Plectopylis hirsuta) E Gudeodiscus (Veludiscus) emigrans emigrans (Möllendorff, 1901), SMF 9256 (lectotype) F G. (V.) emigrans quadrilamellatus Páll-Gergely, 2013, HNHM 97468 (holotype). Photos E and F were already published in Páll-Gergely and Hunyadi (2013). Photos: T. Deli (A, B), H. Taylor (C), S. Hof (D), E. Neubert (E) and B. Páll-Gergely (F). Scales represent 10 mm; upper scale belongs to A–B, lower scale belongs to C–F.

Figure 7.

Shells of Vietnamese Gudeodiscus and Halongella gen. n. species. A Gudeodiscus (Gudeodiscus?) francoisi (Fischer, 1898), MNHN 24601 (holotype of Plectopylis bavayi) B G. (G.?) francoisi, MNHN 9945 (holotype of Plectopylis francoisi) C G. (G.?) francoisi, NHMUK 1922.8.29.51 (holotype of Plectopylis lepida) D Halongella fruhstorferi (Möllendorff, 1901), SMF 9258 (lectotype) E G. (G.) giardi giardi (Fischer, 1898), MNHN IM-2010-12120 (syntype of Plectopylis congesta) F G. (G.) giardi giardi, NHMUK 1922.8.29.49 (syntype of Plectopylis congesta). Photos: T. Deli (A, B, E), H. Taylor (C, F) and E. Neubert (D). Scale represents 20 mm.

Figure 8.

Shells of Vietnamese Gudeodiscus and Halongella gen. n. species. A Gudeodiscus (Gudeodiscus) giardi giardi (Fischer, 1898), MNHN 9946 (syntype of Plectopylis giardi) B G. (G.) villedaryi (Ancey, 1888), SMF 9279 (lectotype of Plectopylis choanomphala) C G. (G.) villedaryi, NHMUK 1930.9.12.38 (holotype of Plectopylis villedaryi) D G. (G.) villedaryi, Vn11-152, coll PGB E G. (G.) dautzenbergi (Gude, 1901), MNHN 24603 (holotype) F G. (G.) dautzenbergi, MNHN 24602 (holotype of Plectopylis persimilis). Photos: T. Deli (A, E, F), S. Hof (B), H. Taylor (C) and B. Páll-Gergely (D). Scale represents 20 mm.

Figure 9.

Shells (A–B) and apertural views (C–R) of Vietnamese Gudeodiscus, Sicradiscus and Halongella gen. n. species. A Gudeodiscus (Gudeodiscus?) suprafilaris (Gude, 1908), MNHN 24586 (holotype?) B G. (G.?) suprafilaris, 2011/81 C G. (G.) phlyarius (Mabille, 1887), Vn11-156 D G. (G.) phlyarius (Mabille, 1887) (typical “anterides/gouldingi”), MNHN-IM-2012-2164 E G. (G.) messageri messageri (Gude, 1909), MNHN-IM-2012-2215 F G. (G.?) hemmeni Páll-Gergely & Hunyadi, sp. n., Vn10-103A G G. (G.?) anceyi (Gude, 1901), GS22 H Sicradiscus mansuyi (Gude, 1908), 20081116C I G. (G.) giardi giardi (Fischer, 1898), 2011/81 J G. (G.) villedaryi (Ancey, 1888), Vn11-151 K–L G. (G.) dautzenbergi (Gude, 1901), Vn10-44 M–N Halongella schlumbergeri (Morlet, 1886), MAA3 O H. fruhstorferi (Möllendorff, 1901), Vn11-171 P G. (G.) fischeri (Gude, 1901), Vn10-120 Q G. (G.) fischeri (Gude, 1901), 20090515C R G. (G.?) suprafilaris (Gude, 1908), 2011/81. All photos by B. Páll-Gergely except for Figure 9A (T. Deli). Scale represents 10 mm and refers to A and B.

Figure 10.

SEM images of Gudeodiscus shells. A protoconch of Gudeodiscus (Gudeodiscus) messageri raheemi Páll-Gergely & Hunyadi, ssp. n., Vn12-104, coll. HE B protoconch of G. (G.) villedaryi (Ancey, 1888), Vn11-163, coll. HE C–D sculpture of G. (G.) phlyarius (Mabille, 1887), Vn10-56, coll. HE E–F sculpture of G. (G.) phlyarius (Mabille, 1887) (typical fallax specimen), Vn11-187, coll HE. Images: B. Páll-Gergely.

Figure 11.

Parietal (A, C, E, G, I, K, M, O–Q, S, V) and palatal (B, D, F, H, J, L, N, R, T–U, W–X) plicae and lamellae of Sicradiscus and Gudeodiscus species. A–B Sicradiscus mansuyi (Gude, 1908), 20081116C (two different specimens) C–F Gudeodiscus (Gudeodiscus) anceyi (Gude, 1901) C–D figures in Gude (1901a) E MNHN-IM-2012-2263, F GS22 G–J G. (G.?) hemmeni Páll-Gergely & Hunyadi, sp. n. G–H 2012/62, spec.1 I–J 2012/62, spec.2 K–P G. (G.) phlyarius (Mabille, 1887) (typical gouldingi and anterides shells) K–L Plectopylis gouldingi (after Gude 1909) M–N Plectopylis anterides (after Gude 1909) O–P MNHN-IM-2012-2153 Q–X G. (G.) phlyarius (typical fallax and fallax var. major shells) Q–R Plectopylis fallax (after Gude 1909) S MNHN-IM-2012-2157 T–U MNHN-IM-2012-2132 (2 different specimens) V–W MNHN-IM-2012-2155/6 (“var. major”, two different specimens), X Vn11-187. Inner view: D, L, N, R; Outer view: B, F, H, J, T, U, W, X.

Figure 12.

Parietal (A, C, E, G–K, M, N, P–S, U, W) and palatal (B, D, F, L, P, T, V, X) plicae and lamellae of Gudeodiscus species. A–M Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887) A–B Plectopylis phlyaria (after Gude 1901c) C–D Plectopylis moellendorffi (after Gude 1901c) E–F Vn10-49, G Vn09-24 H Vn10-56, I Vn9-16, spec.1 J Vn9-16, spec.2 K–M Plectopylis verecunda, MNHN 2012-2177 (3 different specimens) N–Q G. (G.) messageri messageri (Gude, 1909) N–O Plectopylis messageri (after Gude 1909) P MNHN-IM-2012-2162, Q MNHN-IM-2012-2165 R–V G. (G.) messageri raheemi ssp. n, R 20071116C, spec.1. S–T 20071116C, spec.2. U–V 20080509C W–X Vn10-104B. Inner views: B, D, F, O; Outer views: L, T, V, X.

Figure 13.

Parietal (A, C, E, F, H, J, L, N, P, R, T, V, X) and palatal (B, D, G, I, K, M, O, Q, S, U, W, Y) plicae and lamellae of Gudeodiscus species. A–B Gudeodiscus (Veludiscus) emigrans emigrans (Möllendorff, 1901), holotype (after Páll-Gergely and Hunyadi 2013) C–D G. (V.) emigrans quadrilamellatus Páll-Gergely, 2013 (after Páll-Gergely and Hunyadi 2013) E–K G. (G.?) francoisi (Fischer, 1898) E–F holotype of Plectopylis lepida Gude, 1901 (after Gude 1901b), G MNHN-IM-2012-2311 H–I holotype of Plectopylis bavayi Gude, 1901 (after Gude 1901a) J–K Plectopylis francoisi (after Gude 1899b) L–U G. (G.) giardi giardi (Fischer, 1898) L Plectopylis giardi (after Gude 1899a) M Plectopylis giardi (after Gude 1899b) N–O Plectopylis congesta Gude, 1899 (after Gude 1899a); P–Q Vn10-69 R–S Vn10-59 T–U 2011/85 V–Y G. (G.) villedaryi (Ancey, 1888) V–W holotype of Plectopylis (Endoplon) choanomphala Möllendorff, 1901 (after Gude 1901c) X–Y Vn10-47A. Inner views: D, F, I, K, M, O, Q, S, W, Y; Outer views: B, U.

Figure 14.

Parietal (A, C, E, G, H, J, L, M, O, Q, S, U, W, X) and palatal (B, D, F, I, K, N, P, R, T, V, Y) plicae and lamellae of Gudeodiscus and Halongella gen. n. species. A–G Gudeodiscus (Gudeodiscus) dautzenbergi (Gude, 1901) A–B Plectopylis dautzenbergi (after Gude 1901a) C–D Plectopylis persimilis Gude, 1901 (after Gude 1901a) E–F Vn10-44, G Vn10-44 H–N Halongella schlumbergeri (Morlet, 1886) H–I Plectopylis jovia (after Gude 1901b) J–K Plectopylis schlumbergeri (after Gude 1901b) L MNHN-IM-2012-2481 M–N holotype of Plectopylis hirsuta Möllendorff, 1901 (after Gude 1901c) O–R H. fruhstorferi (Möllendorff, 1901) O–P after Gude (1901c) Q–R Vn11-171 S–Y G. (G.?) suprafilaris (Gude, 1908) S–T after Gude (1908) U–V 2011/81, spec.1. W 2011/81, spec.2. X–Y Vn10-125. Inner views: B, D, F, I, K, N, P, T; Outer views: R, V, Y.

Figure 15.

Parietal (A, C, E, F, H, J, L, N, O, Q) and palatal (B, D, G, I, K, M, P, R) plicae and lamellae of Gudeodiscus species. A–D Gudeodiscus (Gudeodiscus) infralevis (Gude, 1908) A–B holotype of Plectopylis infralevis (after Gude 1908) C–D Holotype of Plectopylis soror (after Gude 1908) E–G G. (G.?) cyrtochilus (Gude, 1909) E–F MNHN-IM-2012-2251 (two different specimens) G 2012/47 H–N G. (G.) fischeri (Gude, 1901) H–I Plectopylis fischeri (after Gude 1901a) J–K 20090515C L–M Vn10-120 N MNHN-IM-2012-2241 O–R G. (G.) fischeri (Gude, 1901) (identical with the holotype of tenuis) O–P after Gude (1901a) Q–R Vn10-28A (two different specimens). Inner views: B, D, I, M, P; Outer views: G, K, R.

Figure 16.

Plot of shell height against shell width (diameter) for 122 adults of Plectopylis cf. anterides/gouldingi (MNHN 2012-2133, MNHN 2012-2156, partly MNHN 2012-2218), Plectopylis cf. fallax (Vn11-187, MNHN 2012-2132, partly MNHN 2012-2218) and Plectopylis cf. fallax var. major (MNHN 2012-2155) from northern Vietnam. Samples MNHN 2012-2155 and MNHN 2012-2156 originally belonged to the same sample.

Figure 17.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) fischeri (Gude, 1901). Locality information: Tuyên Quang Province, near Ton Hông, road #185 from Tuyên Quang to Vĩnh Lộc (formerly Chiêm Hóa) (NE of Tuyên Quang), leg. Hemmen, Ch. & J., 19.03.2011. Scale represents 5 mm.

Figure 18.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) fischeri (Gude, 1901) (typical tenuis specimen). Locality information: Bắc Kạn Province, Ba Bể Nat. Park, Hang Thẳm Kit 2 km from the look-out tower, 335 m, 22°24.686'N, 105°37.710'E, leg. Hunyadi, A., 19.11.2011. Scale represents 5 mm.

Figure 19.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) giardi giardi (Fischer, 1898). Locality information: Cao Bằng Province, Quảng Uyên N, 206–207 cross, 430 m, 22°42.737'N, 106°27.223'E, leg. Hunyadi, A., 16.11.2011. Scales represents 5 mm (left) and 2 mm (right).

Figure 20.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) messageri raheemi Páll-Gergely & Hunyadi, ssp. n. Locality information: Hòa Bình Province, ca. km 156 old road Hà Nội to Sơn La (right side off road), 20°46.000'N, 104°53.885'E, leg. Hemmen, Ch. & J., 15.10.2010. Scale represents 5 mm.

Figure 21.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887) (typical fallax). Locality information: Lào Cai Province, ca. 3 km SW of Nhà Văn Hóa, 22°25.513'N, 104°12.194'E, leg. Hemmen, Ch. & J., 04.10.2011. A–B “Specimen1” C “Specimen2”. Scale represents 1 mm.

Figure 22.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887). Locality information: Lạng Sơn Province, ca. 10.6 km from Bình Gia to Lạng Sơn on road 1B, 21°53.639'N, 106°25.895'E, leg. Hemmen, Ch. & J., 01.04.2011. Scale represents 5 mm.

Figure 23.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) villedaryi (Ancey, 1888). Locality information: Thái Nguyên Province, Ðình Cả NE 4 km, Phượng Hoàng cave, around the entrance of the cave, 365 m, 21°46.782'N, 106°07.189'E, leg. Hunyadi, A., 13.11.2011. Scale represents 5 mm.

Figure 24.

Reproductive anatomy of Gudeodiscus (Gudeodiscus) villedaryi (Ancey, 1888), abnormal specimen. Locality information: Thái Nguyên Province, Võ Nhai District, Phú Thượng Commune, Phượng Hoàng Cave, Mỏ Gà Vill., ca 150 m, 21°46.836'N, 106°07.107'E, leg. Ohara, K., 20.05.2009. Scale represents 2 mm.

Figure 25.

Reproductive anatomy of Halongella fruhstorferi (Möllendorff, 1901). Locality information: Quảng Ninh Province, Vân Đồn Island (NE Cẩm Phả), Cái Rồng village, 21°3.560'N, 107°25.551'E, leg. Hemmen, Ch. & J., 14.08.2011. Scale represents 5 mm.

Figure 26.

Reproductive anatomy of Halongella schlumbergeri (Morlet, 1886), “Specimen1”. Locality information: Hải Phòng Province, Cát Bà Island, behind cemetery of Gia Luận village, 20°50.092'N, 106°58.560'E, leg. Hemmen, Ch. & J., 10.04.2011. Scale represents 5 mm.

Figure 27.

Reproductive anatomy of Sicradiscus mansuyi (Gude, 1908). Locality information: Cao Bằng Province, southern edge of Pác Rải, Trùng Khánh 3 km towards Quảng Uyên, left side of the road, 570 m, 22°48.961'N, 106°30.533'E, leg. Hunyadi, A., 28.05.2012. Scale represents 2 mm.

Figure 28.

Inner walls of the penis of Gudeodiscus Páll-Gergely, 2013 species. A Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887) (typical fallax specimen, for locality see Figure 21) B Gudeodiscus giardi giardi (Fischer, 1898) (for locality see Figure 19) C G. (G.) phlyarius (Mabille, 1887) (for locality see Figure 22) D G. (G.) fischeri (Gude, 1901) (for locality see Figure 17) E G. (G.) messageri raheemi Páll-Gergely & Hunyadi, ssp. n., 20080510A F–G G. (G.) villedaryi specimens collected at the same locality in two different dates: F November (2011/102) and G May (20090520A). All photos by B. Páll-Gergely.

Figure 29.

Inner walls of male reproductive organs of Gudeodiscus and Halongella gen. n. species. A–B penis of Halongella schlumbergeri (Morlet, 1886), 20071122D C penis of Halongella fruhstorferi (Möllendorff, 1901) (for locality see Figure 25) D epiphallus of Gudeodiscus fischeri (Gude, 1901), (for locality see Figure 18) E epiphallus of Gudeodiscus giardi giardi (Fischer, 1898), (for locality see Figure 19) F penial caecum of G. (G.) messageri raheemi Páll-Gergely & Hunyadi, ssp. n. (for locality see Figure 20) G penial caecum of G. (G.) messageri raheemi ssp. n. (for locality see Figure 28E) H epiphallus of H. schlumbergeri (for locality see Figure 26) I H. fruhstorferi, (for locality see Figure 25) J spermatophore of G. (G.) fischeri, (for locality see Figure 17). All photos by B. Páll-Gergely.

Figure 30.

Calcareous claws found in pockets on the inner penial wall of Gudeodiscus and Halongella gen. n. species. A–C, F Gudeodiscus (Gudeodiscus) villedaryi (Ancey, 1888) (for locality see Figure 23) D Gudeodiscus giardi giardi (Fischer, 1898) (for locality see Figure 19) E G. (G.) fischeri (Gude, 1901) (for locality see Figure 19) G–I Halongella schlumbergeri (Morlet, 1886) (for locality see Figure 29A–B). The claws in case of G. (G.) fischeri and H. schlumbergeri were too fragile for dissecting out, therefore drawings are presented. All images by B. Páll-Gergely.

Figure 31.

Inner wall of the vagina of Sicradiscus and Gudeodiscus species. A Sicradiscus mansuyi (Gude, 1908), (for locality see Figure 27) B Gudeodiscus (Gudeodiscus) messageri raheemi Páll-Gergely & Hunyadi, ssp. n. (for locality see Figure 20) C Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887), Vn11-157 D Gudeodiscus (Gudeodiscus) fischeri (Gude, 1901) (for locality see Figure 17).

Figure 32.

Inner wall of the vagina of Halongella gen. n. and Gudeodiscus species. A–B Halongella fruhstorferi (Möllendorff, 1901), red circles indicate calcareous granules (for locality see Figure 25) C Gudeodiscus (G.) giardi giardi (Fischer, 1898) (for locality see Figure 19) D G. (G.) villedaryi (Ancey, 1888) (for locality see Figure 24).

Figure 33.

Inner wall of the vagina (A–B, F–G) and vaginal granules (C–E) of Halongella schlumbergeri (Morlet, 1886). “Specimen1” (gravid specimen, locality Vn11-172): B, F; “Specimen2” (not gravid specimen, locality 20071122D): A, C–E, G.

Figure 34.

SEM images of radulae of Gudeodiscus species. A, D, G, J, M show the middle part of the radula B, E, H, K, N show the central tooth and the first 2–3 pairs of laterals C, F, I, L, O show the marginals. A–C Gudeodiscus (Veludiscus) emigrans otanii Páll-Gergely & Hunyadi, 2013, China, Guangxi, Yizhou Shi, Aishan Xiang, Xiannuyan, ca 170 m, 24°29.292'N, 108°34.057'E, leg. Nakahara, Y., Ohara, K., Okubo, K. & Otani, J. U., 13.11.2004. D–F G. (V.) eroessi eroessi Páll-Gergely & Hunyadi, 2013, China, Guangxi, Guigang Shi, Guzhang Xiang, beyond Chuanshan village, ca 155 m, 23°20.848'N, 109°19.256'E, leg. Nakahara, Y., Ohara, K., Okubo, K. & Otani, J. U., 09.11.2004 G–I G. (V.) okuboi Páll-Gergely & Hunyadi, 2013, Guangxi, Guigang Shi, Guzhang Xiang, road to Wushan Xiang, ca 130 m, 23°21.178'N, 109°17.432'E, leg. Nakahara, Y., Ohara, K., Okubo, K. & Otani, J. U., 09.11.2004. J–L G. (V.) pulvinaris pulvinaris (Gould, 1859), China, Hong Kong Peak, leg. Miu Yeung, June 2013 M–O G. (G.) fischeri (Gude, 1901), (for locality see Figure 17). All photos by B. Páll-Gergely.

Figure 35.

SEM images of radulae of Gudeodiscus species. A, D, G, J, M show the middle part of the radula B, E, H, K, N show the central tooth and the first 2–3 pairs of laterals C, F, I, L, O show the marginals. A–C Gudeodiscus (Gudeodiscus) giardi giardi (Fischer, 1898) (for locality see Figure 19) D–F G. (G.) messageri raheemi Páll-Gergely & Hunyadi, ssp. n. (for locality see Figure 20) G–I G. (G.) multispira (Möllendorff, 1883), China, Guangxi, Qingshan, Qingshan Zhen, Lipu Xian, ca 250 m, 24°26.189'N, 110°20.008'E, leg. Nakahara, Y., Ohara, K., Okubo, K. & Otani, J. U., 12.11.2004. J–L G. (G.) phlyarius (Mabille, 1887), Lạng Sơn Province, ca. km. 50 of road 1B, 10 km to Bình Gia, 21°53.911'N, 106°25.664'E, leg. Hemmen, Ch. & J., 01.04.2011. M–O G. (G.) villedaryi (Ancey, 1888), (for locality see Figure 23). All photos by B. Páll-Gergely.

Figure 36.

SEM images of radulae of Halongella and Sicradiscus species. A, D, G, J, M show the middle part of the radula; B, E, H, K, N show the central tooth and the first 2–3 pairs of laterals C, F, I, L, O show the marginals. A–C Halongella fruhstorferi (Möllendorff, 1901) (for locality see Figure 25) D–F H. schlumbergeri (Morlet, 1886) (for locality see Figure 29A–B) G–I Sicradiscus invius (Heude, 1885), China, Sichuan, Dujiangyan Shi, Taian Zhen, Sanlong Shuijingrongdong, ca 1090 m, 30°55.039'N, 103°29.662'E, leg. Hosoda, T., Ohara, K., Okubo, K., Otani, J. U., 17.09.2013. J–L S. mansuyi (Gude, 1908), (for locality see Figure 27) M–O S. schistoptychia (Möllendorff, 1886), China, Hunan, Yongzhou Shi, Ningyuan Xian, Jiuyishan Yaozuxiang, Jiuyishan Guojia Senlin Gongyuan, old maple forest, 25°21.200'N 111°58.696'E, 450 m, leg. Hunyadi, A., 11.11.2010. All photos by B. Páll-Gergely.

Figure 37.

SEM images of radulae of Sicradiscus and Sinicola species. A, D, G, J, M show the middle part of the radula B, E, H, K, N show the central tooth and the first 2–3 pairs of laterals C, F, I, L, O show the marginals. A–C Sicradiscus transitus Páll-Gergely, 2013, Guangxi, Hechi Shi, Tiane Xian, Qimu Xiang, near Lahaoyan, 650 m, 24°51.359'N, 107°11.407'E, leg. Hunyadi, A. & Szekeres, M., 12.09.2013. D–F Sinicola asamiana Páll-Gergely, 2013, Sichuan, Dujiangyan Shi, Qingchengshan Zhen, Jinbian Yan, 30°55.234'N, 103°29.483'E, 930 m, leg. Hosoda, T., Ohara, K., Okubo, K., Otani, J. U., 16.09.2013. G–I S. emoriens (Gredler, 1881), Hunan, Yongzhou Shi, Lingling Qu, Dengjiachong, rocky wall, 125 m, 26°13.808'N, 111°35.907'E, leg. Hunyadi, A., 8.11.2010. J–L S. fimbriosa (von Martens, 1875), China, Hunan, Hengyang Shi, Nanyue Qu, Yuelin Xiang, southern part of Heng Shan, Chuanyan Shilin, near Ban Shanting, 590 m, 27°16.435'N 112°42.195'E, leg. A. Hunyadi 20.10.2010. M–O S. jugatoria (Ancey, 1885), China, Hubei, Yichang Shi, Changyang Tujiazu Zizhixian, Qingjiang Hualang Fengjingqu, Geheyan Shuiku, Wuluozhougli Shan, 260 m, 30°25.805'N 110°59.254'E, leg. A. Hunyadi 31.10.2010. All photos by B. Páll-Gergely.

Figure 38.

SEM images of radulae of Sinicola species. A, D, G show the middle part of the radula B, E, H show the central tooth and the first 2–3 pairs of laterals C, F, I show the marginals. A–C Sinicola murata (Heude, 1885), Sichuan, Dujiangyan Shi, Qingchengshan Zhen, Jinbian Yan, 30°55.234'N, 103°29.483'E, 930 m, leg. Hosoda, T., Ohara, K., Okubo, K., Otani, J. U., 16.09.2013. D–F S. reserata azona (Gredler, 1887), Guizhou, Tongren Shi, Wanshanchen dirt road, Xianrendong, ca 865 m, 27°31.785'N, 109°13.008'E, leg. Ohara, K., Okubo, K. & Otani, J. U., 10.5.2010. G–I S. stenochila (Möllendorff, 1885), Hubei, Enshi Tujiazu Miaozu Zizhizhou, Badong Xian, Badong E, Bashan Senlin Gongyuan, 300 m W from the entrance, 220 m, 31°01.684'N, 110°25.094'E, leg. Hunyadi, A., 3.11.2010. All photos by B. Páll-Gergely.

Figure 39.

Locations mentioned in literature on plectopylid taxonomy. 1 Muong-Bo 2 Phony-Tho 3 Trinh-Thuong 4 Muong-Hum 5 Nat-Son (Nhat Son) 6 Muong-Kong 7 Long-Ping 8 Pac-Kha 9 Ha-Giang 10 Tinh-Tuc 11 Cao-Bang 12 Déo-Ma-Phuc 13 Quang-Huyen 14 Ha-Lang 15 Cho-Ra 16 Bac-Khan 17 Nac-Ri 18 That-Khé 19 Cho-Moi 20 Lang-Son 21 Mansongebirge 22 Than-Moi 23 Bac-Ninh 24 Dong-Trieu 25 Bah-Mun 26 Kebao 27 Baie d’Along. The locations of “Col de Nuages” (Clouds Pass) could not be located. It is probably situated on Lao Kay Province, close to Muong-Hum.

Figure 40.

Distribution of Gudeodiscus, Halongella gen. n. and Sicradiscus species. Legends: empty circle: Halongella schlumbergeri (Morlet, 1886), star (close to the circles): H. fruhstorferi (Möllendorff, 1901), empty triangle: Gudeodiscus (Gudeodiscus) dautzenbergi (Gude, 1901), filled triangle G. (G.) villedaryi (Ancey, 1888), empty square: G. (G.) anceyi (Gude, 1901), filled circle: Sicradiscus mansuyi (Gude, 1908).

Figure 41.

Distribution of Gudeodiscus species. Legends: filled circle: Gudeodiscus (Gudeodiscus?) suprafilaris (Gude, 1908), triangle: G. (G.) fischeri (Gude, 1901), empty square: G. (G.?) cyrtochilus (Gude, 1909).

Figure 42.

Distribution of Gudeodiscus species. Legends: filled triangle: Gudeodiscus (Veludiscus) emigrans quadrilamellatus Páll-Gergely, 2013, empty circle: G. (G.) giardi giardi (Fischer, 1898), filled circle: G. (G.?) francoisi (Fischer, 1899), semi filled circle: co-occurrence of the latter two species.

Figure 43.

Distribution of Gudeodiscus Páll-Gergely, 2013 species. Legends: filled triangle, top down: typical Gudeodiscus (Gudeodiscus) phlyarius (Mabille, 1887), filled triangle, top up: “Gudeodiscus phlyarius werneri Páll-Gergely, 2013” (synonym of phlyarius); empty triangle, top up: G. (G.) phlyarius populations showing transitional characters towards werneri in terms of shell shape; empty triangle, top down: atypical G. (G.) phlyarius; empty circle: Gudeodiscus messageri raheemi ssp. n., filled circle: G. (G.?) hemmeni sp. n. (in all localities it co-occurs with G. (G.) messageri raheemi ssp. n.); circle with filled triangle in the middle: co-occurrence of G. (G.) messageri raheemi ssp. n. and atypical G. (G.) phlyarius. The shaded area indicates the area inhabited by G. (G.) messageri messageri (Gude, 1909) and “anterides”, “fallax” and “gouldingi”-like populations of G. (G.) phlyarius. Filled square indicates the position of Phong-Tho, the type locality of Plectopylis verecunda Gude, 1909 (synonym of G. phlyarius). Numbers 1–3 refer to atypical populations assigned to G. (G.) phlyarius. For explanation, see text.

Figure 44.

Shell widths of Halongella schlumbergeri (mm) in the Halong Bay Area.

Figure 45.

Living specimens of Gudeodiscus (Gudeodiscus) giardi giardi (Fischer, 1898) (A), Cao Bằng Province, Hòa An District, Nguyễn Huệ Commune, small hill just outside of Khau Trang Village, 22°33.510'N, 106°10.294'E, leg. Naggs, F. et al. 22.06.2011.; and Halongella schlumbergeri (Morlet, 1886) (B), Halong Bay area, Vietnam. Photos: F. Naggs.

Identification key to Vietnamese and Chinese plectopylid genera

1 body whorl keeled 2
body whorl rounded 3
2(1) anterior lamella absent or present as small denticles Sinicola
anterior lamella present Sicradiscus
3(1) shell smaller than 9 mm, smooth at its base, and has a strong apertural fold Sicradiscus
shell larger than 9 mm; if it is smaller than 12 mm and smooth, then it has no apertural fold 4
4(3) inner penial wall with distinct pockets standing in 1 or 2 rows 5
inner penial wall with parallel folds without large pockets Halongella
5(4) penial retractor simple Gudeodiscus (G.)
penial retractor is covered with additional muscle fibres which attach on the distal end of the penis Gudeodiscus (Veludiscus)

Identification key to Vietnamese species (regardless of generic association)

1 shell smaller than 12 mm 2
shell larger than 12 mm 5
2(1) apertural fold well visible 3
apertural fold missing or inconspicuous, very weak cyrtochilus
3(2) ventral surface smooth, glossy mansuyi
ventral surface sculptured 4
4(3) free plicae above and below the anterior lamella absent anceyi
upper and lower plicae free from the anterior lamella hemmeni sp. n.
5(1) dorsal reticulate and ventral smooth areas change abruptly suprafilaris
dorsal and ventral sculpture do not change abruptly 6
6(5) parietal wall with a single lamella 7
parietal wall with two lamellae (or the anterior lamella is dissolved into small denticles) 10
7(6) anterior to the parietal lamella there are four parallel horizontal plicae e. quadrilamellatus
anterior to the lamella there are two horizontal plicae, one above, one below 8
8(7) shell about 13–14 mm fruhstorferi
shell larger than 15 mm 9
9(8) shell strongly-built, seemingly smooth, callus elevated schlumbergeri
shell relatively thin, regularly ribbed, callus weak e. emigrans
10(6) shell thin-walled, callus weak, sculpture weak, rather glossy 11
shell more strongly-built, callus strong 12
11(10) shell flat or nearly flat, umbilicus wide fischeri
spire somewhat elevated, umbilicus rather narrow infralevis
12(10) umbilicus very narrow, dorsal surface domed 13
umbilicus moderately narrow, dorsal surface moderately domed 14
13(12) shell yellowish, callus blunt, rather low francoisi
shell brownish, callus very much elevated, high, rather sharply defined giardi
14(12) shell regularly ribbed, rather thin walled 15
shell thick walled, strongly built 17
15(14) anterior lamella usually free from the lower plica phlyarius
anterior lamella in contact with the lower plica, or the lower plica is dissolved into denticles 16
16(15) anterior lamella is in contact with the lower plica, lower plica do not extend beyond the lamella in anterior direction messageri messageri
anterior lamella dissolved into small denticles; or if not dissolved, the lower plica extends beyond the lamella in anterior direction messageri raheemi ssp. n.
17(14) apertural fold horizontal schlumbergeri
apertural fold oblique 18
18(17) additional lower plica present under the lamellae villedaryi
additional lower plica absent under the lamellae dautzenbergi

Taxonomic positions of the genera Gudeodiscus, Halongella gen. n., Sicradiscus and Sinicola

The “Eastern Plectopylidae” (see Páll-Gergely and Hunyadi 2013), namely taxa inhabiting China, Vietnam, Taiwan and Okinawa (Japan) are conchologically relatively diverse. Their common features are the ribbed protoconch and the absence of the long parietal horizontal plica. The genus Endothyrella, which mainly inhabits north-eastern India also shares these features with the genera of “Eastern Plectopylidae”. Therefore Endothyrella is possibly a close relative to the genera Gudeodiscus, Halongella gen. n., Sicradiscus and Sinicola. The genera of “Western Plectopylidae” (Endoplon, Chersaecia and Plectopylis) have smooth but matt or “tuberculated” embryonic whorls and usually long horizontal parietal plicae (a main plica and a lower plica) which run to the peristome. Some Endothyrella species have long lower and main plicae, but these may not be homologous with those in the Chersaecia and Plectopylis. Some species which have been assigned to the genus Chersaecia (andersoni W. Blanford, 1869, laomontana L. Pfeiffer, 1863, oglei, serica, munipurensis) also possess ribbed protoconchs. These probably do not belong to any of the genera mentioned herein, and their taxonomic status require revision.

In the revision of the Chinese Plectopylidae (Páll-Gergely and Hunyadi 2013), three genera were recognized, namely Gudeodiscus, Sicradiscus and Sinicola. The most important shell characters for recognition of Sinicola are the following: body whorl keeled; periostracal folds usually present on the keel; apertural fold almost always absent; the anterior parietal lamella is absent or present only in some small, separate denticles. Gudeodiscus exhibits the following characters: body whorl rounded; periostracal folds absent; apertural fold often present; anterior parietal lamella often present. Both genera inhabit restricted geographical areas with minor overlaps; Sinicola ranges from Middle Sichuan to northern Guangxi, Guangdong and eastern Hunan, whereas Gudeodiscus ranges from northern Vietnam to southern Hunan and southern Guangdong. Reproductive anatomical investigations (Páll-Gergely and Hunyadi 2013, Páll-Gergely and Asami 2014) found that Sinicola species exhibit a ribbed inner penial wall with a few tiny calcareous granules. The ribs are more prominent in the distal part of the penis or continuous until the atrium but this varies between individuals. Examples of Gudeodiscus usually also have parallel folds, but they have characteristic small pockets arranged in one or two more or less straight transverse lines in the distal penis. These pockets contain calcareous granules, probably only during the mating period (see discussion on anatomy and biology). The genus Gudeodiscus is divided into two groups based on the morphology of the distal penis-penial caecum-retractor muscle complex. In one type, the epiphallus is slender, cylindrical, and addition to the retractor muscle, which attaches on the penile caecum, several muscle fibres attach to the penis itself. In the other type the epiphallus has a somewhat thickened proximal part, and has no additional muscle fibres attached to the penis (Páll-Gergely and Hunyadi 2013, Páll-Gergely and Asami 2014). It may not be legitimate to subdivide the genus on the basis of this anatomical difference, when the shell characters do not show clear distinction (Páll-Gergely and Asami 2014). For example, G. eroessi (first type) and G. multispira (second type) are conchologically very similar. However, we found that radula traits distinguish between them as well as the genital anatomy does. Therefore we find it well supported to separate these two groups into different subgenera (Gudeodiscus and Veludiscus subgen. n.).

The taxonomic position of the species classified within Sicradiscus is problematic. Sicradiscus was erected for several, small bodied species which inhabit a large area ranging from Sichuan to Okinawa, Japan. There is continuous variation across the genus Sicradiscus in terms of shell characters. Sicradiscus invius, S. securus, S. mansuyi and S. feheri have a rounded body whorl and possess a strong apertural fold. In contrast, Sicradiscus schistoptychia, S. diptychia, S. cutisculptus, S. ishizakii and S. hirasei have a shouldered body whorl and lack the apertural fold. The two groups are within the same genus because Sicradiscus transitus is similar to S. schistoptychia in possessing divided palatal plicae and a keeled body whorl, at the same time having a strong apertural fold similar to that of S. feheri. Moreover, S. transitus ranges between S. feheri and S. schistoptychia geographically. The present and a previous study (Páll-Gergely and Asami 2014) revealed that the inner morphology of the penis in S. schistoptychia is similar to that of Sinicola, whereas S. invius, S. mansuyi and S. transitus are similar to Gudeodiscus in that trait. Separating some Sicradiscus species into Gudeodiscus and others in Sinicola based on the penial morphology does not resolve their taxonomy because of the large conchological similarity among Sicradiscus species. An alternative classification might be to place all Gudeodiscus, Sicradiscus and Sinicola species into one genus because of the transitional features of Sicradiscus between Sinicola and Gudeodiscus. However, our study does not support this because both Sinicola and Gudeodiscus show clear synapomorphic characters and signs of their separate major radiations in different geographic areas. The most possible explanation is that Sicradiscus species represent basal lineages within the GudeodiscusSicradiscusSinicola complex, in which others diverged into the two lineages, one with the keeled body whorl and folded penial wall and the other with the rounded body whorl and pocketed penial wall. Sicradiscus species may probably have undergone only slight conchological changes. This hypothesis is supported by the geographic distribution of most Sicradiscus species, roughly between the areas of Gudeodiscus and Sinicola.

Plectopylis schlumbergeri and P. fruhstorferi had parallel folds on the inner penial wall and calcareous granules were found between the parallel folds all along the penis. In both subgenera of the genus Gudeodiscus however, the pockets for calcareous granules are arranged in one or two rows, and they are absent elsewhere. Based on this morphological character, they are moved to a new genus, Halongella. Additionally, Halongella gen. n. species lack a penial caecum, which was found in the majority of Gudeodiscus species.

Anatomy and biology

Stoliczka (1871) described the organ proximal to the gametolytic sac of Plectopylis as “a shorter, more muscular gland which appears to represent the arrow or amatorial gland”. Pilsbry (1894) noted this as “an organ of unknown homology, either a dart sack, a diverticulum of the spermatheca or an appendicula”. A spermatophore was found inside this organ of Gudeodiscus fischeri. This suggests that the organ is a diverticulum, starting from the wall of the distal end of the vagina/beginning of pedunculus. In most stylommatophoran land snails the diverticulum derives from the stalk of the gametolytic sac. The only exception known before this study was the subfamily Garniierinae (family Clausiliidae), in which the diverticulum derives from the pedunculus (Szekeres 1998).

The inner walls of the male genital organs, especially the penis, show a large diversity across the genera Gudeodiscus, Halongella gen. n., Sicradiscus and Sinicola. Sinicola and Halongella gen. n. have parallel folds on the inner penial wall, occasionally with tiny, usually flat calcareous granules, often without characteristic shapes. The penial wall of Gudeodiscus species is usually also characterized by folds, but also pockets arranged in one or two rows in the distal part of the penis. The rows can be straight (e.g. G. giardi and G. villedaryi), can follow a bell-shaped line (G. fischeri), or waves (G. messageri raheemi ssp. n.) on the opened penal wall. Sicradiscus species have both types of penial sculpture (with and without pockets) (Páll-Gergely and Asami 2014, and this study). In most Gudeodiscus specimens the granules are hook or claw-like, and each of them is placed within a pocket on the wall of the head of the penis. Two dissected specimens of Gudeodiscus phlyarius (typical fallax specimens), however, had flat, oval granules within the penial pockets. It is not clear whether this shape of granules is stable throughout the life span or dependent on season or age. In the revision of the Chinese species (Páll-Gergely and Hunyadi 2013) we described that calcareous hooks are easily removable from the folds in the penial internal wall. In the case of Vietnamese specimens (G. giardi, G. fischeri and G. villedaryi), however, the claws were attached into the wall inside the pocket and were difficult to remove. The SEM images of removed claws revealed that the base of each claw, which was buried into the pocket wall, is granulated in the surface, whereas the exposed tip of each claw was smooth. The hooks from the penis lumen of Chinese Gudeodiscus phlyarius (figured specimen in Páll-Gergely and Hunyadi 2013) dissolved with no remains in 90% lactic acid. Thus, these granules may consist of calcium carbonate.

The penial claws or hooks known in other stylommatophoran families (e.g. Zonitidae s.l., Streptaxidae, Cryptazeca) do not seasonally disappear and are fixed to the internal wall, because to our knowledge, hook-less specimens have not been reported in contrast to those in Plectopylidae (see also Páll-Gergely and Hunyadi 2013). Those of Cryptazeca and Streptaxidae are not calcareous (Visser 1973, Verdcourt 1979, 1985, Gómez 1991), whereas Zonitidae have calcareous claws (Schileyko 2003). The hook-like granules of Gudeodiscus and the minute, flat, or sometimes elongated or globular granules of other plectopylid genera may have similar roles but a different origin from the fixed claws of other Stylommatophora.

In some Gudeodiscus specimens the proximal (lower) part of the penial wall is ornamented with longitudinal folds only, but in others it has transverse and dense wrinkles (e.g. in G. giardi giardi and in one specimen of G. villedaryi). The transverse and longitudinal arrangement may result in a reticulated surface of the inner penial wall, such as those in G. phlyarius (fallax-like specimens). These traits need to be used for taxonomy with careful attention to collection dates and instead may provide opportunities for studies of functional roles for reproductive success for the following reason: two specimens of G. villedaryi collected in different periods of the year (20 May and 12 November) from the same locality greatly differed in these traits. The one collected in May was gravid, and its penis had only longitudinal folds on its inner wall, with slightly waved proximal portions of the folds. In contrast, a specimen collected in November was not gravid and had conspicuous, dense and transversal folds on the proximal portion of the inner wall of the penis. This transversal folded structure turned suddenly to a longitudinal folded area with calcareous claws between the pockets. This result suggests that the morphology of fine sculpture of the inner penial wall (at least inside the proximal half of the penis) may be seasonally variable. The gravid individual may have lost hooks in a mating period before collected in May. The latter individual with no embryo may have been in a period for copulation. Our observation suggests that the penial internal wall may be restructured to regenerate the hook-like calcareous claws for copulation. Further studies are necessary to test this hypothesis.

The other organs of male genitalia, penial caecum and epiphallus have generally a simpler inner surface, usually with parallel and longitudinal folds, than the penis. In smaller species it is difficult to open these very slim organs, especially the epiphallus. The longitudinal folds on the inner wall of the epiphallus of Halongella gen. n. species have perpendicular projections which overlap with those of the neighbouring fold. Besides this, all other species have an epiphallus with simple internal longitudinal folds. The inner wall of the penial caecum is also ornamented by longitudinal folds, which are sometimes wavy, and form hollows with the neighbouring fold. This structure is similar to the penial sculpture of Sinicola species. A function of these hollows would probably be to hold the small calcareous granules. In some species the sculpture of the penial caecum is more complex; Gudeodiscus messageri raheemi has deep sinuses with the calcareous granules. Gudeodiscus giardi giardi has pockets formed by two neighbouring papillae (Páll-Gergely and Asami 2014). The calcareous granule within the caecum can be elongated or globular without any characteristic shape, such as in one of the dissected G. messageri raheemi specimens, or the granules can be hook-like, similar to, but smaller than those found in the penial lumen, such as in a specimen of G. pulvinaris pulvinaris (see Páll-Gergely and Asami 2014).

Specimens that were fixed in 70% ethanol were used for this investigation. Thus, at this stage of study, we are not able to rule out a possibility that some of the granules appeared as observed because of the process of preservation. However, hook structure corresponds to pocket structure in the penial internal surface. Each hook is regularly located in a pocket in a determined orientation. Further, they exhibit a taxonomically characteristic and sophisticated shape. For these reasons, the presence of hooks and granules in the present family cannot be ascribed to an artefact during preservation.

The absence of embryos in the uterus was statistically significantly associated with the presence of calcareous granules inside the penis, within Gudeodiscus (p = 0.0001) and also across all the four genera (p = 0.0006) (Tables 3, 4, 5). This strongly suggests that these granules may function as a disposable male mating apparatus. These granules disappear perhaps through repeated copulation in a mating season. It could require some time to gain the granules again if they lose granules and bear offspring. Thus, for some time during the mating season, they might remain with no granules before embryos develop. If so, these would exhibit no granules or embryos. However, this was the case only in three of 34 specimens examined in this study. Our results illuminate the importance of further studies on their reproductive life history and the ecological function of these granules.

The function of the calcareous hooks and granules inside the penis are unknown, although they probably play some role as a mating apparatus as well as the non-calcareous hooks in other groups. It has been classically postulated that these may function for mechanical stimulation for mating success like other penial structures or darts (Tompa 1984; Atkinson and Atkinson 1987). However, later studies have shown that love darts are not for physical stimulation but to inject mucus which includes a substance that increases paternity by inducing reconfiguration of partner’s organs for spermatophore digestion (Koene and Chase 1998; Chase and Blanchard 2006; Kimura et al. 2014). Separately, De Winter et al. (1999) proposed that the spines on the penial wall play a role in the process of spermatophore formation in the streptaxid genus Sinistrexcisa. This is probably not the case in Plectopylidae, because they have the structurally distinguishable epiphallus. Their spermatophores are formed in this organ instead of the penis, and thus the structure of parallel inner folds in the epiphallus matches the morphology of spermatophore. Tompa (1984) also suggested that the penial hooks may function as mechanical holdfasts during mating. The present study provides a systematic ground for further studies on the evolution of mating apparatus inside the penis.

The function of the characteristic vaginal granules in one of the Halongella schlumbergeri specimens are also unknown. To our knowledge, no disposable granules have been reported in land snails which are attached to the vagina wall. The presence of vaginal granules in a non-gravid specimen and the presence of “vaginal sand” in a gravid specimen indicate that these granules are present only seasonally, probably related to the mating period. The characteristic shape of the granules, namely the flat base portion and the needle-bearing apical part does not support the hypothesis that they are artefacts formed during preservation.

To our knowledge, information on plectopylid radulae was published by Stoliczka (1871; Plectopylis achatina, P. cyclaspis and Endothyrella pinacis), Solem (1966; Chersaecia simplex) and Chang and Ookubo (1999; Sicradiscus ishizakii). Here we publish the radula morphology of 23 Chinese and Vietnamese species. Our limited information suggests that the relative size of the central tooth and the shape of the marginal teeth may be used in the systematics of the family. The genera Sicradiscus, Sinicola and the subgenus Gudeodiscus have relatively large central tooth (as large as or larger than the ectocone of the first laterals), and their marginal teeth are tricuspid with pointed cusps and deep incision between the cusps. In contrast, Plectopylis, Halongella gen. n., and Gudeodiscus (Veludiscus) subgen. n. possess smaller central tooth than the ectocone of the first lateral, and their marginals are bicuspid, or even if they are tricuspid, the innermost cusp is blunt and small, and there is a shallow incision between the inner two cusps. Stoliczka (1871) mentioned that Endothyrella pinacis (that time Plectopylis pinacis) has a larger central tooth than the two Plectopylis species, but did not provide a description or drawing of the marginal teeth. The description of the radula of Chersaecia simplex by Solem (1966) is accurate but he did not publish drawings. In that species, the central tooth is “tiny”, supposedly smaller than the ectocones of the first laterals. The ectocones of the outer marginals are “reduced and split” (= marginals are tricuspid). This information on the marginals, however, is insufficient to allow comparison with our data.

Habitat

Plectopylid species seem to be associated with calcareous areas. Living specimens occur at the base of large limestone rocks surrounded by leaf litter and humus. Thus, they are not rock-dwelling but ground-dwelling. Most living species have reticulated sculpture on the dorsal shell side, which is often covered with soil and this may be of value in providing camouflage.

Geographical coverage of the Vietnamese plectopylid fauna

At the beginning of the 20th Century all the available information on the distribution and taxonomy of Plectopylidae came with specimens from northern and eastern part of northern Vietnam (Tonkin) (Figure 39). We were able to examine only a few newly collected northern Tonkinese samples. Therefore, our knowledge on those species reported from the northern border region of Vietnam is mainly based on museum specimens. On the other hand, we examined several newly collected samples from the eastern part of northern Vietnam (Tonkin). Almost all of these specimens were identified to hitherto known species. Most of these species were found in several localities. Thus, this study covered the taxonomic diversity of plectopylids in the eastern Tonkinese area relatively well. Plectopylid specimens from western Tonkin have been examined for the first time. This resulted in the present description of a new species and a new subspecies.

Little information on plectopylid diversity has been obtained in the lowlands of the Red River, although these areas may not provide suitable habitats for land snails that prefer limestone outcrops or mountainous areas. Molluscan fauna in the border region of Sơn La and Yên Bái Provinces (Phan Xi Păng= “Farsipan” Mountain and its vicinity) is nearly unknown, maybe due to their high abundance in the limestone-free bedrock. Humid mountain forests there, however, may provide suitable habitats for plectopylids.

The southernmost Vietnamese county where plectopylids have been recorded is Nghệ An. The southern part of Vietnam may have been less intensively studied than the northern area (Tonkin). Accordingly the southernmost distribution of the family remains undetermined.

Acknowledgements

We are very grateful to all colleagues, who in various ways contributed to our revision. Colleagues who provided shell and alcohol material: Kanji Okubo, Kenji Ohara, Jamen Uiriamu Otani, Miu Yeung, Christa and Jens Hemmen, Jozef Grego and Wim J. M. Maassen; provided information, sent museum material or pictures: Philippe Bouchet and Virginie Héros (MNHN), Harold Taylor (NHM), Rose Sablon (RBINS), Sigrid Hof (SMF), Tyjuana Nickens and Robert Hershler (USNM), Gábor Majoros (Szent István Egyetem, Budapest), Tom Schiøtte (ZMUC); opened access to their museum collections: Anita Eschner (NHMW), Eike Neubert, Ronald Janssen (SMF), Ana-Maria Păpureanu (NHMS), Zoltán Fehér (HNHM); provided helpful discussions: Miklós Szekeres, Anatoly Schileyko; helped in producing Figure 16: Attila Lengyel. We are also grateful to Eike Neubert (Naturhistorisches Museum, Bern), Josef Harl (NHMW) and Tamás Deli (Munkácsy Mihály Múzeum, Békéscsaba) for taking photos of shells, to Koji Tojo (Shinshi University, Matsumoto) for help for SEM photos, and to Ben Rowson and Bram Breure for their comments on the manuscript. We are indebted to The Biodiversity Heritage Library for the multitude of rare literature made available to us (www.biodiversitylibrary.org). This study was supported by scholarships from Japan Student Services Organization and Mitsubishi Corporation to BPG and Grants-in-Aid from Japan Society for the Promotion of Science to TA.

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