Gudeodiscus (Gudeodiscus?) francoisi (Fischer, 1898)

Pall-Gergely, Barna, Hunyadi, Andras, Ablett, Jonathan, Lương, Hao Văn, Fred Naggs, & Asami, Takahiro, 2015, Systematics of the family Plectopylidae in Vietnam with additional information on Chinese taxa (Gastropoda, Pulmonata, Stylommatophora), ZooKeys 473, pp. 1-118 : 18

Taxon classification Animalia Stylommatophora Plectopylidae

Gudeodiscus (Gudeodiscus?) francoisi (Fischer, 1898) Figures 7 A–C, 13 E–K

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

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

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

Plectopylis (Endoplon) francoisi , - Gude 1899c, Science Gossip, 4: 148.

Plectopylis (Endoplon) francoisi , - Gude 1899d, Science Gossip, 6: 175.

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

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

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

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

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

Gudeodiscus lepidus , - Páll-Gergely & Hunyadi 2013, 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 13 E–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 Gudeodiscus giardi giardi . In the type locality of francoisi ( Déo-Ma-Phuc, see Figure 39) the species lives together with Gudeodiscus 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 Gudeodiscus francoisi . The two holotypes are identical in shell shape and arrangement of the inner lamellae. The only difference is that the holotype of Gudeodiscus 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 Gudeodiscus 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 Gudeodiscus 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 Gudeodiscus francoisi , the former is treated as a junior synonym of Plectopylis francoisi .