Sicradiscus mansuyi (Gude, 1908)

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 : 62-68

Taxon classification Animalia Stylommatophora Plectopylidae

Sicradiscus mansuyi (Gude, 1908) Figures 2A, 9H, 11 A–B, 27, 31A, 36 J–L

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

Sicradiscus mansuyi , - Páll-Gergely & Hunyadi 2013, 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 11 A–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 Sicradiscus transitus is in contact with both the upper and the lower plicae, which are free from the lamella in Sicradiscus 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 Sicradiscus mansuyi . Gudeodiscus anceyi is larger and has a ribbed shell with spiral lines on the whole shell. Species possessing a glossy ventral surface ( Gudeodiscus cyrtochilus , Gudeodiscus 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 Sicradiscus 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 36 J–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.