Halongella fruhstorferi ( Moellendorff , 1901)

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 : 44-48

Taxon classification Animalia Stylommatophora Plectopylidae

Halongella fruhstorferi ( Moellendorff, 1901) Figures 7D, 9O, 14 O–R, 25, 29C, 29I, 32 A–B, 36 A–C

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

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

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

Gudeodiscus fruhstorferi , - Páll-Gergely & Hunyadi 2013, 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, 32 A–B, 36 A–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 14 O–R).

Measurements

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

Differential diagnosis.

Halongella fruhstorferi and Halongella schlumbergeri are congeneric based on similarity of genital morphology. Halongella fruhstorferi is smaller than Halongella schlumbergeri , having a more fragile, lighter shell and weaker apertural lip and apertural fold. In shape, Halongella fruhstorferi resembles Gudeodiscus fischeri . However, Halongella 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 ( Gudeodiscus anceyi , Gudeodiscus hemmeni sp. n., Gudeodiscus 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, 32 A–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 32 A–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 36 A–C.

Distribution

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