Angustopila cicatricosa Pall-Gergely & Vermeulen, 2023

Pall-Gergely, Barna, Hunyadi, Andras, Vermeulen, Jaap J., Grego, Jozef, Sutcharit, Chirasak, Reischuetz, Alexander, Dumrongrojwattana, Pongrat, Botta-Dukat, Zoltan, Oerstan, Aydin, Fekete, Judit & Jochum, Adrienne, 2023, Five times over: 42 new Angustopila species highlight Southeast Asia's rich biodiversity (Gastropoda, Stylommatophora, Hypselostomatidae), ZooKeys 1147, pp. 1-177 : 1

Angustopila cicatricosa Pall-Gergely & Vermeulen sp. nov.

Fig. 34

Type material.

Holotype: Vietnam • 1 empty shell (H: 0.68 mm, D: 0.68 mm); Haiphong Province, Cat Ba Island, near Nat. Park Headquarters, Trung Trang Cave, steep limestone cliff, woody regrowth at base; 20°47.78'N, 106°59.68'E; 25 Sep. 1998; J.J. Vermeulen & A.J. Whitten leg.; HNHM 103481 (original inventory number: JJV 6270).

Diagnosis.

A small Angustopila species with an ovoid shell, a rather strong, pointed parietal tooth, and very strong, elevated spiral striae.

Description.

Shell small for the genus, as high as wide, transparent, glossy, ovoid, dorsal side nearly domed, body whorl widest from standard apertural view; protoconch consists of 1.5 whorls, with very weak spiral striation preceding the first teleoconch whorl; teleoconch ornamented with irregular, very weak radial growth lines and strong, elevated rows of spiral threads (ca. 14 on body whorl from apertural view); whorls 4, rounded; aperture slightly oblique to shell axis from lateral view; umbilicus wide; aperture reniform; peristome edge slightly thickened and expanded, not reflected; parietal callus separated from penultimate whorl; aperture with a well-developed, deeply situated, pointed (short) parietal tooth.

Measurements (in mm).

H = 0.68, D = 0.68, H/D*100 = 100, RUD = 27.9 (holotype).

Differential diagnosis.

This species is characterised by the small size and the strong spiral striation. Angustopila fraterminor sp. nov. is larger with a higher spire, its shell surface is dull (glossy in A. cicatricosa sp. nov.), the aperture bears a longer parietal tooth (pointed in A. cicatricosa sp. nov.), and its peristome edge is less thickened, rather sharp, and slightly expanded. Angustopila maasseni sp. nov. also has a duller shell surface with weaker spiral striae, and a lower spire. Angustopila psammion has a lower spire, a wider umbilicus, and a smaller parietal tooth.

Etymology.

The specific epithet refers to the scar-like, strong spiral striae.

Distribution.

This species is only known from the type locality, Trung Trang Cave (Fig. 24 ).

Remarks.

At first, we considered this individual shell to belong to A. fraterminor sp. nov., to A. maasseni sp. nov., or to A. psammion . However, in addition to the differences regarding shell shape between A. cicatricosa sp. nov. and those two species, A. cicatricosa has an entirely different appearance (strongly striated, glossy) under the microscope. Given that single-site endemic species are not uncommon in the Halong Bay area, we consider this morphologically distinct shell a separate species.

Figures

Figure 24. Distribution of Angustopila species in the Halong Bay area.

Figure 34. Angustopila cicatricosa Pall-Gergely & Vermeulen, sp. nov. (holotype, HNHM 103481). Apertural (A), lateral (B), apical (C) and ventral (D) sides of the shell; microstructure of the protoconch (E), microstructure on ventral (F) and frontal (G) surface of the body whorl.