Angustopila fraterminor 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 fraterminor Pall-Gergely & Vermeulen sp. nov.

Fig. 45

Type material.

Holotype: Vietnam • 1 empty shell (H: 0.77 mm, D: 0.7 mm); Quang Ninh Province, Halong Bay, Cap La Cave, deposit of soil fallen in through roof in pristine cave, vegetation outside cave high and woody; 20°51.79'N, 107°13.54'E; 7 Mar. 2018; J.J. Vermeulen & K. Anker leg.; HNHM 105287.

Paratypes: Vietnam • 368 shells; same data as for holotype; JJV 17635 • 10 shells; same data as for preceding, coll. HA • 1 shell; Quang Ninh Province, Halong Bay area, Dao Bo Hon, Song Sot Cave, drift material washed together over sinkhole in cave; 20°50.83'N, 107°05.67'E; 2 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6247.

Diagnosis.

A small to medium-sized Angustopila species with an ovoid shell, and a strongly developed, but deeply set parietal tooth.

Description.

Shell small to medium-sized for the genus, slightly higher than wide; off-white, ovoid, apex 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 finely ornamented with irregular radial growth lines crossed by fine rows of equidistantly-spaced spiral threads; on frontal and ventral surfaces of body whorl spiral and radial lines dominant (ca. 12 on body whorl from apertural view); spiral striae occasionally with oblique scratches between rows; whorls 4, rounded or slightly shouldered; aperture oblique to shell axis from lateral view; umbilicus moderately narrow; last 1/4 whorl slightly loosely coiled (reflected in the widened umbilicus); aperture ovoid, peristome slightly expanded, not reflected; parietal callus detached from penultimate whorl; aperture with a well-developed, deeply set parietal tooth.

Measurements (in mm).

H = 0.75-0.93, D = 0.7-0.82, H/D*100 = 104.1-113.4 (n = 6), RUD = 25.7-28.6 (n = 3).

Differential diagnosis.

Angustopila fraterminor sp. nov. differs from A. fratermajor sp. nov. by the smaller, more ovoid shell, and the somewhat stronger parietal tooth. These two species also live in sympatry. See also under A. cicatricosa sp. nov. and A. pusilla sp. nov.

Etymology.

The specific epithet refers to A. fratermajor sp. nov., which is a very similar, but larger species from the same geographic area.

Distribution.

This species is only known from the type locality of Cap La Cave, Quang Ninh Province (Fig. 44 ).

Remarks.

The sculpture of A. fraterminor sp. nov. and A. pusilla sp. nov. is very similar, which may indicate that they are close relatives. See also under that species.

Figures

Figure 44. Distribution of Angustopila species. Note that the occurrence of Angustopila fratermajor Pall-Gergely & Vermeulen, sp. nov. in the Pu Puong National Park (Thanh Hoa Province) is not indicated.

Figure 45. Angustopila fraterminor Pall-Gergely & Vermeulen, sp. nov. (holotype, HNHM 105287). Apertural (A), lateral (B), apical (C) and ventral (D) sides of the shell; aperture (E), microstructure of the protoconch (F), ventral (G) and frontal (H) surface of the body whorl.