Angustopila pusilla Pall-Gergely & Hunyadi, 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 pusilla Pall-Gergely & Hunyadi sp. nov.

Fig. 54

Type material.

Holotype: Laos • 1 empty shell (H: 0.77 mm, D: 0.7 mm); Vientiane Province, 4.5 km west from centre of Vang Vieng, Phone Ngeun, Tham Khan Kham (locality code: 2019/133); 18°55.53'N, 102°24.95'E; 280 m a.s.l.; 14 Oct. 2019; A. Hunyadi leg.; HNHM 105291.

Paratypes: Laos • 5 shells; same data as for holotype; coll. HA • 3 shells; Vientiane Province, 7.5 km west from centre of Vang Vieng, Ban Naka, Tham Poukham (locality code: 2019/131); 18°55.61'N 102°23.77'E; 240 m a.s.l.; 14 Oct. 2019; A. Hunyadi leg.; coll. HA.

Additional material.

Laos • 3 j/b shells; same data as for holotype; coll. HA.

Diagnosis.

A small Angustopila species with an ovoid shell, oblique scratches between spiral striae; a suboval aperture with sharp edge and a deeply set parietal tooth.

Description.

Shell small for the genus, slightly higher than wide; off-white, ovoid, apex nearly domed, body whorl widest from standard apertural view; protoconch consists of 1.25 whorls, with very weak spiral striation; teleoconch finely ornamented with irregular radial growth lines crossed by much stronger rows of equidistantly-spaced microscopic spiral threads; on frontal and ventral surfaces of body whorl spiral and radial lines dominant (ca. 10-12 on body whorl from apertural view); spiral striae with oblique scratches between rows; whorls 4.5, slightly shouldered; aperture slightly oblique to shell axis from lateral view; umbilicus moderately wide; aperture ovoid, peristome very slightly expanded, not reflected, sharp; parietal callus detached from penultimate whorl; aperture with a tiny parietal tooth situated close to parietal callus, but not reaching it.

Measurements (in mm).

H = 0.74-0.77, D = 0.64-0.7, H/D*100 = 110-115.6 (n = 4), RUD = 26.5-27.9 (n = 2).

Differential diagnosis.

Angustopila pusilla sp. nov. is most similar to A. fraterminor sp. nov. in terms of shell size, shape, aperture shape, the oblique scratches between spiral striae and the presence of a single parietal tooth. However, the tooth is situated deep in A. fraterminor sp. nov. and near the peristome edge in A. pusilla sp. nov. Moreover, the spiral striation is much more prominent (elevated) in A. pusilla sp. nov.

Distribution.

This species is known from two nearby localities in Vientiane Province, northern Laos (Fig. 55 ).

Remarks.

The oblique scratches between the spiral striae of the teleoconch are known in only two species, A. pusilla sp. nov. and A. fraterminor sp. nov. This may, despite the large geographic distance, indicate their close relatedness.

Figures

Figure 54. Angustopila pusilla Pall-Gergely & Hunyadi, sp. nov. Holotype (HNHM 105291) (A, C-I) and paratype (B). Apertural (A, B), lateral (C), apical (D) and ventral (E) sides of the shell; microstructure of the protoconch (F), fine sculpture of the frontal part of the body whorl (G), ventral (H) and frontal (I) surface of the body whorl.

Figure 55. Distribution of Angustopila species.