Angustopila rara 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 rara Pall-Gergely & Hunyadi sp. nov.

Fig. 92

Type material.

Holotype: Vietnam • 1 empty shell (H: 0.8 mm; D: 0.72 mm); Thanh Hóa Province, 3.6 km northwest from centre of Ngọc Lặc on road no. 15, 600 m north from Làng Săt, rock wall (locality code: 2020/35); 20°05.90'N, 105°21.58'E; 55 m a.s.l.; 12 Feb. 2020; A. Hunyadi leg.; HNHM 105319.

Diagnosis.

A small, conical Angustopila species with a narrow umbilicus, few (13) spiral striae on the body whorl, and strong apertural barriers (elevated parietal, rather pointed palatal, rather blunt columellar).

Description.

Shell small for the genus, higher than wide; off-white, conical with slowly increasing whorls; body whorl widest from standard apertural view; protoconch consists of nearly 1.5 whorls, with slight indication of spiral striation at the end; teleoconch with some fine, weak, irregular radial growth lines and much stronger, elevated, widely-spaced spiral striae (ca. 10 or 11 on body whorl from standard apertural view); whorls 4, rounded; aperture only slightly oblique to shell axis from lateral view; umbilicus moderately wide; aperture broadly heart shaped (although the palatal region of the holotype is slightly broken) with straight parietal side; peristome expanded, not reflected; parietal callus not detached from penultimate whorl; parietal tooth elevated, straight, tongue-like with narrower (slender) base and thickened (widened) end (i.e., the cross sectional view of the parietal lamella is club-shaped); palatal tooth situated in the middle of the palatal side, small, denticle-like, situated close to basal lip; columellar tooth situated on the lower portion of the columellar area, as high as palatal tooth but more elongated, and thus, seemingly more blunt.

Measurements (in mm).

H = 0.8; D = 0.72, H/D*100 = 111.1, RUD = 29.6 (holotype).

Differential diagnosis.

Angustopila rara sp. nov. is most similar to A. tridentata sp. nov. in the formation of the apertural barriers. However, it is much smaller, has a conical rather than a concave-conical shell shape, a much narrower umbilicus (this trait is not independent from the previous one) and fewer spiral striae on the body whorl. The columellar tooth of A. rara sp. nov. is situated lower (i.e., closer to the basal region) than that in A. tridentata sp. nov., which resembles a low wart at the middle of the columellar peristome. Among the species possessing two well-developed teeth (parietal + palatal), A. antidomedon sp. nov., A. reticulata sp. nov., and A. tweediei sp. nov. may have an additional, very weak (sub)columellar tooth. Those species differ from A. rara sp. nov. in several other conchological characters. See also under A. apokritodon sp. nov.

Etymology.

The specific epithet Angustopila rara (rare in Latin) refers to the rarity of this species, as only a single shell is known.

Distribution.

This species is known from the type locality only (Fig. 27 ).

Figures

Figure 27. Distribution of Angustopila species.

Figure 92. Angustopila rara Pall-Gergely & Hunyadi, sp. nov. (holotype, HNHM 105319). Apertural (A), ventral (B), apical (C) and lateral (D) sides of the shell; aperture (E); sculpture on the protoconch (F), ventral (G) and frontal (H) surface of the body whorl.