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

Figs 90 , 91

Type material.

Holotype: Vietnam • 1 empty shell (H: 0.93 mm, D: 0.96 mm); Haiphong Province, Halong Bay area, Cat Ba Island, Cave Qua Vang, around cave entrance, rocky limestone slope with low, rather mature forest; 20°48.64'N, 107°04.64'E; 100 m a.s.l.; 6 Jun. 2017; J.J. Vermeulen & K. Anker leg.; HNHM 105318.

Paratypes: Vietnam • 8 shells; same data as for holotype; JJV 16595 • 4 shell; Haiphong Province, Halong Bay area, Cat Ba Island, Cave Qua Vang, inside cave, large, ecologically intact active cave with speleothems; 20°48.64'N, 107°04.64'E; 60 m a.s.l.; 6 Jun. 2017; J.J. Vermeulen & K. Anker leg.; JJV 16592 • 4 shells; Haiphong Province, Halong Bay area, unnamed island off E Coast Cat Ba, south facing bay with beach and densely-vegetated limestone scree slope; 20°45.19'N, 107°04.46'E; 1 Oct. 1998; J.J. Vermeulen & A.J. Whitten leg.; JJV 6216.

Diagnosis.

A small to medium-sized, conical-globular Angustopila species with a strong parietal tooth, a blunt subcolumellar tooth, and two rather blunt, palatal teeth situated far from the peristome edge.

Description.

Shell small- to normal-sized for the genus, slightly higher than wide or slightly wider than high; pale grey, translucent, conical with variable shell height; body whorl widest from standard apertural view; protoconch consists of ca. 1.25-1.5 whorls, with strong spiral structure on the entire protoconch; teleoconch with some (mostly weak but occasionally stronger) irregular radial growth lines and equidistantly-arranged spiral striae (ca. 15-20 on body whorl from standard apertural view); whorls 4-4.25, slightly shouldered; aperture only very slightly oblique to shell axis from lateral view; umbilicus wide; aperture pear-shaped, sinulus relatively wide; peristome expanded, not reflected; parietal callus protruding, detached from penultimate whorl; parietal tooth prominent, high, perpendicular to parietal side, almost reaching edge of peristome; palatal wall with two strong palatal teeth (upper and lower palatal teeth), situated in large distance from peristome; subcolumellar tooth well-developed, blunt, nearly reaching peristome edge.

Measurements (in mm).

H = 0.81-1.05, D = 0.81-0.96, H/D*100 = 94.3-113.5 (n = 8), RUD = 29.7-32.3 (n = 3).

Differential diagnosis.

Angustopila quadridens sp. nov. can be distinguished from all other Angustopila species based on the relatively large, domed shell, and the four apertural teeth. For differences with the most similar A. hyron sp. nov. and A. tetradon sp. nov., see under those species.

Etymology.

The specific epithet refers to the four teeth of this new species.

Distribution.

This species is known from two geographically adjacent sites in the Halong Bay Area: Qua Vang Cave on Cat Ba Island, and ca. 6.4 km south on a small unnamed island (Fig. 24 ).

Remarks.

Shells of sample JJV 6216 are slightly smaller and have a lower spire than those of the type lot at the entrance of the Cave Qua Vang. However, other shells collected inside the cave also bear lower spires. Thus, we consider this trait to be intraspecifically variable.

Figures

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

Figure 90. Angustopila quadridens Pall-Gergely & Vermeulen, sp. nov. (holotype, HNHM 105318). Apertural (A), ventral (B), apical (C) and lateral (D) sides of the shell; sculpture on the protoconch with protoconch-teleoconch boundary (E), aperture (F), ventral (G) and frontal (H) surface of the body whorl.

Figure 91. Angustopila quadridens Pall-Gergely & Vermeulen, sp. nov., JJV 6216. Apertural (A), ventral (B), apical (C) and lateral (D), sides of the shell; aperture (E); sculpture on the protoconch with protoconch-teleoconch boundary (F), ventral (G) and frontal (H) surface of the body whorl.