Angustopila tetradon Pall-Gergely & Hunyadi sp. nov.

Figs 93, 94

Type material.

Holotype: Vietnam • 1 empty shell (H: 0.82 mm, D: 0.79); Thanh Hóa Province, Như Thanh District, Hải Vân, Hang Lò Cao Kháng Chiến, vicinity of the cave (locality code: 2020/41); 19°37.08'N, 105°34.63'E; 20 m a.s.l.; 14 Feb. 2020; A. Hunyadi leg.; HNHM 105320.

Paratypes: Vietnam • 76 shells; same data as for holotype; coll. HA • 3 shells; same data as for holotype; coll. JJV • 48 shells; Thanh Hóa Province, Như Thanh District, 600 m south from Xuân Khang along road no. 45, around the cave temple (locality code: 2020/40); 19°40.35'N, 105°31.07'E; 80 m a.s.l.; 14 Feb. 2020; A. Hunyadi leg.; coll. HA.

Additional material.

Vietnam • 22 j/b shells; same data as for holotype; coll. HA • 1 j/b shell; Thanh Hóa Province, Như Thanh District, 600 m south from Xuân Khang along road no. 45, around the cave temple, (locality code: 2020/40); 19°40.35'N, 105°31.07'E; 80 m a.s.l.; 14 Feb. 2020; A. Hunyadi leg.; coll. HA.

Diagnosis.

A small, conical Angustopila species with a strong parietal tooth, a strong subcolumellar tooth, and two strong palatal teeth situated relatively close to peristome edge.

Description.

Shell small for the genus, slightly higher than wide or slightly wider than high; colourless, translucent, conical-globular with a high-domed spire; body whorl widest from standard apertural view; protoconch consists of ca. 1.5 whorls, with weak signs of spiral striation preceding the first teleoconch whorl; teleoconch with some fine, irregular radial growth lines and much stronger, equidistantly-arranged spiral striae (ca. 15-17 on body whorl from standard apertural view); whorls 3.75-4, slightly shouldered; aperture slightly curved and in line with shell axis in lateral view; umbilicus wide; aperture subquadrate, sinulus broad; peristome expanded, not reflected; parietal callus not protruding, not detached from penultimate whorl; parietal tooth prominent, high, perpendicular to parietal side or slightly bent, almost reaching edge of peristome; palatal wall with two rather low but prominent palatal teeth (upper and lower palatal teeth), situated in rather small distance from peristome; subcolumellar tooth low, blunt, nearly reaching peristome edge.

Measurements (in mm).

H = 0.73-0.87, D = 0.74-0.84, H/D*100 = 92.8-113 (n = 14), RUD = 26.3-30.8 (n = 4).

Differential diagnosis.

The upper palatal tooth of A. quadridens sp. nov. is situated deeper, its subcolumellar tooth is more elevated, and its sinulus is narrower resulting in a more elongated aperture shape. Moreover, the shells of A. tetradon sp. nov. are more conical (instead of conical-globular) than those of A. quadridens sp. nov.

Etymology.

The specific epithet refers to the four apertural barriers of this new species ( Angustopila tetradon: τετρα = four, and ὀδούς = tooth).

Distribution.

This species is known from two geographically adjacent sites in Thanh Hóa Province, northern Vietnam (Fig. 55).