Entadella concava, Páll-Gergely & Hunyadi, 2019

Páll-Gergely, Barna & Hunyadi, András, 2019, Two new species of Entadella Páll-Gergely & Hunyadi in Páll-Gergely et al., 2016 from Vietnam (Gastropoda: Heterobranchia: Camaenidae), Raffles Bulletin of Zoology 67, pp. 694-700 : 696-698

Entadella concava , new species

( Fig. 3 )

Type material. Holotype (1 shell, D: 30.7 mm, H: 14.7 mm; Fig. 3A ) ( HNHM 104401 ), Vietnam, Tuyên Quang Province, Minh Quang, Làng Linh 2 km towards Th ồ Bình , right side of road no. 188, 105 m a.s.l., 22°20.428′N, 105°10.703′E (locality code: 2012/52), coll. A. Hunyadi, 02 June 2012; 2 paratypes (HA; one figured as Fig. 3B ), same data as holotype.

Non-type material. Figured juvenile shell ( HNHM 104402 ; fig. 3C–D), same data as holotype ; 1 juvenile shell (HA), same data as holotype .

Description of the shell. Shell medium-sized, dextral, relatively thin-walled. Original colour unknown because only weathered shells were available. Dorsal surface flat or only very slightly domed, but from the side/front view, the spire is sunken below the level of the penultimate whorl in all available (5) specimens. Shell outline rounded from dorsal view, whorls grow regularly. Body whorl rounded from ventrolateral direction. Whorls 6, separated by shallow suture, last whorl much wider than penultimate one resulting in a “nautiliform” shape from dorsal view. Protoconch ( Fig. 3C ) consisting of 2.25 whorls. First 1.5 whorls glossy, smooth, latter whorls becoming somewhat wrinkled with some small tubercles near suture. Teleoconch sculpture ( Fig. 3D ) dominated by irregular growth wrinkles and dense, radial riblets near the suture, which are often broken off to single, elongated tubercles. Weak, dense spiral striation appears on the dorsal side after 3.5 whorls and remains equally strong until peristome. Spiral striation of similar density discernible on both ventral and dorsal sides. Umbilicus open but narrow, showing all whorls, its edge slightly covered by reflected peristome. Aperture semilunar, elongated in direction of umbilicus, slightly oblique to the shell axis from lateral view. Peristome slightly thickened and reflected. Parietal callus present only as fine calcium layer on the parietal shell wall, but its surface could not be examined due to corrosion.

Measurements. D = 29.6–30.7 mm, H = 14.6–14.9 mm (n = 3)

Differential diagnosis. Entadella concava , new species, differs from all other Entadella species by the sunken initial whorls and the less dense whorls. The geographically most adjacent E. athrix has a higher spire, thinner peristome, and its last whorl is not conspicuously wider than the penultimate one. The differences from Entadella kilchomani Páll-Gergely , new species, are given under that species.

Etymology. The specific epithet refers to the sunken initial whorls, which results in a concave dorsal surface.

Figures

Fig. 3. Entadella concava, new species. A, holotype (HNHM 104401); B, paratype (coll. HA); C, protoconch of a juvenile shell (not paratype, HNHM 104402); D, teleoconch sculpture of the same shell. Oval area shows elongated tubercles along the suture on the protoconch (C) and on the teleoconch (D), rectangular area shows spiral striation.