Diplommatina Benson, 1849

Walther, Frank & Hausdorf, Bernhard, 2020, Diplommatina boessnecki n. sp. from Nepal (Gastropoda: Diplommatinidae), Zootaxa 4728 (3), pp. 398-400 : 398-400

Diplommatina Benson, 1849

Diplommatina Benson, 1849: 193 . Type species (subsequently designated by Nevill, 1878): Bulimus folliculus Pfeiffer, 1846 .

Diplommatina boessnecki n. sp.

Fig. 1

Type material. Holotype ( Fig. 1 ), ZMH 140165, shell diameter 0.95 mm, shell height 1.74 mm, Nepal, Lalitpur district , W slope of Mount Phulchowki ca. 2.5 km SE of Godawari, 2350 m a.s.l., 27.578°N 85.397°E . Paratypes: CDZMTU022/1; FW 14150/3; SMF 357931 /1 ; ZMH 140166 /1, Nepal, Lalitpur district , W slope of Mount Phulchowki ca. 2.5 km SE of Godawari, 2350 m a.s.l., 27.578°N 85.397°E .

Etymology. We name the species in remembrance of our late friend and colleague Dr. Ulrich Bössneck (1960–2019) who made significant contributions to the knowledge of the molluscan fauna of Nepal.

Diagnosis. Diplommatina boessnecki n. sp. is characterized by its minute-sized, cylindrical-spindle-shaped, densely ribbed shell, with fine spiral striae between the ribs, the rounded last whorl, the ventrolaterally left position of the short, oblique palatal fold and the open umbilicus.

Shell ( Fig. 1 ). Dextral; cylindrical-spindle-shaped with conical early whorls and a narrowed last whorl; with 5.25–5.5 whorls separated by a deep suture; protoconch smooth; teleoconch with slightly oblique ribs, 12–17 (mean 14.2) per 0.5 mm on the penultimate whorl; fewer on the last whorl; with fine spiral striae between the ribs; whitish; subtranslucent; last whorl rounded, with an indistinct ventral constriction; aperture rounded square; upper insertion of the peristome ascending onto the penultimate whorl; insertions of the peristome connected by an indistinct callus; peristome expanded, thickened, doubled; aperture with a weak, deeply situated columellar lamella; with a short oblique spiral palatal fold in the middle of the whorl ventrolaterally left inside the last whorl, and with a short radial palatal fold ventrally close to the suture; umbilicus open.

Measurements (n = 6): shell diameter D: 0.94–0.98 mm, mean 0.96± 0.02 mm; shell diameter at third whorl: 0.79– 0.80 mm, mean 0.79± 0.01 mm; shell height H: 1.70–1.87 mm, mean 1.77± 0.06 mm; aperture diameter: 0.61–0.66 mm, mean 0.63± 0.02 mm; aperture height: 0.59–0.63 mm, mean 0.61± 0.01 mm; D/H: 0.513 –0.576, mean 0.541±0.021.

Remarks. With regard to the almost cylindrical shell shape Diplommatina boessnecki n. sp. is most similar to D. miriensis Godwin-Austen, 1917 from the Miri Hills in Arunachal Pradesh and D. minima Beddome, 1875 from Visakhapatnam in Andhra Pradesh. It differs from both species in the open umbilicus and the larger shell size. Furthermore, it differs from D. miriensis in the uncurved palatal margin of the peristome.

Distribution. Diplommatina boessnecki n. sp. is known only from the type locality.

Figures

FIGURES 1–3. Diplommatina spp. 1. Diplommatina boessnecki n. sp., Nepal, W slope of Mount Phulchowki (holotype ZMH 140165). 2. Diplommatina cf. regularis Fulton, 1901, Nepal, W slope of Mount Phulchowki (ZMH 140167). 3. Diplommatina sp., India, Darjeeling (alleged syntype of D. regularis Fulton, 1901; SMF 105343).