Diplommatina oviformis Fulton, 1901

Figs 5C, 9I

Diplommatina oviformis Fulton, 1901: 203 .

Diplommatina (Diplommatina) oviformis – Kobelt 1902: 440. — Gude 1921: 326. — Zilch 1953: 21, fig. 125. — Kuznetsov & Schileyko 1997: 140. — Ramakrishna et al. 2010: 90. — Budha et al. 2015: 7.

Diagnosis

Measurements (n = 8): SH 2.1–2.2 mm, SW 1.1–1.2 mm, Wh 6.0. Dextral, penultimate whorl wider than the body whorl. Constriction far behind the aperture (Fig. 9I). Two parietalis: Prt1 long and strong; Prt2 short (Fig. 5C 3). One horizontal palatalis distinct, runs behind the aperture just above the suture from the constriction. Two vertical palatalis: Vpt1 prominent; Vpt2 thin, running parallel to Vpt1, but only over half its length (Fig. 9I). Columellaris well developed, occupying nearly half of the internal surface of the whorl. Columellar tooth strong (Fig. 5C 3). Protoconch smooth, Wh 1.5, with minute evenly distributed pits (Fig. 5C 1). Teleoconch with dense regular radial ribs; about 12–14 ribs/ 0.5 mm on the penultimate whorl; 9–12 ribs/ 0.5 mm on the body whorl towards the aperture (Fig. 5C 2, C 4). Spiral striation present. Umbilicus open. Aperture nearly quadruple. Peristome with two lips, slightly curved at the angular edge; parietal wall raised; inner lip thickened (Fig. 5C 4). Both lips slightly reflected.

Material examined

Possible syntype

INDIA: 1 shell, [ D. oviformis Fulton, 1901, Darjeeling, Sow. & Ful. 01.10.1901] (RBINS 525545, MT1088).

Other material examined

NEPAL:4shells,Okhareni, Shivapuri-Nagarjun National Park, 2267–2326 m, 27.808762 N, 85.421615E, 22 Jun. 2007, R. Devkota and N. Kohar leg. (CDZMTU 042); 6 shells, Deurali, Langtang National Park, 2400–2412 m, 27.805037 N, 85.387862 E, 25 Apr. 2008, P.B. Budha leg. (CDZMTU 043); 16 shells, Phulchowki Hill, Lalitpur District, 2308 m, 27.574557 N, 85.400842 E, 4 May 2007, P.B. Budha leg. (CDZMTU 044); 2 shells, Raniban, Balaju, Kathmandu, 1780 m, 24 Jan. 2009, Srijana Khanal leg. (CDZMTU 059).

Remarks

D. oviformis is a highly variable and very distinct species by its constriction far behind the aperture. This variability is illustrated by the following examples: the syntype shell from Darjiling in the NHM figured by Gude (1921: 326, fig. 36) has a nearly rounded parietal lip, whereas the shell figured by Zilch (1953: fig. 125, cotype SMF 105340, Darjiling, Himalaya) shows a slightly tilted parietal lip towards the columellar axis. Moreover, the apical whorls of the Nepalese shells reported here are comparatively wider than in the shells at NHM and RBINS (525545 from Darjeeling). The two lips of the peristome in the paratype at RBINS are closer to each other than in Nepalese shells. Nevertheless, for the time being we refer to the Nepalese shells as D. oviformis because of the typical constriction far behind the aperture.