Diplommatina regularis Fulton, 1901

Figs 7A, 9J

Diplommatina regularis Fulton, 1901: 245 .

Diplommatina regularis – Kobelt 1902: 442. — Gude 1921: 330.

Diplommatina (Diplommatina) regularis – Zilch 1953: 21, figs 125–126. — Ramakrishna et al. 2010: 91. — Budha et al. 2015: 7.

Diagnosis

Measurements (n = 8): SH 2.5–3.0 mm, SW 1.3–1.5 mm, Wh 7.0–7.5. Dextral, penultimate whorl slightly larger than the body whorl. Constriction at columellar margin slightly towards the inner lip of the parietal wall (Fig. 9J). One parietalis, short (Fig. 7A 3). One vertical palatalis, parallel to the constriction. One short horizontal palatalis, situated just above the columella (Fig. 9J). Columellaris moderately thin. Columellar tooth weak, only visible in mature shells (Fig. 7A 3). Protoconch smooth, with small pits distributed all over (Fig. 7A 1). Teleoconch with regular radial ribs; about 8–11 ribs/ 0.5 mm on the penultimate whorl; 5–8 ribs/ 0.5 mm on the body whorl towards the aperture (Fig. 7A 2, A 4). Very fine spiral striation present. Umbilicus closed. Outer lip at BeP abruptly curved on the columella, closing the umbilicus. Peristome thin, with two close lips (Fig. 7A 4); AeP slightly curved, a single lip in most immature shells. Very thin parietal callus, extending at the base. Operculum paucispiral, corneous, thin, transparent, slightly concave, outer surface smooth, inner surface with raised peripheral circular edge.

Material examined

Possible syntype

INDIA: 1 shell [ D. regularis Fulton, 1901 Darjeeling Sow. & F. 01.10.1901 1/6] (RBINS 525556, MT1099).

Other material examined

NEPAL: 20 shells, Baghdwar, Shivapuri-Nagarjun National Park, 2314 m, 27.805203 N, 85.390029 E, 24 Jun. 2007, P.B. Budha leg. (CDZMTU 045); 9 shells, Ghopte, Langtang National Park, 3419 m, 28.0193 N, 85.4619 E, 8 Jun. 2007, P.B. Budha leg. (CDZMTU 060); 16 shells, Deurali, Langtang National Park, 3247–3277 m, 28.1059N, 85.3266 E, 6 Jun. 2007, P.B. Budha leg. (CDZMTU 061).

Remarks

D. regularis is a very distinct species due to its regularly increasing whorls. Many shells with adult size show a single, very thin peristomal lip typical of juvenile shells. Juvenile shells show a more distinct constriction at the columellar margin than the fully grown shells.