Diancta rotunda, Neubert, Eike & Bouchet, Philippe, 2015

Neubert, Eike & Bouchet, Philippe, 2015, The Diplommatinidae of Fiji - a hotspot of Pacific land snail biodiversity (Caenogastropoda, Cyclophoroidea), ZooKeys 487, pp. 1-85 : 18-19

Taxon classification Animalia Mesogastropoda Diplommatinidae

Diancta rotunda sp. n. Figs 38-40

Type material.

Holotype MNHN IM-2000-27429, paratypes MNHN/213 IM-2000-27430, NMBE 516876/20. Type locality: Viti Levu, Saweni karst, 50-60 m, dry forest, -17.9032 177.7983, leg. Bouchet, 22.08.1998.

Material.

ZMZ 526682c/2, Viti Levu, leg. Graeffe 1872.

Etymology.

Latin adjective rotundus, -a, -um = rounded; with reference to the shape of the aperture.

Diagnosis.

Shell sinistral, small, whitish, penultimate whorl enlarged, change in ribbing pattern of teleoconch, columellar plate reduced, a small palatal fold.

Description.

Shell sinistral, elongate oval, small, whitish to translucent; last whorl strongly constricted; protoconch small, smooth; umbilicus slit-like open to completely closed, periomphalum concave; teleoconch sculpture of coarse spacious ribs on the upper whorl, fine and dense on the medium and coarse and spacious on the last whorl; penultimate whorl enlarged; last whorl slightly ascending; aperture circular, peristome funnel-shaped, doubled; aperture slightly detaching from last whorl; no pleats visible in the aperture; inside the shell, columellar plate reduced, with a small palatal fold opposite.

Operculum corneous, flat, internally with a small lamella, OD = 0.4.

Measurements.

Holotype (Fig. 38): H = 2.65; D = 1.68; PH = 1.07; PD = 1.03; W = 5.5.

Distribution

(Fig. 170). Only known from the type locality.

Remarks.

Diancta rotunda sp. n. is one of the smallest species of the genus in Fiji, along with Diancta distorta sp. n., Diancta densecostulata sp. n., Diancta macrostoma , and Diancta trilamellata sp. n., but it can be distinguished from these by its enlarged penultimate whorl. Its teleoconch sculpture is similar to that in Diancta trilamellata sp. n., but the latter species possesses a palatalis and parietalis.