Cycloryx rohiniae Páll-Gergely & Aravind sp. nov.

urn:lsid:zoobank.org:act: 80122B22-6AEE-4698-8E7A-62068B3CAE76

Fig. 27A–E

Diagnosis

A large species of Cycloryx with smooth R3.

Etymology

The new species is named after Ms Rohini Nilekani, author, environmentalist and acclaimed philanthropist.

Type material examined

Holotype

INDIA – Mizoram • empty shell (D: 3.7 mm, H: 4.1 mm, Fig. 27A–E); Blue Mountain, Lawngtlai district; 22.727° N, 93.135° E; 1400 m a.s.l.; 27 Jan. 2019; N.A. Aravind leg.; Ar37; NZSI LM1717.

Paratype

INDIA – Mizoram • 1 empty shell; same data as for holotype; Ar34; NZSI LM1718 • 1 empty shell; same data as for holotype; Ar35; NZSI LM1719 .

Description

Shell large for the genus, all available shells slightly corroded, original colour may be greenish-yellowish, semitranslucent; shell conical or conical-globular, height and width approximately equivalent; body whorl rounded; protoconch smooth, glossy, consisting of 1.5 or slightly fewer whorls; R1 of ca 2–2.25 whorls, regularly ribbed, rib density gradually decreases towards end of R2 (last half whorl with ca 16 ribs); ribs thread-like, low; fine, dense spiral striation discernible between ribs; boundary between R1 and R2 not conspicuous, but clearly visible due to increase in rib density (R2 ribs twice as dense as ribs at the end of R1); R2 practically smooth, its “ribs” (6–7 in number) are not elevated from the surface, represented as slender, light stripes; sutural tube short, cylindrical; R2+R3 ca quarter whorl, R3 ca 3 times as long as R2; boundary between R2 and R3 clearly visible due to a shallow constriction; R3 with a low central, long swelling, smooth, only fine growth lines visible but no ribs; aperture slightly oblique to shell axis, rounded; inner and outer peristomes clearly separated; inner peristome slightly protruding and expanded; outer peristome strongly expanded, sharp, and reflected in direction of umbilicus; umbilicus open, narrow, the reflected outer peristome curves into umbilicus, terminating at its centre.

OPERCULUM. A single operculum of the Ar35 shells was examined. The inner side is smooth, without central swelling, outer side multispiral, without elevated lamina.

MEASUREMENTS. D: 3.7 mm, H: 3.5–4.1 mm.

Distribution

Known only from the Blue Mountain region.

Differential diagnosis

The only species with similar size and lack of R3 ribs is C. otiphorus, which has a more pointed (more triangular) shell, and has denser ribs on the apical part. Cycloryx dihingensis, which is similar in shell shape, has strong R3 ribs. All these species inhabit Assam, which geographically is distant from Mizoram.