Dicharax praeda Páll-Gergely & Aravind, 2025

Dicharax praeda Páll-Gergely & Aravind sp. nov.

urn:lsid:zoobank.org:act:

Figs 12B–C, 57

Diagnosis

A small species of Dicharax with glossy R1 and R3, a combined length of R2+R3 reaching nearly half a whorl, and a strongly inflated R3 bearing a single dent near the suture on the upper part of the R3 swelling.

Etymology

The specific epithet ‘ praeda ’ (Latin for ‘prey’) refers to the dent on R3 resembling a bite trace. To be used as a noun in apposition.

Type material examined

Holotype

INDIA – Mizoram • empty shell (D: 3 mm, H: 2.4 mm, Figs 12B–C, 57); Blue Mountain, Lawngtlai district ; 22.727° N, 93.135° E; 1400 m a.s.l.; 27 Jan. 2019; N.A. Aravind leg.; Ar 67; NZSI LM1740 View Materials . Paratype GoogleMaps

INDIA – Mizoram • 1 empty shell; Blue Mountain, Lawngtlai district ; 22.727° N, 93.135° E; 1400 m a.s.l.; 27 Jan. 2019; N.A. Aravind leg.; Ar 67; NZSI LM1741 View Materials GoogleMaps .

Description

Shell small, yellowish, glossy, semitranslucent; shell outline rather rounded in dorsal view except for the conspicuously inflated R3; spire elevated, conical; body whorl rounded; protoconch low, glossy, consisting of ca 1.5 whorls; R1 of 1.75–2 whorls, glossy, smooth, with some inconspicuous, widely-spaced, incomplete (i.e., present only near the suture) ribs on the last ca 0.75 whorl of R1; spiral striation absent; boundary between R1 and R2 conspicuous due to the sudden change to a regularly ribbed surface; R2 with ca 22–26 straight, sharp, lamella-like ribs; R2 ribs slightly curved towards aperture, the spaces between the ribs are wider than the width of a single rib; R2+R3 nearly half whorl; R3 slightly longer than R2; boundary between R2 and R3 clearly visible due to a deep constriction; entire R3 strongly swollen, forming a blunt tip towards constriction; a shallow, inconspicuous, elongated dent is situated near the upper end of the swelling, nearly touching the suture; aperture strongly oblique to shell axis, rounded with a slight upper (parieto-palatal) incision; boundary between inner and outer peristomes conspicuous; inner peristome slightly thickened and protruding; outer peristome more conspicuous, moderately sharp, strongly expanded, especially on the upper palatal and basal side; umbilicus very narrow, slit-like.

MEASUREMENTS. D: 2.9–3 mm, H: 2.4 mm.

Distribution

Known only from the Blue Mountain region.

Differential diagnosis

The most similar species is Dicharax diagonius , which has complete R1 ribs on the entire region (absent on the first 1.5 whorl, and on the last ca 1 whorl present only near the suture in the new species), more curved R2 ribs, and a more pointed tip of the R3 swelling.

Dicharax chennelli differs from the new species in the following characteristics: the ribs near the suture of R1 are stronger in D. chennelli , and the R2 ribs are more curved towards the aperture, forming an almost continuous flat area, while the R2 ribs of the new species are rather straight, and therefore they do not form a flat surface. The dorsal side of the R3 swelling of D. chennelli bears two dents, one situated on the upper part, and the lower at its middle, both being the same distance from the suture. In contrast, the upper dent nearly touches the suture in the new species, and the lower dent is not visible. Furthermore, the tip of the swelling (i.e., the part situated closest to the constriction) is sharper in D. chennelli , and blunter in the new species. Lastly, D. chennelli has a basal incision, while the aperture of the new species is perfectly rounded.

Dicharax habiangensis has a shorter R2 and R3, the R2 ribs are more curved, the dent on the R3 is situated at some distance from the suture (touching the suture in the new species), and the entire R3 is separated from the penultimate whorl by the deeper suture.

Dicharax subculmen has a lower spire, denser ribbing on R1, and a deeper dent on the R3 swelling. Dicharax nowgongensis has stronger and more complete R1 ribs, but the R3 of the holotype of that species was broken.