Chamalycaeus reflectus Páll-Gergely & Aravind, 2025

Chamalycaeus reflectus Páll-Gergely & Aravind sp. nov.

urn:lsid:zoobank.org:act:

Figs 9–10, 12A

Diagnosis

A small species of Chamalycaeus with a ca quarter whorl-long R2+R3, an R3 with a low central swelling (situated slightly closer to the peristome), a strongly expanded outer peristome, and a rounded inner peristome.

Etymology

The specific epithet refers to the reflected outer peristome, which is characteristic of this species.

Type material examined

Holotype

INDIA – Mizoram • 1 empty shell (D: 1.9 mm, H: 1.4 mm, Figs 9, 12A); Blue Mountain, Lawngtlai district ; 22.727° N, 93.135° E; 1400 m a.s.l.; 27 Jan. 2019; N.A. Aravind leg.; Ar 55; NZSI LM1723 View Materials . GoogleMaps

Paratype

INDIA – Mizoram • 1 empty shell; same data as for holotype; NZSI LM1724 View Materials GoogleMaps .

Additional material examined

INDIA – Mizoram • 2 empty shells; same data as for holotype; Ar56; NZSI LM1725 View Materials GoogleMaps • 1 empty shell ( Fig. 10); same data as for holotype; AR44; NZSI LM1913 View Materials GoogleMaps . – Tripura • 1 empty shell ( Fig. 11); South Tripura, Purba Patichhari, Towards Garji from Santirbazar ; 23°24.227′ N, 91°30.294′ E; 31 Jan. 2021; Nipu Kumar Das leg.; NZSI LM 1906 View Materials GoogleMaps .

Description

Shell small, white, fresh shell possibly translucent; shell outline rather rounded in dorsal view; spire slightly elevated, low conical; body whorl rounded; protoconch low, finely granular, spiral striae lacking, consisting of ca 1.5 whorls; R1 of slightly under 1.5 whorls, with strong, sharp, but relatively low radial ribs that become more widely-spaced towards R2; last half whorl of R1 with ca 18 ribs, space between last two R1 ribs twice as large as distance between two ribs half whorl behind the end of R2; spiral striation absent; boundary between R1 and R2 conspicuous due to the sudden increase in rib density; R2 with ca 16 straight, sharp but low ribs; R2+R3 ca quarter whorl or slightly more; R3 and R2 of comparable length, boundary between R2 and R3 clearly visible due to a slight constriction; R3 with moderately long swelling that is situated closer to R3; R3 nearly smooth, with ca 3 weak ribs between swelling and outer peristome; aperture oblique to shell axis, rounded; boundary between inner and outer peristomes conspicuous; inner peristome strongly thickened, protruding and expanded; outer peristome thin, sharp, strongly reflected; umbilicus narrow, ca one fifth of shell width, rounded.

MEASUREMENTS. D: 1.9–2.5 mm, H: 1.4–1.9 mm.

Distribution

Known only from the Blue Mountain region.

Differential diagnosis

We have not found any similar species in the historical collection other than C. sculpturus , with which this species is sympatric. Chamalycaeus sculpturus is similar in shell shape and sculpture, and the ratios of regions. However, its peristome is dominated by the inner peristome, which is fringed and thickened, while the outer peristome is not expanded. In contrast, C. reflectus sp. nov. has a smooth (not fringed) inner, and a strongly expanded outer peristome. Furthermore, the upper apertural incision on C. crispatus is stronger and the R1 ribs (most clearly visible in the area just preceding R2) are denser. The peristome of C. sculptilis ( Fig. 13A–D) is similar to that of C. reflectus , but that species is larger and has a strongly keeled body whorl.

Remarks

The single shell Ar44 ( Fig. 10) is larger than the two type specimens and has a longer R2, while the sculpture and the morphology of the inner and outer peristomes of the type specimens and the Ar 44 specimen is identical. We need more extensive material to understand whether the observed differences represent an intraspecific diversity or differences between species. The two Ar 56 specimens are identical with the Ar 44 specimen but are strongly corroded. The single shell from Tripura ( Fig. 11) is similar to the holotype, but has a less expanded outer peristome, and denser R1 and R2 ribs. Nevertheless, for the time being, we consider it conspecific with C. reflectus sp. nov.