Acmella krueangensis Seedee, Dumrongrojwattana & Poeaim, 2025

Seedee, Kunya, Dumrongrojwattana, Pongrat & Poeaim, Supattra, 2025, Four new species of genus Acmella W. T. Blanford, 1869 (Gastropoda, Assimineidae) from Southern Thailand, ZooKeys 1256, pp. 275-292 : 275-292

Acmella krueangensis Seedee, Dumrongrojwattana & Poeaim sp. nov.

Fig. 4

Type material.

Holotype: Thailand • Phra Krueang Cave , Bang Bon Subdistrict, Kra Buri District, Ranong Province; 10.3265, 98.7646; November 2023; Kunya Seedee; deposited in the Malacological Collection; catalog no. ZRCBUU 0987 ; GenBank accession number: PV 157989 , SH = 1.51 mm, SW = 1.09 mm, AH = 0.58 mm, AW = 0.53 mm (Fig. 4 A – E , Table 2 ) . Paratype: Thailand • 6 shells; same locality data as holotype; November 2023; deposited in the same institution as the holotype; catalog no. ZRCBUU 0988 ; GenBank accession number: PV 157990 , SH = 0.97–1.55 mm (1.37 ± 0.23 mm), SW = 0.68–1.14 mm (1.01 ± 0.18 mm), AH = 0.39–0.58 mm (0.57 ± 0.07 mm), AW = 0.45–0.56 mm (0.52 ± 0.08 mm) .

Diagnosis.

Shell conical, white, translucent; 4 ½ – 5 convex whorls with a deep suture. Aperture obliquely oval. The last whorl sculpture is characterized by a distinct reticulated (mesh-like) pattern. Umbilicus narrow and open.

Description.

Shell conical, white, and translucent, with a rounded apex. Whorls convex, with a deep suture, totaling 4 ½ – 5 whorls. The aperture is obliquely oval, with a thin peristome and a concavity adjoining the upper body. Umbilicus open, narrow, and shallow (Fig. 4 A ). Protoconch with scattered malleated sculptures extending to the second whorl (Fig. 4 B, C ). The last whorl has a well-defined reticulated sculpture, formed by conspicuous radial and spiral elements, with unevenly tapered spiral lines (Fig. 4 D ). Operculum is thin, transparent, paucispiral, and chitinous (Fig. 4 E ).

Differential diagnosis.

Acmella krueangensis sp. nov. closely resembles A. cyrtoglyphe in general shell sculpture, particularly the presence of both radial and spiral elements. However, A. krueangensis sp. nov. differs by exhibiting more pronounced and evenly spaced radial ribs and a clearer reticulate (net-like) pattern formed by the intersection of radial and spiral elements. In contrast, the other three species possess sculpture dominated by spiral elements with less prominent or absent radial components, resulting in a predominantly spiral pattern rather than a net-like appearance.

Etymology.

The specific epithet krueangensis refers to Phra Krueang Cave, the type locality where the new species was discovered.

Habitat and distribution.

Currently known only from the type locality, Phra Krueang Cave, Ranong Province, Thailand.

Ecology.

This species inhabits dark, moist cave environments characterized by stalactites and stalagmites without evidence of surface water seepage.

Figures

Figure 4. Scanning electron micrographs (SEM) of Acmella krueangensis sp. nov. (A – E) various shell views. A. Overall shell view; B, C. Protoconch and sculpture details; D. Last whorl sculpture; E. Operculum. Scale bars: 0.5 mm (A, B); 0.1 mm (C – E).