Acmella kanchanaditensis 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 kanchanaditensis Seedee, Dumrongrojwattana & Poeaim sp. nov.

Fig. 7

Type material.

Holotype: Thailand • Wat Pa Kanchanadit , Kadae Subdistrict, Kanchanadit District, Surat Thani Province; 9.1426, 99.4708; November 2023; Kunya Seedee; deposited in the Malacological Collection; catalog no. ZRCBUU 0993 ; GenBank accession number: PV 157995 , SH = 1.41 mm, SW = 1.10 mm, AH = 0.58 mm, AW = 0.51 mm (Fig. 7 A-E , Table 2 ) . Paratype: Thailand • 4 shells; same locality data as holotype; November 2023; deposited in the same institution as the holotype; catalog no. ZRCBUU 0994 ; GenBank accession number: PV 157996 , SH = 1.39–1.52 mm (1.47 ± 0.08 mm), SW = 1.07–1.10 mm (1.08 ± 0.01 mm), AH = 0.51–0.60 mm (0.57 ± 0.04 mm), AW = 0.48–0.50 mm (0.49 ± 0.01 mm) .

Diagnosis.

Shell conical, white; a visible suture; 4 ¾ – 5 whorls. Aperture oblique and oval. The last whorl sculpture has a relief spiral pattern, thin lines and is barely visible. Umbilicus open and narrow.

Description.

Shell conical, white, translucent; apex rounded; whorls convex up to deep suture; 4 ¾ – 5 whorls. Aperture oblique oval, with a wall adjacent to the upper body, a concave part following the shell shape, and a thin peristome. Umbilicus open, narrow, and superficial (Fig. 7 A ). Protoconch sculpture rough and spread across the area (Fig. 7 B, C ). Last whorl sculpture consists of 48 spiral rows with a shallow groove between them. Radial sculpture thin and barely visible (Fig. 7 D ). Operculum paucispiral, thin, transparent, composed of chitin (Fig. 7 E ).

Differential diagnosis.

Acmella kanchanaditensis sp. nov. can be distinguished from A. caelata Vermeulen & Junau, 2007 by its almost invisible radial sculpture. In contrast, in A. caelata , the radial sculpture remains faintly visible in certain areas. Additionally, A. kanchanaditensis sp. nov. has a higher number of whorls. This new species also closely resembles A. changphueakensis sp. nov. in having spiral sculpture, but the spiral rows in A. kanchanaditensis sp. nov. are thinner and more widely spaced. In contrast, A. krueangensis sp. nov. and A. thamsingensis sp. nov. exhibit well-developed radial sculpture, which is lacking in the present species.

Etymology.

The specific name kanchanaditensis is derived from Wat Pa Kanchanadit, where this species was discovered.

Habitat and distribution.

This species is known only from the study site.

Ecology.

The new species is found in caves where no light penetrates, specifically in areas where water seeps through stalactites and stalagmites.

Figures

Figure 7. Scanning electron micrographs (SEM) of Acmella kanchanaditensis 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).