Diplommatina prolixa Tongkerd 2026, sp. nov.

Information from the abstract

6Diplommatina prolixaTongkerd sp. nov. Figs 11 B, 12 A Type material. Myanmar • Holotype. CUMZ 15458 (height 2.2 mm, width 1.2 mm; Figs 11 B, 12 A) from Rathye Pyan Cave, Hpa An City, Kayin State; 16°50'6.2"N, 97°34'14.5"E, 15 m a. s. l.; P. Tongkerd and S. Panha leg. • Paratype. CUMZ 25459 (1 damaged shell); same data as for holotype. Diagnosis. Shell small, dextral, elongate-pyramidal, fusiform, ~ 6 ¼ convex whorls. Penultimate whorl widest. Shell with broadly spaced radial ribs, fine spiral striations throughout. Peristome double, expanded. Aperture rounded with three barriers: parietalis, palatalis and columellaris. Description. Shell dextral, elongate-pyramidal fusiform, whisper white or transparent yellow, apex orange. Shell height 2.0 and 2.2 mm; shell width 1.1 and 1.2 mm. Whorls 6 ¼, and broadly convex; spire elongate conical; suture wide and deep. Protoconch ~ 1 ½ whorls, with round malleated pits. Teleoconch with wide, regularly spaced radial ribs; ribs slightly sinuous, prominent near suture. Ribs with 3–4 ribs / 0.5 mm on penultimate whorl, 4–5 ribs / 0.5 mm on last whorl towards aperture. Spiral striations very weak, fine on only earlier whorls. Last whorl narrower than penultimate whorl. Constriction externally weakly conspicuous; internal constriction marked with distinct vertical ridge. Aperture circular with three barriers: parietalis very strong, prominent ridge; palatalis moderately long, strong, horizontal ridge; columellaris distinctly prominent, tall ridge, continuous with peristome, and slightly deflected downward toward palatal wall (Fig. 11 B). Peristome broadly expanded, double; outer peristome broader than inner peristome. Lip thickened, multi-layered; parietal callus thick, expanded. Columella straight. Umbilicus closed. Differential diagnosis. Diplommatina prolixa sp. nov. is most similar in shell sculpture to D. oligopleuris Blanford, 1868 from India and D. sperata Blanford, 1862 from Rakhine State, Myanmar. However, it differs from D. oligopleuris in having an elongate fusiform shell, whereas D. oligopleuris has an ovate-fusiform shell. In addition, the new species can be distinguished from D. sperata by its more widely spaced radial ribs and a peristome edge that lacks protrusion, while D. sperata has more narrowly spaced radial ribs and a peristome with a protruding columellar edge. For further comparison, D. prolixa sp. nov. can be distinguished from D. naiyanetri Panha, 1998 from southern Thailand by its wider spacing between the radial ribs, a rounded aperture, and without a pointed columellar edge. In contrast, D. naiyanetri possesses more narrowly spaced radial ribs, somewhat squarish aperture, and a clearly defined columellar notch. In addition, D. naiyanetri (Fig. 12 B) was recorded from a locality approximately 1,040 km south of the type locality of this new species. Distribution. Diplommatina prolixa sp. nov. is currently known only from its type locality in Kayin State, Myanmar. This new species inhabits limestone cliff faces and rock crevices, with surrounding vegetation (Fig. 1 A). Etymology. The specific name prolixus is a Latin word meaning wide or broad and alludes to broadly spaced radial ribs, which characterises this species. Remarks. The shell of D. prolixa sp. nov. is comparable to that of D. exilis from Mandalay Region, Myanmar (Kobelt 1902). However, the radial ribs of D. exilis are narrower than those of D. prolixa sp. nov.

Why this record is monitored

This record has an Impact Signal of 75/100 based on recency, source, collaboration, and bibliographic signals. It prioritizes monitoring and is not a judgment of research quality.

Related topics: Diatoms and Algae Research · Subterranean biodiversity and taxonomy · Mollusks and Parasites Studies