Dicharax pallgergelyi Jirapatrasilp & Inkhavilay 2026, sp. nov.

Information from the abstract

Dicharax pallgergelyi Jirapatrasilp & Inkhavilay sp. nov. Figs 5 B, 7 Type material. Holotype. Laos • 1 shell, SH = 1.5 mm, SW = 2.3 mm; Vientiane Province, Feuang District, unnamed limestone hill (loc. MF 1); 18°40'29.2"N, 102°02'18.4"E; 320 m a. s. l.; 7 Oct. 2024; leg. CU - NUOL expedition team; CUMZ 14482 (Fig. 5 B). Paratypes. Laos • 5 shells; same data as for holotype; CUMZ 14482 A (Fig. 7). Diagnosis. Shell depressed-conical. Spire ~ 1 / 5 of shell height. R 1 ~ 1 ¾ whorls with regular, very low ribs. R 2 ~ 1 / 5 whorl and nearly as long as or slightly shorter than R 3; with ~ 25 ribs; ribs becoming thicker at the end of R 2. R 3 ~ 1 / 5 whorl with very fine, close-set ribs. Apertural tube coiling slightly downward from the horizontal axis of the shell, expanding near the end of the aperture. Inner peristome blunt, thick, protruding. Outer peristome thickened, multilayered, expanded, not reflected. Differential diagnosis. Dicharax pallgergelyi sp. nov. is similar to D. notus (Godwin-Austen, 1914) (Páll-Gergely et al. 2025: fig. 71 a – e) in shell shape and size, but the new species possesses a lesser number of R 2 ribs (25–28) with lower rib height, compared to those in D. notus (48–50, more elevated R 2 ribs with T-shaped cross section). In addition, D. pallgergelyi sp. nov. also differs by a distinct protruding inner peristome which is blunt and thick. Description. Shell depressed-conical, solid, translucent, SH 1.4–1.5 mm, SW 2.1–2.4 mm (n = 6). Shell outline oval in apical view, spire ~ 1 / 5 of shell height. Whorls ~ 3 ¾; spiral striation lacking on the entire shell. Protoconch low, ~ 1 ¾ whorls, smooth. Radial ribs regular and very low, indistinct starting from R 1, becoming more distinct toward the end of R 2, and finer, more close-set, and less distinct in R 3. R 1 ~ 1 ¾ whorls with ~ 38 ribs in ¼ whorl adjoining R 2. Boundary between R 1 and R 2 distinct as R 2 contains thicker and more distinct ribs. R 2 ~ 1 / 5 whorl and nearly as long as or slightly shorter than R 3; with ~ 25 ribs; ribs becoming thicker at the end of R 2. Boundary between R 2 and R 3 distinct as a slight constriction. R 3 ~ 1 / 5 whorl with very fine, close-set ribs; apertural tube coiling slightly downward from the horizontal axis of the shell, expanding near the end of the aperture. Aperture round. Peristome double with prominent outer peristome. Inner peristome blunt, thick, protruding. Outer peristome thickened, multilayered (visible in lateral view), expanded, not reflected. Umbilicus elliptical, open, approximately one third of shell width. Operculum unknown. Etymology. The species name is in honour of Dr. Barna Páll-Gergely, a prominent Hungarian malacologist, who extensively studied the taxonomy of the Alycaeinae and first recognised this species as new to science. Distribution. Known only from the type locality in Feuang District, Vientiane Province, Laos. Remarks. The number range of R 2 ribs and the occurrence of the protruding inner peristome are consistent across all specimens of this new species, suggesting that these are important diagnostic characters.

Why this record is monitored

This record has an Impact Signal of 73/100 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 · Marine Biology and Ecology Research · Calcium Carbonate Crystallization and Inhibition