Chamalycaeus dayangmerindu Aulia & Nurinsiyah sp. nov.

Fig. 5 c

Material examined.

Holotype. Indonesia • Shell H = 2.7 mm; D = 3.9 mm; HA = 1.4 mm; DA = 1.4 mm; whorl 3; South Sumatra, Ogan Komering Ulu, Padang Bindu (Plot 11); 4°04.04'S, 103°55.24'E; alt. 124 m; May-June 2021; Nurinsiyah leg.; MZB Gst. 24.132. Paratypes. Indonesia • South Sumatra, Ogan Komering Ulu, Semidang Aji, Suka Merindu (Plot 11); 4°04.11'S, 103°55.34'E; alt. 124 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24131/40 • South Sumatra, Ogan Komering Ulu, Semidang Aji, Suka Merindu (Plot 8); 4°04.06'S, 103°55.40'E; alt. 134 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24132/1.

Description (n = 11).

Shell minute size with H = 2–2.7 mm (mean 2.3 mm); D = 3.1–4.1 mm (mean 3.5 mm); HA = 1–1.4 mm (mean 1.2 mm); DA = 1–1.2 mm (mean 1.1 mm); 3–3.5 whorls. Shell dextral; depressed conical shaped, wider than tall, with depressed apex; white color and glossy; body whorl rounded, separated by a deep suture; protoconch smooth; the teleoconch with fine spiral lines, without radial ribs; constriction ~ 0.5 mm from aperture; followed by short bulging sutural tube, with 7–9 radial micro-tunnels; region termed R 3 by Páll-Gergely et al. (2017) (which usually bears a swelling in most species of Alycaeinae) absent (i. e., the aperture is situated in the immediate vicinity of the constriction); aperture almost perfectly round, without wrinkles; peristome thickened, not reflected; the boundary between inner and outer peristomes visible but not conspicuous; umbilicus wide.

Habitat.

Limestone rocks.

Distribution.

The species is so far only recorded from Padang Bindu Karst, South Sumatra.

Remarks.

Although spiral striation generally absent in Dicharax (Páll-Gergely et al. 2020), this character is obvious in D. candrakirana from Sempu Island, Java (Nurinsiyah and Hausdorf 2017). However, that species has a well-developed R 3 with low swelling. The most similar species are Chamalycaeus microconus Möllendorff, 1887 and Chamalycaeus mixtus Zilch, 1957 from Peninsular Malaysia, due to the absence of R 3. However, the former differs from the new species due to its strong radial ribs, and the latter has practically no constriction and its peristome is not expanded.

Etymology.

The species name Dayang Merindu was inspired by Princess Dayang Merindu, a figure from local folklore. According to the legend, Princess Dayang Merindu ignored the greeting of a man, as she was already married. Her action was then perceived as arrogance, and the man cursed her into stone. The stone associated with this tale is located inside Gua Putri, a karst cave formation in the Padang Bindu area.