Pincerna crenilabris crenilabris (Möllendorff, 1897)

Figs 6, 9 c

Alycaeus (Orthalycaeus) crenilabris Möllendorff, 1897: 93.

Pincerna crenilabris — Páll-Gergely et al. 2020: 173.

Material examined.

Indonesia • South Sumatra, Ogan Komering Ulu, Semidang Aji, Suka Merindu (Plot 10); 4°04.11'S, 103°55.34'E; alt. 158 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24144/4 • 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. 24137/15 • South Sumatra, Ogan Komering Ulu, Semidang Aji, Padang Bindu (Plot 4); 4°04.01'S, 103°55.89'E; alt. 111 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24136/1 • South Sumatra, Ogan Komering Ulu, Semidang Aji, Suka Merindu (Plot 7); 4°04.06'S, 103°55.52'E; alt. 126 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24135/40 • South Sumatra, Ogan Komering Ulu, Semidang Aji, Padang Bindu (Plot 13); 4°04.24'S, 103°55.70'E; alt. 170 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24133/13, MZB Gst. 24134/19 • South Sumatra, Ogan Komering Ulu, Semidang Aji, Padang Bindu (Plot 2); 4°04.00'S, 103°55.79'E; alt. 158 m; May-June 2021; A. S. Nurinsiyah leg.; MZB Gst. 24143/1 • South Sumatra, Ogan Komering Ulu, Semidang Aji, Suka Merindu (Plot 6); 4°04.05'S, 103°55.47'E; alt. 123 m; May-June 2021; A. S. Nurinsiyah leg.; MZB 24145/4.

Description (n = 49).

Shells micro size with H = 3.8–5 mm (mean 4.4 mm); D = 3.8–4.8 mm (mean 4.2 mm); HA = 1.5–2 mm (mean 1.7 mm); DA = 1.4–2.7 mm (mean 2.3 mm); 4–5 whorls. Operculum width 1.4–1.5 mm, height 1.4–1.5 mm, concavity / thickness 0.4–0.5 mm. Shell dextral; almost globular with a depressed apex; pale pink or yellowish brown color, not transparent; protoconch smooth, R 1 with ~ 2.25 whorls, with widely-spaced, strong ribs (~ 20–22 ribs on the last half whorl of R 1) and fine spiral striation between the ribs, R 2 short, of ~ 1 / 8 whorl, with ~ 12 ribs, rib density slightly higher than that of R 1, constriction between R 2 and R 3 shallow, R 3 slightly shorter than a 1 / 4 whorl, ribs more widely-spaced on R 3 than on R 1, aperture oblique to shell axis in lateral view, aperture mostly rounded with slight upper incision (at the parieto-palatal corner), and the palatal part of the inner peristome may be slightly edentate, inner and outer peristomes clearly separated, inner peristome thickened and slightly protruding, outer peristome strongly expanding, having a projection on the basal part, and interestingly, turns anteriorly (above the inner peristome) at the upper palatal region, umbilicus rounded, open, very narrow, nearly half covered by peristome; operculum concave, inner surface with a tiny central nipple, outer surface multispiral, without elevated lamella.

Habitat.

Limestone rocks.

Distribution.

The species was previously recorded in western Java (see Páll-Gergely et al. 2020 and references therein). The distribution in Padang Bindu karst is a new record.

Remarks.

Comparing typical Pincerna crenilabris (see photos of the holotype, Fig. 6 a), and the shells collected by us in Sumatra, we could observe some differences in rib density. Namely, on the body whorl of the Sumatran specimens, 35 ribs were counted on the body whorl before the constriction. In contrast, on the photographed holotype, there are ~ 45 ribs on the last whorl behind the constriction. Nevertheless, we interpret these differences as parts of the intrasubspecific variability.

Two subspecies of Pincerna crenilabris were described by van Benthem Jutting (1959), namely Alycaeus crenilabris laevis and Alycaeus crenilabris latecostatus. Since both names were primary homonyms, Páll-Gergely et al. (2020) proposed replacement names for both taxa (i. e., P. crenilabris korintjiensis Páll-Gergely, 2020 and P. crenilabris juttingae Páll-Gergely, 2020, respectively). We examined the photos of the holotype of Pincerna (?) crenilabris korintjiensis (ZMA. MOLL 135672, Fig. 5 d) (described from “ Kajo Aro Estate, Mt. Korintji ”) and confirmed that this is a valid Chamalycaeus species, which differs from P. crenilabris in the more conical shells shape (P. crenilabris is rather globular) and the much denser R 2 ribs. Pincerna crenilabris juttingae is distributed in Brastagi, North Sumatra. No illustrations of this taxon have ever been published. Based on its shell characters (Fig. 6 c), P. crenilabris juttingae differs from the nominotypical subspecies by the smooth R 3, and the absence of the basal projection of the outer peristome, which justifies its distinction as a subspecies.