Dicharax ebrius Páll-Gergely & Auffenberg, 2021

Páll-Gergely, Barna, Hunyadi, András, Grego, Jozef, Reischütz, Alexander & Auffenberg, Kurt, 2021, Nineteen new species of Alycaeidae from Myanmar and Thailand (Gastropoda: Caenogastropoda: Cyclophoroidea), Zootaxa 4973 (1), pp. 1-61 : 28-29

Dicharax ebrius Páll-Gergely & Auffenberg n. sp.

Fig. 21

Material examined. Holotype: Thailand, Mae Hong Son Province, 42 km NW of Pai, Road 1095, 19°32’N, 98°32’E, 750 m a.s.l., 20 Mar. 1988, K. Auffenberg leg., UF 345577 (D: 2.89 mm, H: 1.97 mm) . Paratypes: 22 shells, same data as holotype, UF 551221 . Other material: 9 juvenile shells, same data as holotype, UF 551222 .

Etymology. The dorsal view of the shell of this new species looks like a face of a drunken ( ebrius in Latin) man due to glossy R3 swelling.

Diagnosis. A small Dicharax species with a finely ribbed R1, glossy swelling on R3 situated far from peristome, thickened outer peristome and slightly fringed inner peristome.

Description. Shell off-white to yellowish corneous, slightly translucent; shell outline slightly oval in dorsal view; spire slightly elevated, low conical, body whorl rounded; protoconch low, glossy, 1.25–1.5 whorls; R1 of 1.75–2 whorls, finely, regularly ribbed from beginning, ribs gradually become more widely-spaced toward R1 termination; boundary between R1 and R2 conspicuous due to dense R2 ribs; R2 ribs curved toward aperture, ca. 44–46 ribs present; R2 ribs almost adnate; R2+R3 slightly more than quarter whorl (ca. 100˚); R2 approximately as long as R3 or slightly shorter; boundary between R2 and R3 distinct due to change in sculpture and deep constriction; R3 with prominent, but rounded, glossy swelling situated close to constriction; between swelling and peristome with few fine ribs, in some specimens this area slightly swollen, seemingly forming secondary swelling; aperture strongly oblique to shell axis, rounded with basal incision; boundary between inner and outer peristomes indistinct; inner peristome strong, protruding, expanded, basal and palatal portions slightly fringed, outer peristome expanded, and reflected toward umbilicus; peristome edges merge to form a multi-layered, thickened apertural lip; umbilicus narrow, approximately one fourth of shell width.

Measurements. D: 2.65–2.89 mm, H: 1.85–1.97 mm.

Operculum. Outer surface concave, yellowish corneous, with some traces of a deciduous lamina; inner surface with a small, pointed, low central nipple.

Differential diagnosis. The small shell size, blunt, but prominent, glossy swelling on R3 makes this new species easy to recognize. Dicharax notus (Godwin-Austen, 1914) is similar in overall shell shape, but has blunter, less glossy R3 swelling situated closer to peristome and a rounded aperture.

Due to the weak traces of lower, secondary R3 swelling and overall shell shape, this new species is similar to D. birugosus (Godwin-Austen, 1893) (syn. Alycaeus canaliculus Godwin-Austen, 1914 , see Páll-Gergely et al. 2020) from the Khasi Hills, India. However, the Indian species has shorter R2 and R3, the R2 ribs are more widely-spaced, and prominent secondary swelling.

Distribution. This new species is known only from the type locality ( Fig. 17 ).

Figures

FIGURE 17. Distribution of alycaeid species in northern Thailand and Myanmar. filled circle: Dicharax admirandus Páll- Gergely & Auffenberg, n. sp., empty square: Dicharax ebrius Páll-Gergely & Auffenberg, n. sp., filled triangle: Dicharax gnomus Páll-Gergely, n. sp., filled square: Dicharax mirounga Páll-Gergely, n. sp., inverted empty triangles: Dicharax verruco- sus Páll-Gergely & Hunyadi n. sp., rhombus: Dicharax stuparum Páll-Gergely & Hunyadi, 2018, empty triangle: Metalycaeus anas Páll-Gergely & A. Reischütz, n. sp.

FIGURE 21. Dicharax ebrius Páll-Gergely & Auffenberg, n. sp., A: holotype (UF 345577); B: paratype (UF 551221).