Metalycaeus pygmachos Páll-Gergely & Hunyadi, 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 : 55-56

Metalycaeus pygmachos Páll-Gergely & Hunyadi n. sp.

Fig. 42

Material examined. Holotype: Myanmar, Mandalay State, near Maha Nandamu Peik Chin Myaung Cave & Waterfall, 22°05.762’N, 96°37.087’E, 740 m a.s.l. (locality code: 2018/66), 19 Oct. 2018, A. Hunyadi leg., HNHM 104866 (D: 4.8 mm, H: 2.91 mm) . Paratype: 1 shell, same data as holotype, HA .

Etymology. The specific epithet pygmachos (πυγμαχος: Greek for boxer) refers to the peculiarly shaped R3 resembling a boxer’s face after being punched.

Diagnosis. A large Metalycaeus species with a long, swollen R2 having widely-spaced slim ribs, and a complex, conspicuous swelling on R3.

Description. Shell off-white, although both available shells are eroded; shell outline oval in dorsal view due to conspicuously swollen R2; spire slightly elevated, domed; body whorl rounded; protoconch low, finely granular, spiral striae lacking, 1.25 whorls; R1 of 1.75–2 whorls, with strong, elevated, equidistant ribs and some faint, dense spiral striation; boundary between R1 and R2 not conspicuous because R1 and R2 ribs identical in shape and density; R2 with ca. 30–32 R2 ribs; R2+R3 almost half whorl (ca. 150–160˚); R2 slightly longer than R3; boundary between R2 and R3 indicated with very deep constriction; R3 characterized by very complex swelling strongly depressed dorsolaterally; this elongate depression parallel to constriction, corresponds with irregularly swollen ridge visible in oblique view in aperture; depression results in a U-shaped R3 swelling; upper rim of U, visible in dorsal view, more swollen than narrower lower rim, visible in lateral view; additional small depression just anterior to upper swollen rim, i.e. between upper, swollen rim and peristome, corresponding to a separate, knob-like swelling inside aperture; aperture strongly oblique to shell axis, rounded with slight upper and lower incisions; boundary between inner and outer peristomes barely discernible, inner peristome slightly protruding and expanded, outer peristome much stronger, wider, expanded, and reflected toward umbilicus, wide distance between inner peristome and edge of outer peristome resulting in strongly thickened lip; umbilicus relatively narrow, approximately less than one third of shell width.

Measurements. 4.8–5.1 mm, H: 2.91–2.98 mm.

Operculum. Unknown.

Differential diagnosis. The peculiarly shaped R3 swelling is a unique feature distinguishing this species from all Chamalycaeus and Metalycaeus species.

Distribution. This new species is known only from the type locality ( Fig. 5 ).

Remarks. This species is classified in the genus Metalycaeus due to its large size and the “depressed swelling” on R3 as in other Metalycaeus species. The lack of spiral striation on the protoconch is considered a secondary reduction.

Figures

FIGURE 5. Distribution of alycaeid species. Inverted empty triangle: Dicharax cyclostoma Páll-Gergely, n. sp., empty triangle: Chamalycaeus spiratus Páll-Gergely, n. sp., filled triangle: Metalycaeus bicarinatus Páll-Gergely & Hunyadi, n. sp., inverted filled triangles: Chamalycaeus erawan Páll-Gergely & Hunyadi n. sp., empty circles: Metalycaeus aries Páll-Gergely & Auffenberg, n. sp., filled circles: Metalycaeus heudei (Bavay & Dautzenberg, 1900) (the one in the north indicates the type locality of Alycaeus kengtungensis Godwin-Austen, 1914), square: Metalycaeus pygmachos Páll-Gergely & Hunyadi, n. sp.

FIGURE 42. Metalycaeus pygmachos Páll-Gergely & Hunyadi, n. sp., holotype (HNHM 104866).