Alycaeus Gray, 1850

Aravind, Neelavar Ananthram & Páll-Gergely, Barna, 2023, Two Extraordinary Alycaeid Species From Northeastern India (Gastropoda: Caenogastropoda: Cyclophoroidea), Acta Zoologica Academiae Scientiarum Hungaricae 69 (4), pp. 353-363 : 356-357

Genus Alycaeus Gray, 1850

Type species: Cyclostoma gibbum Eydoux, 1838 [= Alycaeus eydouxi Venmans, 1956 ]).

Remarks: Among the genera distributed in the Himalayas, it cannot be included in Dicharax Kobelt & Möllendorff, 1900 (type species: Alycaeus hebes Benson, 1857 ) because Dicharax species are mostly depressed (not conical) and nearly all species lack spiral striation (but there are exceptions, see e.g. PÁLL-GERGELY et al. 2021). Cycloryx species are much smaller, with dominant radial sculpture and a very short R2. Metalycaeus Pilsbry, 1900 (type species: Alycaeus melanopoma Pilsbry, 1900 = Alycaeus nipponensis Reinhardt, 1877 ) species are characterized by a spirally striated protoconch. The only possible candidate would be Chamalycaeus Möllendorff, 1897b (type species: Alycaeus fruhstorferi Möllendorff, 1897 b ), which also lack spiral striation on the protoconch, but Chamalycaeus species are usually not conical, are mostly whitish, and possess stronger radial sculpture.

Based on the general shell and aperture shape and the long R2, this new species fits perfectly in the genus Alycaeus . Nevertheless, Alycaeus species are only known from southern Thailand, Peninsular Malaysia, northern and central Laos and northern and central Vietnam ( PÁLL-GERGELY et al. 2020, PÁLL-GERGELY 2023). Pincerna mouhoti (L. Pfeiffer, 1862) and Pincerna vanbuensis (Bavay et Dautzenberg, 1900) , inhabiting northern Laos and northern Vietnam (see Fig. 4 ), may belong to Alycaeus , but has been included in the genus Pincerna in the latest revision. Therefore, A. himalayae sp. n. is so far the westernmost distribution of the genus.

Figures

Fig. 4. Distribution of the genus Alycaeus Gray, 1850 (based on PÁLL-GERGELY et al. 2020 and PÁLL-GERGELY 2023). Dark grey area: Alycaeus s. str., Light grey area: distribution of Pincerna mouhoti (L. Pfeiffer, 1862) and Pincerna vanbuensis (Bavay et Dautzenberg, 1900),