Genus Metalycaeus Pilsbry, 1900

Alycaeus (Metalycaeus) Pilsbry, 1900: 382 .

Type species. Alycaeus (Metalycaeus) melanopoma Pilsbry, 1900 (synonym of Alycaeus nipponensis Reinhardt, 1877, see Minato 1988), by subsequent designation (Thiele 1929).

Diagnosis. Metalycaeus is characterized by the presence of spiral striation on both the protoconch and teleoconch (Páll-Gergely et al. 2017, 2020). However, some shells of one Japanese species lacks spiral striation on the protoconch. Here we report a species ( M. pygmachos n. sp.) lacking spiral striation on the entire shell, but based on other characters, is best assigned to this genus. Thus, examination of shell characters other than the spirally striated protoconch is also necessary.