Omus Eschscholtz, 1829

Bousquet, Yves, 2012, Catalogue of Geadephaga (Coleoptera, Adephaga) of America, north of Mexico, ZooKeys 245, pp. 1-1722 : 199

Genus Omus Eschscholtz, 1829

Omus Eschscholtz, 1829: 3. Type species: Omus californicus Eschscholtz, 1829 by monotypy. Etymology. From the Greek omos (cruel), possibly alluding to the apparent ferocious habits of the species in the eyes of Eschscholtz [masculine].

Leptomus Casey, 1914: 1. Type species: Omus submetallicus Horn, 1869 by original designation. Synonymy established by Horn (1915: 443). Etymology. From the Greek leptos (fine, small, thin, delicate) and the generic name Omus [q.v.] [masculine].

Megomus Casey, 1914: 1. Type species: Omus dejeanii Reiche, 1838 by original designation. Synonymy established by Horn (1915: 443). Etymology. From the Greek megas (large) and the generic name Omus [q.v.] [masculine].

Diversity.

Five species in western North America inhabiting the Pacific coastal lowlands and the mountain slopes, including those of the Cascade and Sierra Nevada ranges.

Identification.

Casey, between 1897 and 1924, described so many forms in this genus (90 species-group taxa) that at the time of his death in 1925 it was virtually impossible to identify members of Omus . Cazier (1942) wrote a detailed monographic revision of the genus and recognized three species ( Anisodactylus californicus , Anisodactylus dejeanii , and Anisodactylus submetallicus ) with four subspecies for Anisodactylus californicus . He also provided keys for the identification of the taxa. Unfortunately his thesis was not published. In his thesis on the cicindelids of the Pacific Northwest, Leffler (1979a) followed Cazier’s (1942) conclusions concerning the taxonomy of Omus except that he recognized a fourth species, according specific rank to Omus audouini considered a synonym of Omus californicus californicus by Cazier. Leffler (1979a) provided a key for the separation of the species but his work also remained unpublished. Subsequently, a new species was described by van den Berghe in 1994. The field guide of Pearson et al. (2006: 23) includes a key to all five species.