Arpedium ERICHSON 1839

Zanetti, A., 2008, Synonymies in the European Omaliinae, with notes on distribution (Coleoptera: Staphylinidae), Linzer biologische Beiträge 40 (1), pp. 979-992 : 985

Genus Arpedium ERICHSON 1839

Arpedium ERICHSON 1839 : type species: Omalium quadrum GRAVENHORST 1806

Eucnecosum REITTER 1909: type species: Omalium brachypterum GRAVENHORST 1802 ; synonymy confirmed, not subgenus.

C o m m e n t s: Eucnecosum REITTER 1909 was described as subgenus of Arpedium ERICHSON 1909 based on the following characters: Arpedium – anterior part of body without pubescence, strongly punctured, head with parallel temples and deep pits on vertex, elytra long; Eucnecosum – dorsal surface with fine pubescence, head and pronotum with fine puncuration, the first almost smooth, furrows on vertex fine and shortly impressed, elytra short, body flattened, yellowish-brown. Eucnecosum was considered a valid genus by LOHSE (1963) and this state was accepted in the subsequent literature. Recently ASSING (2007) described Arpedium ludgeri , a new species from Kyrgyzstan which "combines characters typically observed in Arpedium with those of Eucnecosum, thus rendering the separation of these taxa on the generic level doubtful". He wrote also: "The characters indicated in the literature (...) to distinguish the two taxa (e. g. presence/absence of microsculpture, length and density of pubescence, length of antennae, relative length of palpomeres) do not seem to justify such a distinction. Finally, I have been unable to appreciate the presence/absence of a subocular ridge as a useful character." He argued also that "there is little doubt that Eucnecosum will eventually have to be treated as a subgenus again or may even have to be synonymised with Arpedium . Such changes, however, should be based on a thorough phylogenetic study of these taxa, which is not within the scope of the present paper". I think that this argument should be used in the reverse sense, i.e. that without phylogenetical study no serious reason to maintain Eucnecosum as a valid genus exists.