On the taxonomy and natural history of Oxypoda brachyptera and O. tarda (Coleoptera: Staphylinidae: Aleocharinae).

Abstract

Based on a revision of types and additional material, Oxypoda brachyptera (Stephens, 1832) and O. tarda Sharp, 1871, two species with a controversial and confusing taxonomic history, are regarded as distinct species, redescribed, and illustrated. A lectotype is designated for Oxypoda tarda. Numerous field studies conducted in northwestern Germany during the period from 1981 through 2001 yielded approximately 8,500 adult specimens of O. brachyptera and O. tarda. Based on these data, as well as on anatomical studies, the life histories of both species, including their seasonal activity, seasonal density, reproduction periods, duration of pre-imaginal development, and pupal emergence, are investigated. Both species are epigeically active from spring through autumn, develop without diapause, and hibernate in the adult stage. In contrast to Oxypoda tarda, which has only one generation per year, O. brachyptera is apparently bivoltine. Both species are generally found in open, unshaded biotopes. Nevertheless, regarding their respective habitats, they are distinctly segregated. While O. brachyptera was recorded from drier and wamer habitats on sandy or calcareous soils, O. tarda usually occurs in moist localities on heavier soils. Rarely, they were found to occur syntopically. Both species are wing-dimorphic, the macropterous morph being distinctly rarer than the micropterous morph; the dimorphism is not sex-related.

Keywords

Coleoptera, Staphylinidae, Aleocharinae, Oxypodini, Oxypoda, West Palaearctic, taxonomy, ecology, lectotype designations, natural history, seasonal activity, seasonal density, oviposition, flight muscles, wing dimorphism.