Revision of the Cousya species of the West Palaearctic Region (Coleoptera: Staphylinidae: Aleocharinae)

Abstract Species of the genus Cousya Mulsant & Rey, 1875 and five previously unrevised species of Ocyusa Kraatz, 1856 of the West Palaearctic region including Middle Asia are revised. In total, 19 species of Cousya are recognized, with one additional species of which no material was available of doubtful identity and generic affiliations. Three or four additional species remain unnamed for want of males. Only two species, O. maura (Erichson, 1837) and O. picina (Aubé, 1850), remain in Ocyusa. Four species are newly described: Cousya acris n. sp. (South Greece, South Turkey, Cyprus, Lebanon); C. struyvei n. sp. (South Spain); C. pauli n. sp. (Southwest Turkey); C. sufflata n. sp. (Greece: South Pelopónnisos). Redescriptions are provided for Cousya and ten of its species. All the Cousya species and most of the species moved to other genera are illustrated. Eleven synonymies are proposed: Cousya bicolor (Bernhauer, 1900) = C. mirabilis Assing, 2011, n. syn. ; C. defecta (Mulsant & Rey, 1875) = C. humicola Fagel, 1965, n. syn. ; C. longitarsis (Thomson, 1867) = C. rugipennis (J. Sahlberg, 1890) n. syn. (previously a synonym of Oxypoda funebris Kraatz, 1856), = C. peezi Scheerpeltz, 1957, n. syn. ; C. nigrata (Fairmaire & Laboulbène, 1856) = C. cephallenica (Scheerpeltz, 1931), n. syn. , = C. nitidiventris Fagel, 1958, n. syn. , = C. lakloukensis Fagel, 1965, n. syn. ; C. schuelkei Assing, 2007 = C. planicollis Assing, 2011, n. syn. ; C. bimaculata (Fauvel, 1899) = C. vaulogeri (Bernhauer, 1936), n. syn. ; Oxypoda flavicornis Kraatz, 1856 = Ocyusa beieri Scheerpeltz, 1931, n. syn. ; Ocyusa pellax Peyerimhoff, 1919 = Oxypoda argus Normand, 1935, n. syn. Six new binomina are established: Cousya dissoluta (Eppelsheim, 1888), n. comb. (ex Ocyusa); C. praecox (Eppelsheim, 1888), n. comb. (ex Ocyusa); Oxypoda picta Mulsant & Rey, 1875, n. comb. (ex Cousya);Oxypoda pellax (Peyerimhoff, 1919), n. comb. (ex Ocyusa);Oxypoda heydeni (Eppelsheim, 1879), n. comb. (ex Ocyusa);Tectusa uhligi (Pace, 1987), n. comb. (ex Cousya). The material labelled as types of Cousya uhligi is composed of three species, all of them belonging to Tectusa Bernhauer, 1899. One of them is Tectusa pirinica n. sp. (Bulgaria: Pirin Planina). Four Bulgarian species of Tectusa, including T. pirinica, are illustrated. “Ocyusa” apicalis Normand, 1935 is not congeneric with the type species of Ocyusa and treated as Oxypodina incertae sedis. A neotype is designated for Ocyusa defecta Mulsant & Rey, 1875. Lectotypes are designated for Cousya peezi Scheerpeltz, 1957, Ocyusa eppelsheimi Bernhauer, 1902, O. araxis Bernhauer, 1902, O. bicolor Bernhauer, 1900, Homalota dissoluta Eppelsheim, 1888, H. praecox Eppelsheim, 1888, and Ocyusa ferdinandicoburgi Rambousek, 1909. A catalogue and a key to the Cousya species of the West Palaearctic region are provided. The species of Cousya are assigned to two species groups, the C. nigrata group (eleven species) and the C. crocea group (eight species). While the species of the C. nigrata group are fully winged and widespread, those of the C. crocea group are partly incapable of flight and have restricted distributions; six of them have been recorded only from their respective type localities. The distributions of all the Cousya species are mapped. Available evidence suggests that at least the species of the C. nigrata group reproduce in autumn (most species in a subterranean habitat), have their preimaginal development in winter and early spring, emerge from the pupa and disperse in spring, and spend the warmer seasons either in estivation or in a subterranean habitat. A biased sex ratio (males rarer than females) was observed in two species. It is particularly pronounced in C. nigrata: only 15 % of the sexed specimens are males. Not a single male was found in the north of its range, suggesting that the species is parthenogenetic in this region.