Trixoscelididae Hendel, 1916

Jindřich Roháček

Department of Entomology, Silesian Museum, Tyršova 1, CZ-746 01 Opava, Czech Republic; rohacek@szmo.cz

Minute to small (1.5-3.5 mm), rather stout, usually dark flies with densely microtomentose body (or at least thorax). Head rounded; its chaetotaxy characterised by the absence of interfrontal setulae, by the ocellar setae arising outside the ocellar triangle, and by the 2 fronto-orbital setae. Prosternum setulose;  proepimeral (propleural) setulae generally absent. Thoracic setae rich, usually with 5 dorsocentral setae. Wing often with infuscated patterns. Costa strongly spinulose, with subcostal break; subcosta complete, ending near R1, cell bm closed, cell cup short. All tibiae with dorsal preapical setae. Male genitalia with small cerci, distinctive gonostyli, short hypandrium, large phallophore and complex distiphallus; epiphallus absent. Female postabdomen with 7th tergum and sternum fused or closely attached, 8th sternum with lateral setulose lobes, and with 3 (2+1) spermathecae. The unknown larvae are probably saprophagous; two Trixoscelis species have been reared from a blackbird's nest. Trixoscelis species are thermophilous and adults can be swept from vegetation in warm, sandy, steppe and forest steppe habitats.

The family has often been considered, even recently, as a tribe or subfamily of the Heleomyzidae, but it is here ranked as a family following the Fauna Europaea (Woźnica 2004). Altogether 26 species belonging to the sole European genus Trixoscelis Rondani, 1856 have been recorded in Europe and adjacent areas as included in the Fauna Europaea (Woźnica 2004); 5 are listed in the present checklist (5 in the Czech Republic, 4 in Bohemia, 5 in Moravia, and 4 in Slovakia). Since the last version of the checklist, the number of species in the Czech Republic has increased by 1 (0 in Bohemia, 1 in Moravia), but there have been no additions for Slovakia. The family was treated by Papp (1998) within the framework of the “Heleomyzoid families”, which included a key to the three Palaearctic genera. There is no identification tool for the European species of Trixoscelis; the species occurring in Central Europe can be identified with the keys in Hackman (1970) and Soós (1981). The family has received little attention in the Czech Republic and Slovakia; references to the scattered previous records can be found in Roháček and Barták (2001) and Roháček et al. (2005). The nomenclature of this checklist follows that in the Fauna Europaea (Woźnica 2004).

References

[1] Hackman W. 1970: Trixoscelididae (Diptera) from southern Spain and description of a new species from northern Europe. Entomologica scandinavica 1: 127-134.

[2] Papp L. 1998: 3.41. Families of Heleomyzoidea. In Papp L. & Darvas B. (eds): Contributions to a Manual of Palaearctic Diptera. Vol. 3., Higher Brachycera. Science Herald, Budapest, pp. 425-455.

[3] Roháček J. & Barták M. 2001: Trixoscelididae. In Barták M. & Vaňhara J. (eds): Diptera in an industrially affected region (north-western Bohemia, Bílina and Duchcov environs), II. Folia Facultatis Scientiarum Naturalium Universitatis Masarykianae Brunensis, Biologia 105: 407-409.

[4] Roháček J., Kubík Š. & Barták M. 2005: Trixoscelididae. In Barták M. & Kubík Š. (eds): Diptera of Podyjí National Park and its Environs. Česká zemědělská univerzita v Praze, Praha, pp. 332-333.

[5] Soós Á. 1981: Trixoscelididae - Homoklegyek, Chyromyidae –  Kéneslegyek. Fauna Hungariae, 149. Akadémiai Kiadó, Budapest, pp. 78-93.

[6] Woźnica A.J. 2004: Fauna Europaea: Trixoscelididae. In Pape T. (ed.): Fauna Europaea: Diptera, Brachycera. Fauna Europaea version 1.1, http://www.faunaeur.org.