Periscelididae Oldenberg, 1914

Mathis, Wayne N. & Freidberg, Amnon, 2012, Periscelis stuckenbergi sp. n., the first record of the genus from the Afrotropical Region (Diptera: Periscelididae: Periscelidinae), African Invertebrates 53 (1), pp. 231-231 : 232

Family Periscelididae Oldenberg, 1914

Diagnosis: Adult. Small flies, body length 2.5–5.0 mm, moderately broad to slender. Head: Width equal to that of thorax, distinctly wider than high; frons wider than long, becoming narrower toward anterior margin, bearing 1 or 2 fronto­orbital setae; postocellar setae present and divergent or absent. Pedicel cap­like and with a dorsal cleft, bearing 1 or more dorsoapical setae; flagellomere 1 frequently sharply deflexed, extended from ventral surface of pedicel; arista bipectinate. Face uniformly sclerotised and arched, setose laterally. Thorax: Dorsocentral setae usually 2 (0+2), sometimes 1 (0+1), none presutural; posterior intra­alar seta reduced; scutellum with 1 or 2 pairs of marginal setae; scutellar disc bare; anepisternal seta usually lacking (present in Planinasus Cresson, 1914 ). Wing: Hyaline or with infuscate markings. Subcosta rudimentary, not reaching costal margin, and not fused apically with R 1; no costal breaks (a weakness in the costa just apicad of the humeral crossvein in Planinasus ); costa extended to vein R 4+5 or M; cell dm with shallow fold running entire length; cell cup present, although CuA 2 either well developed or extremely reduced. Mid tibia bearing prominent, apicoventral seta. Classification: The concept of Periscelididae , as adopted here, follows McAlpine (1978, 1983) and includes a few genera previously assigned to Aulacigastridae Duda, 1924 ( Cyamops , Planinasus, Stenocyamops Papp, 2006 and Stenomicra ). McAlpine characterised Periscelididae primarily by the cap­like pedicel, which has a dorsal cleft, and its relationship to the first flagellomere. Although these characters are common to all Periscelididae , they also occur in Neurochaetidae McAlpine, 1978 ( Woodley 1982) and some other acalyptrate genera. In a recent phylogenetic study of the Opomyzoidea Fallén, 1820, using 28S ribosomal DNA and CAD (rudimentary) genes ( Winkler et al. 2010), Stenomicra, Cyamops and Planinasus grouped consistently with moderate support with the genus Aulacigaster Macquart, 1835 and not with Periscelidinae . Moreover, the same analysis failed to find any support for a sister­group relationship between Periscelididae and Neurochaetidae . Their results highlight the need to study the phylogeny of these groups in greater detail and using different suites of characters.