A generic classification of Xenidae (Strepsiptera) based on the morphology of the female cephalothorax and male cephalotheca with a preliminary checklist of species
Authors: Benda Daniel , Pohl Hans , Nakase Yuta , Beutel Rolf , Straka Jakub 
Published: April 2022

The generic taxonomy and host specialization of Xenidae have been understood differently by previous authors. Although the recent generic classification has implied a specialization on the level of host families or subfamilies, the hypothesis that each xenid genus is specialized to a single host genus was also previously postulated. A critical evaluation of the classification of the genera of Xenidae is provided here based on morphology in accordance with results of recent molecular phylogenetic studies. External features of the female cephalothoraces and male cephalothecae were documented in detail with different techniques. Diagnoses and descriptions are presented for all 13 delimited genera. The earliest diverging genera are usually well characterized by unique features, whereas deeply nested genera are usually characterized by combinations of characters. Three new genera are described:Sphecixenosgen. nov.,Tuberoxenosgen. nov., andDeltoxenosgen. nov.Five previously described genera are removed from synonymy:TachytixenosPierce, 1911,stat. res.;BrasixenosKogan &amp; Oliveira, 1966,stat. res.;LeionotoxenosPierce, 1909,stat. res.;EupathoceraPierce, 1908,stat. res.; andMacroxenosSchultze, 1925,stat. res.One former subgenus is elevated to generic rank:NipponoxenosKifune &amp; Maeta, 1975,stat. res.MonobiaphilaPierce, 1909,syn. nov.andMontezumiaphilaBrèthes, 1923,syn. nov.are recognized as junior synonyms ofLeionotoxenosPierce, 1909,stat. res.OphthalmochlusPierce, 1908,syn. nov.,HomilopsPierce, 1908,syn. nov.,SceliphronechthrusPierce, 1909,syn. nov., and Ophthalmochlus (Isodontiphila) Pierce, 1919,syn. nov.are recognized as junior synonyms ofEupathoceraPierce, 1908,stat. res.A preliminary checklist of 119 described species of Xenidae with information on their hosts and distribution is provided. The following 14 species are recognized as valid and restituted from synonymy:Tachytixenos indicusPierce, 1911,stat. res.;Brasixenos acinctusKogan &amp; Oliveira, 1966,stat. res.;Brasixenos araujoi(Oliveira &amp; Kogan, 1962),stat. res.;Brasixenos bahiensisKogan &amp; Oliveira, 1966,stat. res.;Brasixenos brasiliensisKogan &amp; Oliveira, 1966,stat. res.;Brasixenos fluminensisKogan &amp; Oliveria, 1966,stat. res.;Brasixenos myrapetrusTrois, 1988,stat. res.;Brasixenos zikaniKogan &amp; Oliveira, 1966,stat. res.;Leionotoxenos hookeriPierce, 1909,stat. res.;Leionotoxenos jonesiPierce, 1909,stat. res.;Leionotoxenos louisianaePierce, 1909,stat. res.;Eupathocera luctuosaePierce, 1911,stat. res.;Eupathocera lugubrisPierce, 1909,stat. res.;Macroxenos pierceiSchultze, 1925,stat. res.New generic combinations are proposed for 51 species:Leionotoxenos arvensidis(Pierce, 1911),comb. nov.;Leionotoxenos bishoppi(Pierce, 1909),comb. nov.;Leionotoxenos foraminati(Pierce, 1911),comb. nov.;Leionotoxenos fundati(Pierce, 1911),comb. nov.;Leionotoxenos huastecae(Székessy, 1965),comb. nov.;Leionotoxenos itatiaiae(Trois, 1984),comb. nov.;Leionotoxenos neomexicanus(Pierce, 1919),comb. nov.;Leionotoxenos prolificum(Teson &amp; Remes Lenicov, 1979),comb. nov.;Leionotoxenos robertsoni(Pierce, 1911),comb. nov.;Leionotoxenos tigridis(Pierce, 1911),comb. nov.;Leionotoxenos vigili(Brèthes, 1923),comb. nov.;Eupathocera argentina(Brèthes, 1923),comb. nov.;Eupathocera auripedis(Pierce, 1911),comb. nov.;Eupathocera bucki(Trois, 1984),comb. nov.;Eupathocera duryi(Pierce, 1909),comb. nov.;Eupathocera erynnidis(Pierce, 1911),comb. nov.;Eupathocera fasciati(Pierce, 1909),comb. nov.;Eupathocera fuliginosi(Brèthes, 1923),comb. nov.;Eupathocera inclusa(Oliveira &amp; Kogan, 1963),comb. nov.;Eupathocera insularis(Kifune, 1983),comb. nov.;Eupathocera mendozae(Brèthes, 1923),comb. nov.;Eupathocera piercei(Brèthes, 1923),comb. nov.;Eupathocera striati(Brèthes, 1923),comb. nov.;Eupathocera taschenbergi(Brèthes, 1923),comb. nov.;Eupathocera westwoodii(Templeton, 1841),comb. nov.;Macroxenos papuanus(Székessy, 1956),comb. nov.;Sphecixenos abbotti(Pierce, 1909),comb. nov.;Sphecixenos astrolabensis(Székessy, 1956),comb. nov.;Sphecixenos dorae(Luna de Carvalho, 1956),comb. nov.;Sphecixenos erimae(Székessy, 1956),comb. nov.;Sphecixenos esakii(Hirashima &amp; Kifune, 1962),comb. nov.;Sphecixenos gigas(Pasteels, 1950),comb. nov.;Sphecixenos kurosawai(Kifune, 1984),comb. nov.;Sphecixenos laetum(Ogloblin, 1926),comb. nov.;Sphecixenos orientalis(Kifune, 1985),comb. nov.;Sphecixenos reticulatus(Luna de Carvalho, 1972),comb. nov.;Sphecixenos simplex(Székessy, 1956),comb. nov.;Sphecixenos vanderiisti(Pasteels, 1952),comb. nov.;Tuberoxenos altozambeziensis(Luna de Carvalho, 1959),comb. nov.;Tuberoxenos sinuatus(Pasteels, 1956),comb. nov.;Tuberoxenos sphecidarum(Siebold, 1839),comb. nov.;Tuberoxenos teres(Pasteels, 1950),comb. nov.;Tuberoxenos tibetanus(Yang, 1981),comb. nov.;Deltoxenos bequaerti(Luna de Carvalho, 1956),comb. nov.;Deltoxenos bidentatus(Pasteels, 1950),comb. nov.;Deltoxenos hirokoae(Kifune &amp; Yamane, 1992),comb. nov.;Deltoxenos iwatai(Esaki, 1931),comb. nov.;Deltoxenos lusitanicus(Luna de Carvalho, 1960),comb. nov.;Deltoxenos minor(Kifune &amp; Maeta, 1978),comb. nov.;Deltoxenos rueppelli(Kinzelbach, 1971a),comb. nov.;Xenos ropalidiae(Kinzelbach, 1975),comb. nov.Xenos minorKinzelbach, 1971a,syn. nov.is recognized as a junior synonym ofX. vesparumRossi, 1793.Ophthalmochlus duryiPierce, 1908,nomen nudumandEupathocera lugubrisPierce, 1908,nomen nudumare recognized as nomina nuda and therefore unavailable in zoological nomenclature. The species diversity of Xenidae probably remains poorly known: the expected number of species is at least twice as high as the number presently described.