A generic classification of Xenidae (Strepsiptera) based on the morphology of the female cephalothorax and male cephalotheca with a preliminary checklist of species

<jats:p>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:<jats:italic>Sphecixenos</jats:italic><jats:bold>gen. nov.</jats:bold>,<jats:italic>Tuberoxenos</jats:italic><jats:bold>gen. nov.</jats:bold>, and<jats:italic>Deltoxenos</jats:italic><jats:bold>gen. nov.</jats:bold>Five previously described genera are removed from synonymy:<jats:italic>Tachytixenos</jats:italic>Pierce, 1911,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos</jats:italic>Kogan &amp; Oliveira, 1966,<jats:bold>stat. res.</jats:bold>;<jats:italic>Leionotoxenos</jats:italic>Pierce, 1909,<jats:bold>stat. res.</jats:bold>;<jats:italic>Eupathocera</jats:italic>Pierce, 1908,<jats:bold>stat. res.</jats:bold>; and<jats:italic>Macroxenos</jats:italic>Schultze, 1925,<jats:bold>stat. res.</jats:bold>One former subgenus is elevated to generic rank:<jats:italic>Nipponoxenos</jats:italic>Kifune &amp; Maeta, 1975,<jats:bold>stat. res.</jats:bold><jats:italic>Monobiaphila</jats:italic>Pierce, 1909,<jats:bold>syn. nov.</jats:bold>and<jats:italic>Montezumiaphila</jats:italic>Brèthes, 1923,<jats:bold>syn. nov.</jats:bold>are recognized as junior synonyms of<jats:italic>Leionotoxenos</jats:italic>Pierce, 1909,<jats:bold>stat. res.</jats:bold><jats:italic>Ophthalmochlus</jats:italic>Pierce, 1908,<jats:bold>syn. nov.</jats:bold>,<jats:italic>Homilops</jats:italic>Pierce, 1908,<jats:bold>syn. nov.</jats:bold>,<jats:italic>Sceliphronechthrus</jats:italic>Pierce, 1909,<jats:bold>syn. nov.</jats:bold>, and Ophthalmochlus (Isodontiphila) Pierce, 1919,<jats:bold>syn. nov.</jats:bold>are recognized as junior synonyms of<jats:italic>Eupathocera</jats:italic>Pierce, 1908,<jats:bold>stat. res.</jats:bold>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:<jats:italic>Tachytixenos indicus</jats:italic>Pierce, 1911,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos acinctus</jats:italic>Kogan &amp; Oliveira, 1966,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos araujoi</jats:italic>(Oliveira &amp; Kogan, 1962),<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos bahiensis</jats:italic>Kogan &amp; Oliveira, 1966,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos brasiliensis</jats:italic>Kogan &amp; Oliveira, 1966,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos fluminensis</jats:italic>Kogan &amp; Oliveria, 1966,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos myrapetrus</jats:italic>Trois, 1988,<jats:bold>stat. res.</jats:bold>;<jats:italic>Brasixenos zikani</jats:italic>Kogan &amp; Oliveira, 1966,<jats:bold>stat. res.</jats:bold>;<jats:italic>Leionotoxenos hookeri</jats:italic>Pierce, 1909,<jats:bold>stat. res.</jats:bold>;<jats:italic>Leionotoxenos jonesi</jats:italic>Pierce, 1909,<jats:bold>stat. res.</jats:bold>;<jats:italic>Leionotoxenos louisianae</jats:italic>Pierce, 1909,<jats:bold>stat. res.</jats:bold>;<jats:italic>Eupathocera luctuosae</jats:italic>Pierce, 1911,<jats:bold>stat. res.</jats:bold>;<jats:italic>Eupathocera lugubris</jats:italic>Pierce, 1909,<jats:bold>stat. res.</jats:bold>;<jats:italic>Macroxenos piercei</jats:italic>Schultze, 1925,<jats:bold>stat. res.</jats:bold>New generic combinations are proposed for 51 species:<jats:italic>Leionotoxenos arvensidis</jats:italic>(Pierce, 1911),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos bishoppi</jats:italic>(Pierce, 1909),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos foraminati</jats:italic>(Pierce, 1911),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos fundati</jats:italic>(Pierce, 1911),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos huastecae</jats:italic>(Székessy, 1965),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos itatiaiae</jats:italic>(Trois, 1984),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos neomexicanus</jats:italic>(Pierce, 1919),<jats:bold>comb. nov.</jats:bold>;<jats:italic>Leionotoxenos prolificum</jats:italic>(Teson &amp; Remes Lenicov, 1979),<jats:bold>comb. nov.</jats:b ...