Heterocheylidae Tragardh 1940

HETEROCHEYLIDAE Trägårdh, 1940 A small family with one genus and 26 species. All species are associated with the Passalidae (Lombardini 1926; Trägårdh 1950a; Womersley 1960; Schuster and Lavoipierre 1970; Reinert 1973; Delfinado and Baker 1975; Barrios-Torres and Villegas-Gusmán 2015; Katlav et al. 2020). Twenty-one species of Heterocheylidae were collected from 56 species of Passalidae belonging to 24 genera. Five species were collected from unidentified Passalidae. Heterocheylus proximus Schuster and Lavoipierre, 1970 and H. rugosus Schuster and Lavoipierre, 1970 were collected from 10 species of passalids, and H. cavagnaroi Schuster and Lavoipierre, 1970 and H. keiferi Schuster and Lavoipierre, 1970 were collected from four species of passalids (Tables 2, 15). Fourteen species of heterocheylids were collected from only one species of host each. Heterocheylidae are characterised by a pronounced host specificity. None of the Heterocheylidae species were caught on the same host species, except H. bengalensis Schuster and Lavoipierre, 1970. Some passalids have more than one species: H. parvus Schuster and Lavoipierre, 1970 and H. thai Schuster and Lavoipierre, 1970 were collected from Leptaulax bicolor; H. nixus Schuster and Lavoipierre, 1970 and H. rugosus Schuster and Lavoipierre, 1970 were collected from Protomocoelus australis (Boisduval, 1835); and H. keiferi Schuster and Lavoipierre, 1970 and H. proximus Schuster and Lavoipierre, 1970 were collected from Passalus interstitialis (Tables 2–6, 15). On 26 species of Passalidae only Heterocheylidae were found: Aulacocyclus papuanus (Heller, 1910), A. rosenbergi Kaup, 1868, Aceraius illegalis (Kuwert, 1901), Cetejus peltostictus (Kaup, 1868), Ciceronius morbillosus (Klug, 1832), Didimus haroldi Kuwert, 1908, Gonatas major Kuwert, 1891, G. minimus (Kuwert, 1891), G. minor Gravely, 1918, G. pumilio (Kaup, 1868), G. schellongi Kuwert, 1891, Macrolinus rotundifrons Kaup, 1871, M. sulciperfectus Kaup, 1891, Ophrygonius cantori (Percheron, 1844), Passalus anguliferus Percheron, 1835, P. binominatus Percheron, 1841, P. clypelomeleus Kuwert, 1891, P. considerabilis (Kuwert, 1891), P. mucronatus Burmeister, 1847, P. plicatus Percheron, 1835, P. spiniger Bates, 1886, Paxillus pleuralis Luederwaldt, 1937, Popilius haagi (Kaup, 1866), Solenocyclus exaratus Klug, 1832, Stephanocephalus hostilis (Percheron, 1841), and Trichostigmus thoreyi (Kaup, 1868).