A critical study of the suborder Myxophaga, with a taxonomic revision of the Brazilian Torridincolidae and Hydroscaphidae (Coleoptera)

Abstract

The suborder Myxophaga Crowson, 1955, at present including the families Torridincolidae, Hydroscaphidae, Sphaeridae and Lepiceridae, is critically analyzed in relation to the other three suborders of Coleoptera. The study is heavily based on nexo forms of Torridincolidae and Hydroscaphidae discovered in recent years in southeastern Brazil by the author, and which are described in the taxonomic part. Torridincolidae are studied in more depth than the other families, and new data on internal and external anatomy of adults and immature stages are supplied. The author concludes that Myxophaga is a valid suborder of Coleoptera, its components representing primitive beetles, which are to be considered as somewhat intermediate between the two main suborders, Adephaga and Polyphaga. As already pointed out by some earlier authors, but substantiated with more examples, Myxophaga share important characters with both suborders. Ecological and geographic data available are analyzed. In the taxonomic part the following taxa are described: 1. Torridincolidae. Hintonia, nom. nov., for Ptyopteryx Reichardt & Costa, 1967 (nec Ptyopteryx Kolenati, 1848). A second species is added to this formerly monotypic genus: castalia (type-locality, Brazil, Rio de Janeiro, Nova Friburgo). Ytu, gen. n.. type-species, Ytu zeus, sp. n. (type-locality, Brazil, São Paulo, Itu), including the following new species (their type-localities in parentheses): artemis (Brazil, Espírito Santo, Venda Nova), athena (Brazil, Paraná, MorretesJ, cupidus (Brazil, Rio de Janeiro, Teresópolis), demeter (Brazil, Rio de Janeiro, Teresópolis), hephaestus (Brazil, São Paulo, São Sebastião), morpheus (Brazil, Rio de Janeiro, Areal), and phebo (Brazil, São Paulo, Salesópolis). A larva from South Africa, described by Bertrand (1962) as belonging to Hydraenidae. is transferred to this family, and considered an undescribed genus, only referred to as genus B, because the original material was inaccessible, and only the larva is known. 2. Hydroscaphidae. Scaphydra, gen. n., type-species Hydroscapha hintoni Reichardt, 1911, is described for three Brazilian species of Hydroscaphidae recently described by the author.