Phylogenetic analysis of Staphyliniformia (Coleoptera) based on characters of larvae and adults

One hundred and twenty-one morphological characters of larvae and adults of the series Staphyliniformia were scored (multistate coding) and analysed to determine the family group relationships of the polyphagan groups Scarabaeoidea, Histeroidea, Hydrophiloidea and Staphylinoidea. Cladograms were rooted with exemplars of Adephaga, Archostemata, Myxophaga and the polyphagan families Dascillidae, Derodontidae, Eucinetidae and Scirtidae. Analyses of the same dataset with multistate characters re-coded as presence/absence (144 characters) produced cladograms that were similar to those produced from analyses of the original characters. Cladograms produced from partitioned larval and adult characters differed strongly, with adult-only trees more similar to those produced by combined data. The results confirm the monophyly of Hydrophiloidea + Histeroidea and of Staphylinoidea (including Hydraenidae). The Epimetopidae + Georissidae are the only strongly supported clade within Hydrophiloidea. A clade comprising Hydrochidae, Spercheidae and Hydrophilidae, and a sister-group relationship between the latter two families were confirmed in analyses of the data with presence/absence coding. Helophoridae, Epimetopidae and Georissidae are probably not a monophyletic unit, and additional evidence is needed for a reliable placement of Helophoridae. Scarabaeoidea are placed as a sister taxon of Hydrophiloidea + Histeroidea, but support for this relationship is weak. The branching pattern ((Hydraenidae + Ptiliidae) + (Leiodidae + Agyrtidae)), and a clade comprising Scydmaenidae, Silphidae and Staphylinidae (= 'staphylinid group') are well founded. The branching pattern (Orchymontiinae + (Prosthetopinae + (Ochthebiinae + Hydraeninae))) within Hydraenidae is confirmed. Poor resolution at the base of the trees and the placement of some nonstaphyliniform taxa (Dascillidae, Derodontidae, Scirtidae and Eucinetidae) as a sister group to a clade comprising Scarabaeoidea, Hydrophiloidea and Histeroidea suggests that Staphyliniformia may be paraphyletic. It is recommended that series names are eliminated from the classification of Polyphaga, at least for the more 'primitive' groups.