The oribatid mite genus Topalia in Australia (Oribatida: Nosybeidae) and the taxonomic status of related families and genera.

Five new species of Topalia (Nosybeidae) are described from Australia: Topalia caliginosa sp. nov. from Victoria, T. corinnensis sp. nov. from Tasmania, T. dunlopi sp. nov. and T. katyae sp. nov. from Norfolk Island and T. royi sp. nov. from New South Wales. The genus was known previously from Australia from unidentified specimens only. I revise the generic definition, provide a key to species and clarify the family placement and taxonomic status of Topalia, Nosybea, Lamellocepheus and Charassobates. From a phylogenetic analysis and identification of synapomorphies, I consider Topalia, Nosybea and Lamellocepheus are valid, morphologically related and included in the Nosybeidae. The superfamily Charassobatoidea is valid, and contains Charassobatidae, Nosybeidae and Microtegeidae. These families have synapomorphies of a narrow, elongate subcapitulum, minute notogastral setae with at least one pair in the d series retained in the adults (dm in Nosybeidae, dp or dm in Microtegeidae, full complement in Charassobates). Immatures of Nosybeidae and Microtegeidae are undescribed, but in Charassobates are eupheredermous, plicate, and the tritonymph has the full complement of setae in the d series. Charassobates and Topalia have the synapomorphy of a ventral plate tectum, providing strong evidence for their relatedness. By way of contrast, the Cepheoidea, in which Nosybeidae and Microtegeidae have been placed by various authors, have a broad subcapitulum, well-developed setiform notogastral setae positioned marginally and lacking the d series, and no ventral plate tectum. The immatures are eupheredermous but non-plicate and the tritonymph lacks setae in the d series. Based on these differences, Nosybeidae, Microtegeidae and Charassobatidae cannot be included in the Cepheoidea.