Australian Hydraena (Coleoptera : Hydraenidae)

The taxonomy of Australian Hydraena is revised with all currently available material, including types of all previously named species. The 29 species now known from Australia are all described and their distinctive characters illustrated. H. blackburni Zaitzeff (= H. evanescens Blackburn, not Rey), H. castanea Deane, H. luridipennis Macleay (= H. acutipennis Fairmaire = H. torrensi Blackburn = H. selecta Deane = H. plenipennis Deane; new synonymies), H. rudallensis Blackburn, H. simplicicollis Blackburn and H. williarnsensis Deane are redescribed from types. The following new species are named: H. ambifagellata, H. australica, H. barbipes, H. billi, H. brittoni, H. clavigera, H. cygnus, H. decipiens, H. extorris, H. hamifera, H. hynesi, H. impercepta, H. lucernae, H. magnetica, H. parva, H. pilipes, H. reticulata, H. robusta, H. ruinosa, H. simplipes, H. traprzoidalis, H. tricantha, and H. ypsilon. Formally, the Australian species all fall into subgenus Hydraena, ss., the monophyly of which is, however, as yet unconfirmed. Brief remarks about habitats and habits of Australian Hyrdaena and of other hydraenid genera in Australia are presented.