Australian Marsh Beetles (Coleoptera: Scirtidae). 9. The relations of Australasian Ypsiloncyphon species to their Asian congeners, additions, mainly to Petrocyphon and Prionocyphon, and a key to Australian genera of Scirtinae.

The endemic Australasian species of Ypsiloncyphon are the sister group of the combined Asian species groups 1, 2, and 4. The description of the type species, Y. chlorizans (Klausnitzer), is supplemented by details of male and female genitalia. New species are described and illustrated in several genera: Austrocyphon scissus n. sp., Leptocyphon abnormis n. sp., Petrocyphon bonang n. sp., P. lacteus n. sp., P. televisionarius n. sp., Prionocyphon bidentatus n. sp., P. cacatua n. sp., P. laurae n. sp., P. neboissi n. sp., P. serratus n. sp., P. uncatus n. sp., and P. urbanus n. sp. Genus Prionocyphon is distinguished from Oriental genera with similar antennal modifications. However, a synapomorphy of Prionocyphon as presently understood is not known. Supplementary information on various species in the aforementioned genera and in Pachycyphon and Calvarium is provided. A key to the genera of adult Australian Scirtidae: Scirtinae is presented.