Australian pinnotherid crabs: a new species and new records of Arcotheres Manning, 1993 (Brachyura, Pinnotheridae)

Abstract Prior to the present study, 11 genera and 16 species of pinnotherid crabs were known from Australia, of which two species of the genus Arcotheres were recorded: Arcotheres boninensis and A. similis . The current study extends our knowledge of Australian Arcotheres in a species new to science, significant range extensions for A. boninensis in Australia, and the first national record of A. exiguus . The new species ( A. eclecticus ) is closest to Arcotheres palaensis , but differs chiefly in features of the carapace. Arcotheres boninensis was formerly known from Western Australia and is now known to span all of northern Australia. To date, A. exiguus has been recorded from the Philippines westwards to Singapore, Malaysia and India; first records from Australia and Hong Kong represent the southern- and northernmost records of the species, respectively. The Australian pinnotherid fauna now stands at 11 genera and 18 species, of which four species belong to Arcotheres . A key to the Australian species of Arcotheres is provided.