The Taxonomic Position of Hemidonax Mörch, 1871 with a Review of the Genus (Bivalvia: Cardiacea)

Abstract Hemidonax Morch is considered to be sufficiently distinct to justify the recognition of the group at family level (Hemidonacidae) within the Cardiacea. The first record of the genus is from the late Oligocene or early Miocene of Victoria, Australia, and its subsequent fossil history is traced. Five Recent species and one subspecies are recognised, 4 of which are endemic to Australia. One extinct Australian species (Donax dixoni Tate) is also recognised. A new Recent species from northern Australia (H. arafurensis nov.) is described.