Australlus, a new genus for Gallinula disneyi (aves: Rallidae) and a description of a new species from oligo-miocene deposits at Riversleigh, northwestern Queensland, Australia

Gallinula disneyi Boles, 2005, was based on Late Oligocene-Middle Miocene (c. 25–15 Ma) fossils from Riversleigh World Heritage Property in Boodjamulla (Lawn Hill) National Park, northwestern Queensland, Australia. If the generic assignment is correct, this species would be the earliest known crown group representative of Rallidae. We have therefore reassessed the phylogenetic relationships of this rail using both the original and newly recovered material. It is found to be a relatively basal rallid with some affinity to Porphyrio, and the new genus Australlus is erected for this taxon. A second species in the genus is described from Middle Miocene sites at Riversleigh World Heritage Property. A third rallid, smaller than either species of Australlus, is indicated by a mandible fragment, also from Riversleigh, but is not named. These rails are the only gruiforms known from Riversleigh and, with a single species of stork, are the only small non-passerine ground-birds known from these faunas.Trevor H. Worthy and Walter E. Bole