Abstract

A new genus of octopus is described from northern Australian waters. Ameloctopus litoralis, gen. et sp. nov., is a shallow-water octopus characterised by the absence of an ink sac, vestigial funnel organ, terminal organ without a diverticulum, marked elongation of the arms and arm autotomy. It is found across northern Australia from southern Queensland to north-west Western Australia, primarily on coastal mudflats and intertidal reefs. This species occupies lairs in shallow and intertidal coastal habitats, feeding by extending arms from the safety of the lair or by foraging at night during low tides, over open sand, mud and rubble. A. litoralis lays large eggs, indicating that hatchlings are benthic and dispersal limited. Loss of the ink sac in a shallow-water octopod and the development of arm autotomy are discussed. Relationships with other octopod taxa exhibiting similar traits are examined.