Origins of Australian arid-zone tenebrionid beetles

Abstract

Three biogeographic components with very different histories are represented among the tenebrionids of the Australian arid zone: the Indo-Malayan element, which is related mainly to the Indonesian fauna; the Austral Gondwanan element, mainly related to that of southern South America; and one here called Tethyan, related to the fauna of northern hemisphere arid regions. Indo-Malayan groups appear to have arrived comparatively recently, probably by invasion from the north, and are differentiated within the arid zone mainly to the species level. Austral groups are the most diverse and have radiated extensively to generic level from ancestors inhabiting sclerophyll forest, probably by vicariance, within the present arid zone. Tethyan groups are endemic in the arid zone at tribal level and have no forest-inhabiting relatives anywhere. They have often become myrmecophilous in Australia, and because of their distribution patterns in the northern hemisphere, partial occurrence in coastal dunes, and apparently basal phylogenetic positions are surmised to have descended by vicariance from inhabitants of the coastal sand dunes of the Tethys Sea, probably in the Jurassic before there was an arid zone in Australia.