Aspects of the Australasian zoogeography of the Macrophthalminae (Brachyura, Ocypodidae)

The Australasian species of Macrophthalmus show close zoogeographical relationships with those of ‘South-East Asia’, and to a lesser extent with those of ‘Japan’, relatively little relationships with those of the ‘Pacific’, very few with ‘Indian’ species and none with ‘African’ species. In terms of the coefficient of faunistic similarity used, the only region to show some degree of affinity with all other regions, is ‘South-East Asia’. This suggests the possibility that the genus Macrophthalmus arose in that region, and that the genus has radiated out from there to occupy its present wide distribution. A clear distinction is seen between the Australian distributions of the endemic and non-endemic Macrophthalminae. Endemic species are confined to the east of a line drawn through the Gulf of Carpentaria and Spencer Gulf, and show a marked preference for the temperate and subtropical regions within that zone. Non-endemic species, however, are mainly confined to the regions north of the Tropic of Capricorn, and occur in both the north-eastern and northwestern regions of Australia. Four boundary points have been noted on the east coast of Australia; Cooktown, Port Curtis, Moreton Bay and Sydney.