Transantarctic relations of Diachlorini (Diptera: Tabanidae)

Diachlorini are distributed in 8 vegetation zones, but it is only in Neotropis that they occupy the entire environmental range. Plesiomorphic, intermediate and apomorphic character states in Diachlorini were discussed. The definition of ancestral forms is based on plesiomorphic character states. Their occurrence in Australia is indicated by intermediate character states in east Australia and New Caledonia. A four-step similarity analysis resulted in two clusters of closely related plesiomorphic taxa, one including Cydistomyia TAYL. and Nubiloides COSC.& PHIL., and the other with Cydistomorpha TROJ. as the basis for all other clusters, but nearest to Neotropical Stenotabanus LUTZ-related taxa. Similarity analysis confirmed the hypothesis of much closer morphological relations between South American and Australian taxa, than between Australian and South African ones. Transantarctic hypothesis is confirmed.