141 INTRODUCTION Although originally described from the Northern Hemisphere, Brundin (1966) clearly showed that the subfamily Podonominae had a higher diver- sity in the Southern Hemisphere, consistent with a Gondwanan origin. He considered the genus A rchaeochlus Brundin, 1966, to be the most plesio- morphic podonomine, with A frochlus Freeman, 1964, its probable sister-group. The plesiomorphic status of A rchaeochlus was confirmed when adults from Western Australia were found to possess biting mouthparts (Cranston et al. 1987; Downes & Colless 1967). The presence of apparently con- generic species in Australia strengthened the case for A rchaeochlus being of Gondwanan origin. Since Africa had separated from Antarctica and Australia by 120 mya, the African and Australian species are assumed to have been isolated from each other for at least this length of time (Cranston et al . 1987). E dward (1989) used enzyme electrophore- sis to show that there was little genetic similarity between African and Australian species, consist- ent with a long period of isolation. The larvae of this group live in the episodic streams associated with rock outcrops (Figure 1), with the exception of one A rchaeochlus species from Na- mibia (Cranston et al . 2002). Suitable habitats are, therefore, disjunct in occurrence, raising questions as to how the species have achieved their present distributions, as the adults appear disinclined to fly great distances (Martin et al . 2002). Martin et al . (2002) used molecular data to investigate the Phylogenetic relationships of Archaeochlus Brundin, Austrochlus Cranston and Afrochlus Freeman (Diptera: Chironomidae), basal genera with a Gondwanan connection Jon Martin 1 , Victor Guryev 2* , Samuel S. Macdonald 1 , Alexander Blinov 2 & Donald H.D. E dward 3 1 Genetics Department, University of Melbourne, Victoria 3010, Australia; e-mail: j.martin@ unimelb.edu.au; s.macdonald@ pgrad.unimelb.edu.au 2 Laboratory for Molecular Biology, Institute of Cytology & Genetics, Novosibirsk 630090, Russia; e-mail: blinov@ bionet.nsc.ru 3 Department of Zoology, The University of Western Australia, Nedlands WA 6907, Australia; e-mail: dhedward@ cyllene.uwa.edu.au * Present address: Hubrecht Laboratory, Uppsalalaan 8, 3584CT Utrecht, The Netherlands; e-mail: guryev@ niob.knaw.nl In this paper the phylogenetic relationships among the podonomine genera A rchaeochlus Brundin, A ustrochlus Cranston and A frochlus Freeman are re-examined using DNA sequence data from two mitochondrial (mt) genes, Cytochrome b and Cytochrome oxidase subunit II, and the nuclear 18S ribosomal RNA gene. The results confirm that the African species of A rchaeochlus and the Aus- tralian A ustrochlus species are not monophyletic. A frochlus is, however, monophyletic within A rchaeochlus and there is some doubt as to whether generic separation is justified. Although A frochlus is a monotypic genus, larvae of two species, form A and form B, were present in the studied sample from the type locality . These two species appear differentiated in their mt se- quences, although more closely related on the basis of their 18S sequences. Form A appears more closely related to the species of A rchaeochlus than to form B. Some of the African A rchaeochlus species show a similar amount of sequence divergence to the populations of the Australian species. They appear to have diverged only within the last 10 my, while the Australian species are at least 18 my in age. _________________________________________________________________________ Proceedings of the workshop ‘African Diptera Biogeography & Gondwanaland’, 5 th International Congress of Dipterology, Brisbane, Australia, 29 Sept. – 4 Oct. 2002. Cimbebasia 19: 141-151, 2003