This study is aimed at solving the long-standing ambiguity about the phylogenetic placement of the Australian ground-beetle genus Tasmanitachoides. A recently published phylogeny of the supertribe Trechitae using morphological characters of larvae is re-examined in light of new discoveries. The results of the phylogenetic analysis of 65 informative characters for 36 taxa reject the previously maintained opinion of affinities between Tasmanitachoides and Tachyini. Instead it is hypothesised that the genus is a member of the monophyletic tribe Trechini and most likely belongs to the Trechodina radiation, represented in the analysis by the genera Perileptus and Thalassophilus. Older-instar larvae of Tasmanitachoides, Kenodactylus and Mioptachys, as well as the first-instar larva of Pachydesus, are described. An updated identification key to all analysed Trechitae genera is provided.