The Streptaxoidea are an ancient and species diverse group that is poorly understood. Examination of the reproductive anatomy of Diaphera showed it to be notably distinct from that of most other streptaxid genera but to exhibit similarities with the reproductive anatomy of Sinoennea (Enneinae), Careoradula (Strepaxinae), Discartemon (Strepaxinae), Augustula (Strepaxinae), and a species of Imperturbatia (Gibbinae). Our molecular phylogenetic analysis placed the two genera with high-spired shells, Sinoennea and Diaphera, in an isolated position as a sister group to the Streptaxidae sensu stricto. This basal divergence within the Streptaxoidea provides support to the proposed recognition of a new family, the Diapheridae. None of the genera possessing low-spired shells, Careoradula, Discartemon, Augustula, and Imperturbatia, were available for inclusion in the molecular analysis and we therefore provisionally restrict the Diapheridae to Diaphera and Sinoennea. However, based on their reproductive anatomy Careoradula, Discartemon, Augustula and a species of Imperturbatia may cluster with the Diapheridae when included in a molecular analysis.
© 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160, 1–16.