Similarities in the genitalia and reproductive behaviour of male and female Tholymis tillarga (Fabr.), Parazyxomma flavicans (Martin), Brachythemis lacustris Kirby and B. leucosticta (Burm.) (Anisoptera: Libellulidae)

The genera Tholymis Hagen and Parazyxomma Pinhey have been classified in the Trameinae (or Zyxommatinae), whereas Brachythemis Brauer is included in the Sympetrinae. In spite of this, however, the male secondary genitalia and the arrangement of the female’s sperm storage organs in T. tillarga, P. flavicans, B. lacustris and B. leucosticta resemble each other much more closely than they do those of any other sp. so far examined in either subfamily. Moreover these spp. show several other structural similarities as well as having comparable reproductive behaviour. The structural and behavioural similarities are unlikely to be the result of evolutionary convergence and probably result from a recent common ancestor. It may, therefore, be appropriate to include them within one subfamily.