Kindred spirits: 'Brachythemis leucosticta',Africa's most familiar dragonfly, consists of two species(Odonata: Libellulidae)

摘要

Brachythemis leucosticta was found to include two morphotypes, which we con-sider to represent separate species. Males are separable by the ventral structure of S8and often differ in the colour of the venation and genital lobe. Females are as yet notreliably distinguishable. Examination of 1,154 males demonstrated that both speciesare widespread: the true B. leucosticta occupies most of tropical Africa and Mada-gascar, while B. impartita (comb. nov.; corrected spelling — neotype ♂: Ngaoun-daba Ranch, Cameroon; in RMNH) ranges north and south of the Sahara, andextends into Eurasia. The two overlap from The Gambia to Ethiopia and south atleast to Lake Victoria. The presence of wing bands was scored for all examined malesand 970 females. Banded females are frequent in sub-Saharan populations of B. im-partita, but virtually absent in B. leucosticta and northern B. impartita. B. impartitamales become banded shortly after emergence, but B. leucosticta becomes so moregradually. Larval morphology and ecology require further study, but some ecologi-cal and seasonal segregation may occur in areas of overlap. Of two larval forms de-scribed from Uganda, the 'mud form' may pertain to B. leucosticta, and the 'sandform' to B. impartita.