Hybridization between the megasubspecies cailliautii and permista of the Green-backed Woodpecker, Campethera cailliautii
Prigogine, A. 1987. Hybridization between the megasubspecies cailliautii and permista of the Green-backed Woodpecker, Campethera cailliautii. Le Gerfaut, 77: 187–204.
The two taxa permista and cailliautii, belonging to the genus Campethera, have been considered first as distinct species, but later as subspecies. In fact they are in contact in a zone which starts from the region northwest of Lake Tanganyika, crosses Shaba and Kasai, and reaches Angola. A detailed study of all museum specimens collected in or near this zone has been achieved; permista and cailliautii are morphologically different, but they interbreed freely in a zone that corresponds to a zone of allopatric hybridization. This hybridization, occurring on a large scale, demonstrates that these two taxa are conspecific. They are ecologically separated: permista is confined to equatorial forest, whereas cailliautii prefers more-open habitats. The hybrid zone corresponds to an ecotone.
An hypothesis is discussed to explain the evolutionary history of the paraspecies Campethera maculosa and C. cailliautii (including permista and kaffensis).