[The genus Onchocherca : hypothesis on its evolution and a key to the species (author's transl)]

Abstract

A phylogenetic tree and a dichotomic key to the species in the genus Onchocerca are proposed. The origin and principal evolution have taken place in Africa where the most primitive species (O. railieti in the donkey) and the greatest number of species (half of the 24 representatives of the genus) occur. This evolution apparently took place in a relatively recent geological period, corresponding perhaps to the establishment of the Equidae in Africa during the Pleistocene. The species in humans, O. volvulus, belongs to a small line of Onchocerca in Africa Bovidae of the Savanna which is morphologically highly evolved (musculature atrophied and hypodermis hypertrophied in the female, intranodular location). O. volvulus appears to be a parasite which is still not well adapted to man (microfilariae not well tolerated).