Monanema joopi n. sp. (Nematoda, Onchocercidae) from Acomys (Acomys) spinosissimus Peters, 1852 (Muridae) in South Africa, with comments on the filarial genus.

Monanema joopi n. sp. is described from blood drawn from the heart of the murid Acomys (Acomys) spinosissimus in South Africa. It is characterised by a non-bulbous cephalic extremity, shared with only one of its five congeners, and a cylindrical tail with caudal alae and a spicular ratio of 2.7 in the male. As is typical for the genus, microfilariae are skin-dwelling. They are 185 to 215 micrometres long and have no refractory granules beneath their sheath. A key to the species of Monanema is presented and an amended generic description, based on the six currently known species, is proposed. Species of Monanema are primarily lymphatic and the low intensity of infection with M. joopi n. sp. in blood from the heart, might suggest that not all adults settle in the heart cavities. One might also consider that other, more susceptible rodents serve as hosts for this parasite as well. To date, the geographic range of Monanema includes North America, Africa and Australia, each with representatives of a different lineage. Given the present hypotheses on the evolutionary origin and subsequent migrations of rodents, we expect the origin of Monanema to be in the Palearctic-Oriental region.