Studies on the parasites of zebras. V. Nematodes of the Burchell's and Hartmann's mountain zebras from the Etosha National Park, South West Africa/Namibia.

Nine Burchell's and 6 Hartman's mountain zebras were culled during the 3 climatic periods characteristic of the Etosha National Park, South West Africa/Namibia, and were examined for helminths. The Burchell's zebras ranged in age from 4 1/2 to 19 years and the mountain zebras from 3 1/2 to 13 years. Twenty-five species of nematodes, belonging to the families Atractidae, Strongylidae, Oxyuridae, Onchocercidae and Habronematidae, were recovered. Of the family Cyathostominae, the following species were the most numerous in the Burchell's zebras: Cyathostomum montgomeryi (7 120-67 042), Cylicocyclus triramosus (11-34 540), Cylicostephanus minutus (4 698-40 019) and Cylindropharynx sp. (? intermedia) (3 591-40 018). The atractids present were: Crossocephalus viviparus (20-5 045 212) and Probstmayria vivipara (5 140-3 801 300). Three of the above cyathostome species were also most abundant in mountain zebras: Cylicocyclus triramosus (54-19 782), Cylicostephanus minutus (555-12 396) and Cylindrophrynx sp. (? intermedia) (3-5 325). New reports include Cylicostephanus longiconus in the Burchell's zebras and Cyathostomum alveatum, Cyathostomum montgomeryi, Cylicostephanus bidentatus and Draschia megastoma in the mountain zebra. The overwintering of 4th stage cyathostomes in the gut walls and their emergence which differ in the 2 hosts, are discussed.