Branchial monogenean parasites (Monogenea: Dactylogyridae) of fishes from the Okavango River and Delta, Botswana

[摘要] English: The Okavango Delta has received much popularity for the host of wildlife that it sustains. Morerecently it has gained increasing interest for the rich diversity of fish species that occur there.The fishes of the Okavango are also becoming increasingly important as a natural resourceattracting revenue to Botswana in the forms of ecotourism and aquaculture and also as animportant food source for the local community.The Okavango Delta is a flood driven system and much of the fish distributionthroughout the Delta and the timing of certain behavioural activities are dependent on the timingand magnitude of the flood. For the purpose of determining the distribution of fish parasitesthroughout the system, the distribution of the fish hosts was determined and it was found thatfish community structure could be used to distinguish different habitat types within the differentecological regions.Fifty-nine of the expected 68 fish species for the Delta have been collected. Thesespecies represent 12 families of which the families Cichlidae and the Cyprinidae are the mostabundant, making up about 50 percent of the species collectively. Various parasites have beencollected from these fishes of which the monogeneans seem to be the most prevalent andabundant and currently represent approximately 36% of the parasites collected. Most of themonogeneans recorded thus far were representatives of the subclass Polyonchoinea. Of these, allbelonged to the families Dactylogyridae and Gyrodactylidae.Of the monogenean parasites infesting the Okavango fishes, the representatives of thefamily Dactylogyridae were the most diverse. Genera of African dactylogyrids are eitherendemic to Africa or belong to genera with wider geographical ranges. In general dactylogyridsare host specific and their zoo geographical affinities are therefore linked to the faunistic origin oftheir hosts. The distribution of dactylogyrid species within Africa is determined by thedistribution pattern of their hosts.Twenty-two dactylogyrid species comprising seven genera were recorded, of these 10species were previously undescribed. This study represents the first records of representatives ofthe class Monogenea from Botswana and hence the Okavango Delta.

[发布机构] University of the Free State