Aspects of the morphology and life history of Oculotrema hippopotami (Polystomatidae: Monogenea)

[摘要] Being the only monogenean known from a warm-blooded animal and from a mammalOculotrema hippopotami Stunkard (1924) took a major leap in monogenean evolution.After its description in 1924 various researchers rejected the claim that it came from thehippopotamus and made it out as a mislabeled specimen. It was only 40 years later thatthis parasite received full recognition. In spite of the fact that it was described more thanseven decades ago, only a few papers on this parasite have seen the light. During 1996this parasite was rediscovered in South Africa. A hippopotamus culling program inKwazulu-Natal gave an opportunity to study this parasite.The present study is the first detailed attempt to study the morphology and life history ofOculotrema hippopotami. The approach in this study was as follows:1. Background on the host's morphology, behaviour and phylogeny is given. Thehippopotamus' eye is situated deep in the orbit with the result that a deep creviceis present all around the eye, which serves as habitat for the parasites.2. The external morphology of the egg, oncomiracidium and adult parasite wasstudied USIng scannmg electron rrucroscopy. This is the first ever scanrungelectron microscopical study of 0. hippopotami and this study revealed many newinformation.3. The internal morphology of the adult parasite was studied histologically usingwax sections. This revealed unique musculature in the mid piece that has neverbefore been reported for any polystomatid parasite.4. Sperm morphology and the ultrastructure of the musculature in the mid piece wasstudied at transmission electron mieroeope level. Indications are that the spermmorphology is very similar to that reported for other polystomatids.5. Infection levels for different seasons were compared. In contrast with most otherpolystomatids that reproduce during the warmer summer months, 0. hippopotamilays eggs during the cooler winter months.6. The parental care and behaviour of a pair of hippopotami with a newborn calfwere studied. A very close bond with long periods of physical contact wasobserved. This could give an ideal opportunity for parasite transmission frommother to calf.

[发布机构] University of the Free State