Aspekte van die biologie van die visektoparasiet Dolops ranarum (Stuhlmann, 1891) (Crustacea: Branchiura)

Ph.D. (Zoology)D. ranarum was sampled from the Limpopo River System. It was studied morphologically by means of light microscopy of whole mounts and scanning electron microscopy. The histology of this organism was also studied. As this parasite was described in 1891, a comprehensive description of the species was done by means of scanning electron microscopy. Graphic reconstructions of the genital systems were done in order to verify and elucidate its morphology. Various areas of said systems were histologically characterised and deductions made concerning the functions of the various cell-types and structures. Two glands, i.e. a digestive- and a spermatophoric gland were identified and described from the carapace of the male. Eggs sampled in the laboratory were studied with reference to hatching times and larvae were described morphologically. It was found from the aforegoing that larvae are parasitic directly after hatching. A histological study of host-damage by the parasite was done and it was found that infestation by ranarum causes loss of epithelial tissue, oedema and haemorrhage. The shape of the lesions were correlated with the shape and orientation of the adhesive appendages of the parasite. As significant confusion exists concerning the terminology used in the study of this group of animals, a list of such terms was compiled in order to delineate this. The role of environmental temperature as a factor influencing the limited geographical distribution of D. ranarum in Africa is discussed and the theory of continental drift is proposed as a possible explanation for the global distribution of this group