Population dynamics and spatial distribution of monogeneans on the gills of Oreochromis mossambicus (Peters, 1852) from two lakes of the Limpopo River System, South Africa.

An investigation was conducted into the parasitic infection of an indigenous cichlid, Oreochromis mossambicus, collected seasonally from the Nwanedi-Luphephe dams of the Limpopo River System from July 2007 to April 2009. Of 157 host specimens examined, 115 (73.25%) were infected by at least one gill parasite. In all, 1565 monogenean specimens were collected, belonging to five different species and two genera: Cichlidogyrus (C. halli, C. sclerosus, C. tilapiae and C. dossoui) and Scutogyrus (S. longicornis). Infracommunities were poor, with only 27 (17.20%) hosts harbouring four of the five species observed. Cichlidogyrus halli was the dominant species, with a prevalence of 73.25%. Prevalence values for each of the other four species were less than 50%. The mean intensities for each of the five species were low ( < 8 parasites/host). The parasite abundance and intensity levels were not influenced by either the sex or the size of the host. The abundance of all parasite species except for S. longicornis exhibited seasonal fluctuations, reaching peaks in winter and summer. The spatial distribution of each parasite was studied on different regions of the gill, and positive associations among some species were revealed.

Report on some monogenean and clinostomid infestations of freshwater fish and waterbird hosts in Middle Letaba Dam, Limpopo Province, South Africa.

This report deals with the results of a parasitological study done as part of a post-impoundment ecological study of Middle Letaba Dam, Limpopo Province, South Africa. It involved a seasonal survey protocol with particular attention to the diversity and prevalence of the parasitic fauna of the indigenous fish community of the dam and the role of selected fish-eating birds in the life cycle and distribution of fish helminths. The potential species composition of fish of the dam is provided. Monogenean and clinostomatid parasites encountered are listed and infestation statistics of fish and fish-eating bird hosts are presented. The results of this study also provide information on new distribution and host records of the encountered monogeneans.

Observations on a lesser-known monogenean, Udonella myliobati, from a copepod parasite, Lepeophtheirus natalensis, parasitizing the spotted ragged-tooth shark, Carcharias taurus, from South African waters.

The phylogeny of the genus Udonella has been disputed for quite some time, but recent phylogenetic analysis of molecular data confirms that the genus is a monopisthocotylean monogenean. Specimens of Udonella myliobati parasitizing the copepod Lepeophtheirus natalensis, an ectoparasite of the spotted ragged-tooth shark, (Carcharias taurus), were collected and studied. A total of 771 monogenean specimens were recovered from 54 infected copepods examined, with a mean intensity of 14,3 worms per copepod. Most of the monogeneans were found attached to the dorsal surface of the lateral and frontal marginal membranes of the copepod carapace. Eggs, with filaments and adhesive discs, were found ventrally on the host, mainly attached to the maxillae and maxillipeds, in clusters of 12-14. Observations on the morphology, distribution and behaviour of this monogenean are presented with the aid of light and scanning electron microscopy.

Description of the previously unknown male of Argulus kosus Avenant-Oldewage, 1994 (Crustacea : Branchiura).

Argulus kosus Avenant-Oldewage, 1994 was described from two females collected in Kosi Bay, South Africa. Individuals of both sexes have now been found associated with freshwater, estuarine and marine fishes in Lake St Lucia on the coast of northern KwaZulu/Natal. The male is described, and A. smalei Avenant-Oldewage & Oldewage, 1995 is synonymised with A. kosus.