Gill Monogeneans of African Tetra, Brycinus kingsleyae (Günther, 1896), From the Nyong River: Biotope, Distribution and Site Selection

Monogenea is a taxon containing flatworms that are primarily parasites of the skin and gills of fish. The African tetra, Brycinus kingsleyae (Günther, 1896), is a commercial fish species in artisanal fisheries in Southern Cameroon. Although the gill monogeneans of this fish species have been described, no ecological research has been carried out on this component community. The present study was conducted in the Nyong River to provide the first data about some factors that influence the structure of its infracommunities. In dry seasons, 70 fish specimens consisting of 27 males and 43 females of fork length between 9.5 and 14.1 cm were sampled.The analysis of their gill filament number indicated that the gill system of B. kingsleyae is heterogeneous because this factor varies with the length of the fish and depends on the gill arch. The studied guild consisted only of core species: Annulotrema combesi Birgi, 1988, Annulotrema maillardi Birgi, 1988, Annulotrema nyongensis Birgi, 1988, Annulotrema bouixi Birgi, 1988, and Characidotrema regia Birgi, 1988. The number of gill filaments and the parasitic load increased with the fish length, indicating that larger hosts provide a greater diversity of niches for parasites. Monogenean species exhibit various occupation patterns of gill arches, sectors, zones and gender differences in parasitological indices. This study reveals that the host length and sex, filament number, gill arch, sector and zone are largely responsible for structuring the studied component community.