The distribution of monogeneans of the genus Ligophorus on gills of the soiuy mullet Planiliza haematocheilus

Abstract

The distribution on the host gills of three monogenean species of Ligophorus Euzet et Suriano, 1977, parasitising soiuy mullet Planiliza haematocheilus (Temminck & Schlegel, 1845) in the Black and Azov seas was studied. Specimens of L. pilengas and L. llewellyni prefer to localize on the same gill sites, namely, I-III gill arches and their medial sectors. The third species, L. kaohsianghsieni , was distributed on the gills more crowdedly, with about 80% of its specimens being present on II gill arch, occurring on the medial and ventral sectors approximately equally. In general, most monogeneans were found on the largest in area and well-watered gill arches and sectors, as well as the anterior hemibranchies, however within these areas they preferred to attach to proximal half of filaments with less amount of water current. The presence of congeners on gills had no significant effect on the distribution of L. pilengas and L. llewellyni . Increasing infrapopulation number resulted in a more uniform distribution of monogeneans on gills; their proportion upsurges significantly on the faster growing anterior hemibranchs as fish size increased.