Intraspecific morphological variation in Cichlidogyrus (Monogenea) parasitizing two cichlid hosts from Lake Tanganyika exhibiting different dispersal capacities

Abstract

As parasites depend on their hosts and play a significant role in their ecology and evolution, we hypothesized an association between the host dispersal capacity and the intraspecific variability of their host-specific parasites. We investigated the morphological variability of the gill monogeneans Cichlidogyrus gistelincki and C. milangelnari parasitizing the Tanganyika cichlids ‘Ctenochromis’ horei and Cyprichromis microlepidotus, respectively. The profound ecological and behavioural differences between these host species allowed us to assume that the former is a good and the latter a poor disperser. Specimens of monogeneans were collected from cichlids inhabiting different locations at the northern end of Lake Tanganyika. Sequences of the 28S rDNA gene were used to confirm parasite conspecificity. Dorsal and ventral anchors of the attachment organ of parasite specimens were used to evaluate variability in shape. Geomorphometric analyses revealed that populations of C. milangelnari, which parasitize poorly dispersing cichlids, are more differentiated than populations of C. gistelincki infecting well-dispersing hosts. Both anchors showed significant shape variation between populations of C. milangelnari. In C. gistelincki, anchors were highly similar in comparisons of populations from nearby and from distant locations.