First insights into the diversity of gill monogeneans of‘Gnathochromis’andLimnochromis(Teleostei, Cichlidae) in Burundi: do the parasites mirror host ecology and phylogenetic history?

Abstract

Monogenea is one of the most species-rich groups of parasitic flatworms worldwide, with many species described only recently, which is particularly true for African monogeneans. For example, Cichlidogyrus, a genus mostly occurring on African cichlids, comprises more than 100 nominal species. Twenty-two of these have been described from Lake Tanganyika, a famous biodiversity hotspot in which many vertebrate and invertebrate taxa, including monogeneans, underwent unique and spectacular radiations. Given their often high degrees of host specificity, parasitic monogeneans were also used as a potential tool to uncover host species relationships. This study presents the first investigation of the monogenean fauna occurring on the gills of endemic ‘Gnathochromis’ species along the Burundese coastline of Lake Tanganyika. We test whether their monogenean fauna reflects the different phylogenetic position and ecological niche of ‘Gnathochromis’ pfefferi and Gnathochromis permaxillaris. Worms collected from specimens of Limnochromis auritus, a cichlid belonging to the same cichlid tribe as G. permaxillaris, were used for comparison. Morphological as well as genetic characterisation was used for parasite identification. In total, all 73 Cichlidogyrus individuals collected from ‘G.’ pfefferi were identified as C. irenae. This is the only representative of Cichlidogyrus previously described from ‘G.’ pfefferi, its type host. Gnathochromis permaxillaris is infected by a species of Cichlidogyrus morphologically very similar to C. gillardinae. The monogenean species collected from L. auritus is considered as new for science, but sample size was insufficient for a formal description. Our results confirm previous suggestions that ‘G.’ pfefferi as a good disperser is infected by a single monogenean species across the entire Lake Tanganyika. Although G. permaxillaris and L. auritus are placed in the same tribe, Cichlidogyrus sp. occurring on G. permaxillaris is morphologically more similar to C. irenae from ‘G.’ pfefferi, than to the Cichlidogyrus species found on L. auritus. Various evolutionary processes, such as host-switching or duplication events, might underlie the pattern observed in this particular parasite-host system. Additional samples for the Cichlidogyrus species occuring on G. permaxillaris and L. auritus are needed to unravel their evolutionary history by means of (co-)phylogenetic analyses.

Structure of parasites community in Chaetobranchopsis orbicularis (Cichlidae), a host from the Amazon River system in northern Brazil

“…Moreover, they are important ornamental fish and are among the most important protein sources in many parts of the world, often including low-and middle-income countries (Kullander 1998;Vanhove et al 2016). Thus, cichlid species are an interesting group to study because of their rapid speciation, species richness, and high levels of endemism in some regions of the world (Kmentová et al 2016). However, the great majority of studies on Amazonian cichlid fish have been were conducted on Astronotus ocellatus (Azevedo et al 2007;Abdallah et al 2008;Neves et al 2013).…”

Reduced host-specificity in a parasite infecting non-littoral Lake Tanganyika cichlids evidenced by intraspecific morphological and genetic diversity

“…Currently, 13 monogenean genera are known to infect cichlid species and six of these have been observed on African representatives36. Cichlidogyrus (Monopisthocotylea, Dactylogyridae) is the most species rich, with 102 representatives recorded from 88 different host species10111213141518373839404142. This genus displays variation in host-specificity and contains generalist but also strictly specialist species3943.…”

Deep-water parasite diversity in Lake Tanganyika: description of two new monogenean species from benthopelagic cichlid fishes

“…Although the forked shape of the accessory piece of C. brunnensis n. sp. is similar to an undescribed species collected from Limnochromis auritus [ 50 ], a member of Lake Tanganyika’s benthic deep water cichlid tribe Limnochomini, differences in haptoral sclerotised structures, namely the length of the dorsal bar auricles (on average 11.1 μm in C. brunnensis vs c. 45 μm in the undescribed species) and the shape of the anchors allows clear distinction between them.…”

“…Indeed, this is suggested by the phenotypic similarity of C. brunnensis n. sp. to an undescribed species collected from the benthic cichlid Limnochromis auritus (Boulenger, 1901) [ 50 ] and its quite different morphology of sclerotised structures as compared to C. attenboroughi n. sp., which infects another deep-water cichlid species, Benthochromis horii .…”