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The order Characiformes is one of the largest and most diverse components of the Neotropical and African ichthyofaunas. African freshwaters harbour more than 200 characiform species currently arrayed in four families: Alestidae (118 species), Citharinidae (8 species), Distichodontidae (101 species), and Hepsetidae (5 species). Alestidae, often called African tetras, are known to be parasitized by monogenean platyhelminths representing three genera: Annulotrema (39 species), Characidotrema (10 species), and Afrocleidodiscus (1 species). During field trips (2007 – 2015) we sampled 11 species of African tetras (Alestes baremoze, A. dentex, Arnoldichthys spilopterus, Brycinus imberi, B. leuciscus, B. nurse, Hydrocynus forskahlii, H. brevis, H. vittatus, Micralestes accutidens, M. elongatus), and revealed the presence of monogeneans belonging to three genera within the Dactylogyridae: Annulotrema (19 species), Characidotrema (5 species), and Afrocleidodiscus (1 species). In 2016, I continue to work towards my Ph.D. goals that are as follows: (A) to investigate species diversity of dactylogyrids of African tetras from seven African countries (Democratic Republic of the Congo, Kenya, Nigeria, Senegal, South Africa, Sudan, and Zimbabwe [1]); (B) to evaluate the relative taxonomic importance of the characters of the reproductive organs and those of the haptoral sclerites in accordance with molecular data [2]; and (C) to investigate the relationships between dactylogyrid species from African tetras based on nuclear ribosomal DNA gene sequences. Preliminary phylogenetic analyses confirmed the monophyly of Characidotrema species [3]. Species of Afrocleidodiscus hydrocynuous and representatives of Annulotrema clustered together, while Afrocleidodiscus sp. 1 from Distichodus rostratus (Characiformes: Distichodontidae) forms separate cluster close to the Characidotrema spp. Division of both Afrocleidodiscus species highlights the necessity of revision this genus.
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