First study on Gyrodactylus (Monogenea: Gyrodactylidae) in Morocco, with description of a new species on cyprinids (Actinopterygii: Cyprinidae)

Abstract

Monogenean flatworms are mainly parasitic in lower aquatic vertebrates including fish, anurans and chelonians. Gyrodactylus is one of the 23 genera of Gyrodactylidae, with 19 viviparous genera and four oviparous genera. With only 41 species described, the total number of Gyrodactylus species described from African freshwater fish still remains low. As a result, the known species represent only a fraction of the expected species richness of Gyrodactylus in Africa. Only three Gyrodactylus species have been described from small African cyprinids, all belonging to Enteromius, namely; G. ivindoensis Price & Gery 1968 from Enteromius cf. holotaenia in Gabon, G. kyogae from E. neumayeri and E. perince Paperna, 1973 in Uganda and G. paludinosus from E. paludinosus in South Africa. No single study has documented members of Gyrodactylus in Morocco. The current study focuses on parasites belonging to Gyrodactylus isolated from Luciobarbus pallaryi and Luciobarbus ksibi. A total of 738 cyprinid specimens were collected and examined for infection with Gyrodactylus. 26 Gyrodactylus individuals were isolated from these hosts. 12 were morphologically characterized, infecting Luciobarbus pallaryi having (11 parasite specimens) and Luciobarbus ksibi (a single parasite specimen). The low number of specimens of Gyrodactylus recorded may be an underestimation due to the fact that only the gills were examined. Morphological and morphometric observations suggest a species new to science. It differs from G. kyogae, G. ivindoensis and G. paludinosus by having a larger hamulus which has long roots, a larger ventral bar with anterolateral processes, and a male copulatory organ having one principal spine and six smaller spines. In view of the importance of the cyprinid-monogenean system in studying the aquatic biodiversity and biogeography of North Africa, the present study is a substantial contribution to the parasite species inventory of these fishes.