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During a recent helminthological study on fishes from the Gambia River basins, Senegal, monogeneans assigned to Dactylogyrus and Dogielius (Dactylogyridae) were found on the gills of 3 species of Labeo (Cyprinidae): L. coubie, L. parvus, and L. senegalensis. The following 14 (3 new) species were recovered from Labeo coubie (n = 21): Dactylogyrus decaspirus, Dactylogyrus dembae n. sp., Dactylogyrus falcilocus, Dactylogyrus jaculus, Dactylogyrus leonis n. sp., Dactylogyrus oligospirophallus, Dactylogyrus retroversus, Dactylogyrus titus, Dactylogyrus yassensis n. sp., Dogielius anthocolpos, Dogielius clavipenis, Dogielius complicitus, Dogielius flagellatus, and Dogielius harpagatus. The re-examination of the type specimens of Dactylogyrus cyclocirrus Paperna, 1973 from Labeo cylindricus and L. victorianus revealed that the original description of this species was based on 2 different species. Consequently, Dactylogyrus cyclocirrus was redescribed and the lectotype was designated from the syntypes collected from Labeo cylindricus. Dactylogyrus cyclocirrus of Guégan et al. (1988) and D. cf. labeous Paperna, 1979 were found as senior subjective synonyms of D. yassensis and D. dembae n. spp., respectively. Host fishes of Labeo senegalensis (n = 15) were parasitized by the following 8 species: Dactylogyrus dembae n. sp., Dactylogyrus labeous, Dactylogyrus rastellus, Dactylogyrus senegalensis, Dactylogyrus tubarius, Dogielius anthocolpos, Dogielius flosculus, and Dogielius tropicus. Only 2 species were reported from Labeo parvus (n = 12): Dactylogyrus brevicirrus and Dactylogyrus dembae n.sp. Our detailed examination of haptoral structures with respect to the dorsoventral axis of the body showed that in Dactylogyrus spp. both anchors and their associated bar are located in the dorsal portion of the haptor, whereas these structures are ventrally located in species of Dogielius. This finding differs from many previously reported studies, in which the anchors and bar of Dogielius spp. are depicted as dorsal, and suggests the unnatural condition of the Dactylogyrinae.
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