Integrative taxonomy of spp. (Monogenoidea: Dactylogyridae) parasites of characiform and gymnotiform fishes from the coastal drainages of the Eastern Amazon, Brazil.

Eight species (four new) of are reported from Characiformes and Gymnotiformes fishes of the coastal drainages of the Eastern Amazon. n. sp. is characterized by having a male copulatory organ (MCO) with three and a half counterclockwise rings, absence of vaginal sclerite, and a V-shaped ventral bar. n. sp. has MCO with two and a half counterclockwise rings, dumbbell-shaped accessory piece, similar anchors, open V-shaped ventral bar, and open U-shaped dorsal bar. n. sp. exhibits an elongate and robust body, MCO comprising one counterclockwise ring, similar anchors with wavy point, and dumbbell-shaped ventral and dorsal bars. n. sp. has MCO comprising two and a half counterclockwise rings, vaginal canal convoluted, point of the dorsal anchor with ornamentation as sclerotized shredded filaments, elongate dumbbell-shaped ventral bar, and U-shaped dorsal bar. and from (Characiformes) and the species, and , from (Gymnotiformes) are reported, and their molecular sequences are presented in this study. Phylogenetic analyses based on molecular data (28S rDNA and COI mtDNA) reveal that species of lacking vaginal sclerite are closely related to species that possess vaginal sclerite, suggesting that the absence of vaginal sclerite in may be the result of a secondary loss. The relationships between species of and other Neotropical dactylogyrids are also addressed.