New species of Aphanoblastella (Monopisthocotyla, Dactylogyridae) parasitizing Pimelodella cf. cristata (Siluriformes: Heptapteridae) from the Eastern Amazon, Brazil, with molecular phylogenetic insights

Four new species of Aphanoblastella are described from the gills of Pimelodella cf. cristata (Siluriformes: Heptapteridae) from the coastal drainages of the Eastern Amazon, Brazil. Aphanoblastella ophiurophallus n. sp. differs from its congeners mainly by its sigmoid male copulatory organ with an acutely tapered distal portion, elliptical germarium, heavily sclerotized vaginal atrium, and dorsal bar with a posteromedial process. In contrast, Aphanoblastella mandi n. sp. has a male copulatory organ with 1½ counterclockwise rings, a campanulate vaginal vestibule, anchors with truncated superficial roots, a ventral bar curved posteriorly with truncated ends, and hooks with broadly truncated thumbs. Aphanoblastella tembetenetehara n. sp. is set apart by its male copulatory organ with 2½ counterclockwise rings, an accessory piece with a hook-shaped tip, a non-marginal vaginal aperture, a dorsal V-shaped bar with a distinct medial constriction, and hooks with a small proximal dilation and a flattened thumb. Aphanoblastella falcatus n. sp. can be recognized by a ventral anchor with an inconspicuous superficial root, a dorsal anchor with a small perforation at the base, a male copulatory organ with 3-4 rings, an accessory piece with two dorsal, ear-like projections at its distal portion, and hooks with a very short, depressed thumb. Molecular phylogenetic analysis based on partial 28S rDNA indicates that Aphanoblastella mandi n. sp. and Aphanoblastella tembetenetehara n. sp. form a monophyletic group nested among previously described congeneric species. This study provides the first record of Monopisthocotyla from Pimelodella cf. cristata.