Monogenoidean parasites of the nasal cavities of Bryconops melanurus (Characiformes: Iguanodectidae) of the coastal drainages of the Eastern Amazon, Brazil: Proposal of Guamacotyle forficata n. gen. n. sp. (Polyonchoinea: Dactylogyridae)

Abstract

Abstract Two new species of Monogenoidea (Telethecium tiquira n. sp. and Guamacotyle forficata n. gen. n. sp.) from the nasal cavities of Bryconops melanurus (Bloch) are described from the Brazilian Eastern Amazon. Telethecium tiquira n. sp. is characterized by possessing a male copulatory organ (MCO) with two circular sclerotized brims on the base, a coiled tubular shaft having 1 ½ counterclockwise rings; an accessory piece with enlarged base, pincer-shaped at the distal portion; asclerotized calyx-shaped vaginal vestibule; and hooks with proximal shank dilatation comprising 3/4 of the shank length. The new species also differs from the congeners by lacking the protruding bag located at level of the terminal male genitalia.The monotypic Guamacotyle n. gen. is characterized by having a MCO with counterclockwise rings; an accessory piece non articulated to MCO, clamp-shaped; a sclerotized vagina with sinistrolateral aperture; ventral anchors larger than dorsal anchors; and hooks with similar sizes. The proposal of the new genus is also supported by phylogenetic analysis based on 28S rDNA, which supports the close relationship of Guamacotyle n. gen. with Cacatuocotyle papilionis and Diaphorocleidus spp., all parasites of Neotropical fishes.