Urocleidoides spp. (Monogenea: Dactylogyridae) from the gills of Parodon nasus (Characiformes: Parodontidae) from a Brazilian stream with descriptions of two new species

Abstract

Urocleidoides spp. are reported from the gills of 20 specimens of Parodon nasus (standard length 8.5–12 cm), from the Indiana stream, Tietê River, Upper Paraná River basin, municipality of Botucatu, São Paulo State, Brazil. Urocleoidoides tenuis and two new species were found. Urocleidoides indianensis n. sp. differs from its congeners mainly by the morphology of the vaginal sclerite that is robust, sickle-shaped, and forked at the distal end; and by the bulbous-shaped accessory piece of the male copulatory complex. Urocleidoides parodoni n. sp. resembles U. tenuis by presenting male copulatory organ with approximately 7 ½ counterclockwise rings, but differs by the morphology of the accessory piece (lobate with a small hook-like projection versus pincer-shaped), vaginal sclerite (thumb-like subterminal projection vs. presence of a distal hook), vaginal tube (conspicuously sclerotized vs. slightly sclerotized), shape of the ventral bar (bowed vs. wide V-shaped), ventral and dorsal anchors (robust base and short shaft vs. considerably less robust base and long shaft), and hooks (slender shank with a weakly sclerotized subunit at base vs. dilated shank). Sequences of the partial 28S rDNA gene of the dactylogyrids found in this study are provided. Phylogenetic analyses showed Urocledoides spp. from Parodontidae clustering together with strong support values. This study increases the number of valid Urocleidoides species to 39, and the number of species described from parodontid hosts to four.

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

“…These authors suggested that future investigation should focus on molecular characterization of stricto sensu and incertae sedis species to test the monophyly of Urocleidoides. The study of Oliveira et al (2021), also based on 28S rDNA analysis, supported the close relationship among some species of Urocleidoides and Cacatuocotyle papilionis Zago et al , 2018, suggesting that Urocleidoides may represent a non-monophyletic group.…”

“…The clade formed by the species of Urocleidoides showed significant support for both analyses (BI, P = 1 and ML, B = 82). One group consists of the species that parasitize anostomids ( U. paradoxus Kritsky, Thatcher & Boeger, 1986, U. sinus Zago et al , 2020 and U. digitabulum Zago et al , 2020) (BI, P = 1 and ML, B =100), parondontids ( Urocleidoides tenuis Zago et al , 2020; U. indianensis Oliveira et al , 2021 and U. parodoni Oliveira et al , 2021) (BI, P = 1 and ML, B = 100), and erythrinids ( U. vanini n. sp. and U. atilaiamarinoi n.…”

“…Given this context, our results corroborate those of Oliveira et al . (2021) and provide evidence that Urocleidoides may represent a non-monophyletic group.…”

“…sp., even if devoid of vaginal sclerite, are valid species for the genus. Oliveira et al (2021) in their phylogenetic analysis based on 28S rDNA have shown that some species of Urocleidoides appear nested with species of Cacatuocotyle Boeger, Domingues & Kritsky, 1997. The results of our 28S rDNA phylogenetic analysis reveal that the clade formed by Urocleidoides spp.…”

“…Among the Neotropical dactylogyrids, members of Urocleidoides Mizelle & Price, 1964 stand out for their wide distribution in host groups, with species parasitizing the gills and nasal cavities of fishes of the orders Characiformes, Gymnotiformes, Cyprinodontiformes, and Siluriformes (Oliveira et al 2020; Zago et al 2020; Freitas et al 2021; Oliveira et al 2021). The genus Urocleidoides was proposed by Mizelle & Price (1964) to accommodate U. reticulatus Mizelle & Price, 1964, collected from the gills of Poecilia reticulata Peters (Cyprinodontiformes, Poeciliidae) of the Capital Aquarium, Sacramento, California, USA.…”