Composition and distribution of fishes from the Perequê-Açu river basin, Paraty, Rio de Janeiro, Southeastern Brazil

Abstract

The large number of less-known coastal drainages in the Atlantic Forest still represents an important gap in the knowledge of ichthyofauna. It is evaluated the taxonomic diversity, frequency and constancy of occurrence, and the distribution of species in the various segments of the Perequê-Açu river basin, state of Rio de Janeiro, Brazil. Twelve sampling campaigns resulted in 13,423 individuals, belonging to seven orders, 10 families, 21 genera, and 23 native species. Cyprinodontiformes and Siluriformes represented about 87.2% of the total abundance, mainly due to the contribution of Phalloceros anisophallos and Schizolecis guntheri, which account for 63.2% of the total sampled individuals. The analysis of constancy of occurrence reveals that 78.3% of the drainage species are residents, with approximately 93% of the residents of the Carrasquinho River sub-basin. The Sertões River sub-basin had the largest number of species in total: 18. The rarefaction curve did not reach an asymptote, although Chao 2 and bootstrap estimate the richness of 23.9 species and 23.7 species, respectively. The results of PERMANOVA, PCoA, and SIMPER indicate that the fish composition along the catchment is not homogeneous. The conservation status of species is also discussed, regionally, nationally, and globally.

The freshwater fishes from the Costa Verde Fluminense region of southeastern Brazil

“…Mazzoni & Silva 2006). More recently the species of Bryconamericus from the Perequê-Açu drainage was identified as B. ornaticeps (Guimarães et al 2021). However, based on our evaluation of morphological and molecular data from drainages associated with type localities we identify the species of Bryconamericus from Costa Verde Fluminense as B. ornaticeps Bizerril & Perez-Neto (1995).…”

“…A previous broad ichthyological inventory of the region did not provide catalog numbers nor pictures of the material examined (Bizerril & Primo 2001), which limits identification and distribution discussions. Other publications provide reliable records, but focused on restricted taxa (Costa 2004;Medeiros et al 2022;Souto-Santos et al 2019) or restricted drainages (Guimarães et al 2021).…”

“…DNA sequences of the COI mitochondrial gene of Bryconamericus from Costa Verde Fluminense clusters with topotypes of B. ornaticeps, and are not related to topotypes of B. microcephalus (Buckup et al, in prep). Guimarães et al (2021) provided a list of 23 species of freshwater fishes from the Perequê-Açu drainage. Our sampling from the Perequê-Açu revealed an additional species, Characidium japuhybense.…”

“…The first description of a fish species, Characidium japuhybense, from a locality situated in the Costa Verde region was published only in the middle of the 20 th Century (Travassos 1949) based on material collected in the Japuíba basin, at Angra dos Reis, a few years earlier by George Myers, Paulo Miranda-Ribeiro and Haroldo Travassos. Additional species have been described in recent decades, totaling 11 species described from specimens collected in the Costa Verde region (Table 1), but no comprehensive study of fish composition is currently available (Guimarães et al 2021). Bizerril & Primo (2001) provided three lists of fish species from river drainages of Ilha Grande Bay, the largest area in the Costa Verde Fluminense region.…”