Description of a new catfish genus (Siluriformes, Loricariidae) from the Tocantins River basin in central Brazil, with comments on the historical zoogeography of the new taxon

Abstract

This study presents the description of a new genus of the catfish subfamily Neoplecostominae from the Tocantins River basin. It can be distinguished from other neoplecostomine genera by the presence of (1) three hypertrophied bicuspid odontodes on the lateral portion of the body (character apparently present in mature males); (2) a large area without odontodes around the snout; (3) a post-dorsal ridge on the caudal peduncle; (4) a straight tooth series in the dentary and premaxillary rows; (5) the absence of abdominal plates; (6) a conspicuous series of enlarged papillae just posterior to the dentary teeth; and (7) caudal peduncle ellipsoid in cross section. We used maximum likelihood and Bayesian methods to estimate a time-calibrated tree with the published data on 116 loricariid species using one nuclear and three mitochondrial genes, and we used parametric biogeographic analyses (DEC and DECj models) to estimate ancestral geographic ranges and to infer the colonization routes of the new genus and the other neoplecostomines in the Tocantins River and the hydrographic systems of southeastern Brazil. Our phylogenetic results indicate that the new genus and species is a sister taxon of all the other members of the Neoplecostominae, originating during the Eocene at 47.5 Mya (32.7–64.5 Mya 95% HPD). The present distribution of the new genus and other neoplecostomines may be the result of a historical connection between the drainage basins of the Paraguay and Paraná rivers and the Amazon basin, mainly through headwater captures.

Parotocinclus jacksoni, a new hypoptopomatine catfish (Siluriformes: Loricariidae) from the Rio Mamanguape basin, north‐eastern Brazil

“…The genus Parotocinclus Eigenmann & Eigenmann, 1889 belongs to Hypoptopomatinae, a subfamily of Loricariidae, which is a complex clade due to divergent phylogenetic hypotheses (Cramer et al ., 2011; Lujan et al ., 2015; Roxo et al ., 2019a). The relationships between subfamily genera are controversial (Roxo et al ., 2019a): Parotocinclus is a genus with unclear taxonomic limits and is therefore considered paraphyletic within Hypoptopomatinae, even in the face of advances in morphological, molecular and genomic studies (Cramer et al ., 2011; Martins et al ., 2014; Roxo et al ., 2019a; Silva et al ., 2016). Parotocinclus is the most diverse genus of the subfamily, and in the last decade a total of 14 species were described, more than one species per year, encompassing 38 species of the genus (Fricke et al ., 2021; Lehmann et al ., 2020; Lehmann & Reis, 2012; Pereira et al ., 2019; Silva‐Junior et al ., 2020).…”

“…The genus Parotocinclus Eigenmann & Eigenmann, 1889 belongs to Hypoptopomatinae, a subfamily of Loricariidae, which is a complex clade due to divergent phylogenetic hypotheses (Cramer et al, 2011;Lujan et al, 2015;Roxo et al, 2019a). The relationships between subfamily genera are controversial (Roxo et al, 2019a): Parotocinclus is a genus with unclear taxonomic limits and is therefore considered paraphyletic within Hypoptopomatinae, even in the face of advances in morphological, molecular and genomic studies (Cramer et al, 2011;Martins et al, 2014;Roxo et al, 2019a;Silva et al, 2016).…”