A new species of Moenkhausia (Characiformes: Characidae) from the rio Madeira basin, Brazil, with comments on the evolution and development of the trunk lateral line system in characids

Abstract

A new species of Moenkhausia is described from the rio Machado drainage, Amazon basin, Brazil. It is diagnosed from congeners by its color pattern, consisting of the concentration of chromatophores on the anterior portion of body scales, the horizontally elongate blotch on caudal peduncle, a bright golden coloration of the dorsal portion of eye when alive, and a dark line crossing the eye horizontally. The new species has variable morphology regarding trunk lateral-line canals. Most fully grown individuals do not have enclosed bony tube in many lateral line scales, resembling early developmental stages of tube formation of other species. This paedomorphic condition is interpreted as a result of developmental truncation. Such evolutionary process may have been responsible for the presence of distinct levels of trunk lateral line reductions in small characids. Variation in this feature is common, even between the sides of the same individual. We reassert that the degree of trunk lateral-line tube development must be used with care in taxonomic and phylogenetic studies, because reductions in the laterosensory system may constitute parallel loss in the Characidae. We suggest the new species to be categorized Near Threatened due to the restricted geographical distribution and continuing decline in habitat quality.

On a new colorful species of Moenkhausia (Characiformes: Characidae) from the upper rio Madeira basin at the Chapada dos Parecis, Brazil, with comments on its conservation and putative biogeographic history

“…If any, the number of c&s specimens with their L S range is indicated. Comparative materials are listed in Dagosta and Marinho (2016) and Marinho et al (2021), except Moenkhausia diamantina Benine, Castro & Santos, 2007: MZUSP 49248, 5 ex, rio Paraguaçu basin, Bahia, Brazil, and M. tergimacula Lucena & Lucena, 1999: MZUSP 18176, 4 ex, rio Tocantins basin, Pará Brazil. Data of M. bellasomiosa Soares, Lima, Bastos & Rapp Py‐Daniel, 2019 were taken in the original description.…”

“…Revisionary studies (e.g., Marinho & Lageani, 2016; Petrolli & Benine, 2015) and descriptions of new species have helped to elucidate the real diversity of the genus. In the last 10 years, 22 new species of Moenkhausia were described (e.g., Marinho et al, 2021; Pastana & Dagosta, 2014), representing 22% of the known diversity.…”

Fish fauna of moderate altitude from first order stream in upper Rio Machado, Rondônia, Brazil

“…Its headwaters are located at the southeastern border of Rondônia at Chapada dos Parecis, a watershed between three river basins (Madeira, Paraguay and Tapajós). This region is also the type locality of many recently described fish species (Fisch-Müller et al, 2005;Wingert & Malabarba, 2011;Ohara & Lima, 2015;Ohara & Marinho, 2016;Bockmann & Reis, 2021;Marinho et al, 2021). The majority of these species seem to have very restricted distribution, since they were not recorded during previous surveys in the Rio Machado basin (e.g., Perin et al, 2007;Casatti et al, 2013;Costa et al, 2017), in other rivers of the Rio Madeira basin (e.g., Rapp Py-Daniel et al, 2007;Araújo et al, 2009;Pedroza et al, 2012;Queiroz et al, 2013a, b;Vieira et al, 2016;Anjos et al, 2019;Oliveira et al, 2020), or in neighboring drainages (Ohara & Loeb, 2016;Ohara et al, 2017).…”

Relações filogenéticas em Xenurobrycon Myers & Miranda-Ribeiro e discussão sobre miniaturização no gênero (Characiformes: Characidae: Stevardiinae)

“…Como mencionado, as espécies de Xenurobrycon apresentam acentuado dimorfismo sexual e também uma série de características relacionadas ao tamanho do corpo. Os efeitos da diminuição do tamanho do corpo na morfologia de peixes neotropicais foram durante anos gradualmente explorados e, especialmente, na última década, importantes trabalhos impulsionaram e desenvolveram pesquisas sobre o tema (Mattox, et al, 2013;2020;Toledo-Piza et al, 2014;Marinho, 2017;Camelier et al, 2018;Abrahão et al, 2019;Marinho et al, 2021;Mattox & Conway, 2021). No estudo publicado por Mattox et al (2016), os autores comparam o desenvolvimento ósseo de um Bryconidae, táxon proximamente relacionado à Characidae, (Salminus brasiliensis) com uma espécie miniatura de Characidae (Priocharax sp.…”