A new miniature Pristella (Actinopterygii: Characiformes: Characidae) with reversed sexual dimorphism from the rio Tocantins and rio São Francisco basins, Brazil

Abstract

A new species of the genus Pristella Eigenmann, 1908 (Pristella crinogi sp. nov.) is described from the middle rio Tocantins and middle rio São Francisco basins, Brazil. The new species can be diagnosed from its two congeners, Pristella ariporo Conde-Saldaña, Albornoz-Garzón, García-Melo, Villa-Navarro, Mirande, and Lima, 2019 and Pristella maxillaris (Ulrey, 1894), by a combination of color pattern and teeth morphology characters. A phylogenetic analysis of the genus recovered P. crinogi as the sister taxa of P. ariporo. Pristella crinogi, along with P. ariporo, are the first characiform fishes, and one of the first bony fishes, to be reported as presenting a reversed sexual dimorphism, with females presenting a more developed color pattern than males. Comments on the miniaturization of the species, as well as remarks on the biogeography of the genus Pristella, are presented.

Sperm phylogeny of Characidae (Teleostei, Characiformes)

“…In Mirande (2009Mirande ( , 2010Mirande ( , 2017Mirande ( , 2019 and Ferreira et al (2021), a stability criterion was used, looking for the hypothesis that was less affected by the use of different weighting schemes and/or strenghts. In Terán et al (2020) and Lima et al (2021), instead, we implemented a criterion based on overall parsimony, by comparing the fit of each most parsimonious tree on the complete set of analytical conditions, including those in which it is either optimal or suboptimal. Herein, a third criterion was implemented after noting that the number of steps of the morphological characters varied when using each of the weighting schemes and strengths in a way that differed from the total number of steps for the trees.…”

“…As this contribution is focused on the impact of the reproductive characters, the final dataset includes only the species with data in that partition, leaving out of the analysis many species included in previous combined phylogenetic analyses of the family (e.g., Lima et al, 2021; Mirande, 2019; Terán et al, 2020). The inclusion of these species would add many polymorphic optimizations in the reproductive characters and, hence, less synapomorphies attributable to specific clades.…”

“…These trees are alternative hypotheses on the phylogeny of the Characidae, obtained under different arguably reasonable analytical parameters. The first of these trees (GRO15) represents a conservative solution, given that it was selected from the same criterion than in previous articles (Lima et al, 2021;Terán et al, 2020) and, excepting for details, the obtained hypothesis agrees with the currently accepted relationships of the Characidae (e.g., Melo et al, 2022;Mirande, 2019). The second hypothesis (SEP15) had the best correlation with the morphological data but, given that this is a different metacriterion than those used previously to select between optimal trees under different parameters, the tree topology is also relatively more divergent from the currently accepted phylogeny of the Characidae.…”

“…Her results have shown that reproductive characters were potentially useful to reconstruct the phylogenetic relationships of the Characidae but that, as presumed, they should be combined with data from other sources, as general morphology or RNA/DNA molecular data. In this contribution we analyse revised data from Baicere‐Silva (2013) in combination with morphological and molecular information from the latest combined phylogenetic analyses of the Characidae (Lima et al, 2021; Mirande, 2019; Terán et al, 2020). The aims of this contribution are to assess the utility of reproductive characters as sources of synapomorphies and to understand how these characters evolved in the family.…”

Osteology of Tucanoichthys tucano Géry and Römer, an enigmatic miniature fish from the Amazon basin, Brazil (Teleostei: Characiformes: Characidae)

“…Miniaturization, the evolution of extremely small adult body size, is a common phenomenon among freshwater fishes, especially in the Neotropics from where over 200 miniature species (≤26 mm in standard length [SL] sensu Weitzman and Vari 1988) are already known (Toledo-Piza et al 2014) and new species continue to be discovered annually (e.g., Henschel 2016;Mendonça et al 2016;Carvalho et al 2016Carvalho et al , 2017Calegari and Reis 2017;Pastana et al 2017;Valdesalici and Nielsen 2017;Caires and Toledo-Piza 2018;Camelier et al 2018;Jerep et al 2018;Abrahão et al 2019;Costa et al 2019;Ohara et al 2019;Henschel et al 2020aHenschel et al , 2020bMattox et al 2020Mattox et al , 2021Lima et al 2021;Vieira and Netto-Ferreira 2021). Miniaturization is frequently associated with one of two evolutionary processes: (1) a simple evolutionary decrease in body size resulting in miniature versions of larger close relatives (the so-called proportional dwarves of Gould [1971]); and (2) shifts in the relative timing of gonadal development in relation to somatic development (progenesis) resulting in species with developmentally truncated adults that resemble the larval stages of closely related taxa (so-called developmentally truncated miniatures of Rüber et al [2007]; ; Britz et al [2014]).…”