No abstract

The genus Psalidodon Eigenmann, 1911 (Characiformes Characidae) is a fish group with great diversity, expressed at the chromosomal, genetic and taxonomic level. The genus is markedby events of allopatric and vicariant evolution, by the formation of complexes of species andby wide geographical distribution. Both in these fish and other organisms, the association ofstudies with molecular markers and geometric morphometric techniques are useful in delimitingsignificantly evolutionary units (ESU). In this work, we performed maximum likelihood esti-mates (MLE) from mitochondrial Cyt b gene sequences and canonical variables (CVA) from13 landmarks in eight populations of P. aff. paranae Eigenmann, 1914. The analysis of Max-imum likelihood resulted in the structuring of populations in two different clades, one of whichwas composed only of individuals from a small population inhabiting a stream with approxi-mately two km of length, demonstrating their clear distinction from the other populations. Theanalysis of canonical variation demonstrated the complete structuring of this population, andthe position of each clade in the morpho-space was congruent with the topography observedin the MLE. Based on the results found, the existence of a new endemic species of the genusPsalidodon is evident.

No abstract

The fishes of the Chiasmodontidae family, known as swallower fishes, are species adapted to live in deep seas. Several studies have shown the proximity of this family to Tetragonuridae and Amarsipidae. However, the phylogenetic position of this clade related to other Pelagiaria groups remains uncertain even when phylogenomic studies are employed. Since the low number of published mitogenomes, our study aimed to assemble six new mitochondrial genomes of Chiasmodontidae from database libraries to expand the discussion regarding the phylogeny of this group within Scombriformes. As expected, the composition and organization of mitogenomes were stable among the analyzed species, although we detected repetitive sequences in the D-loop of species of the genus Kali not seen in Chiasmodon, Dysalotus, and Pseudoscopelus. Our phylogeny incorporating 51 mitogenomes from several families of Scombriformes, including nine chiasmodontids, recovered interfamilial relationships well established in previous studies, including a clade containing Chiasmodontidae, Amarsipidae, and Tetragonuridae. However, phylogenetic relationships between larger clades remain unclear, with disagreements between different phylogenomic studies. We argue that such inconsistencies are not only due to biases and limitations in the data but mainly to complex biological events in the adaptive irradiation of Scombriformes after the Cretaceous-Paleogene extinction event.

The genus Psalidodon, in turn, has shown great potential in studies involving the variation of form associated with genetic characteristics (Alves et al., 2020;Rocha et al., 2019). Rocha et al. (2019) demonstrated the correspondence between molecular data and body shape variation in different mitochondrial lineages of P. rivularis and P. paranae Eigenmann, 1914. The study also reinforced the taxonomic validity between the two species, both through molecular and morphometric data.Approaches involving cytogenetic markers together with geometric morphometry were used by Castro et al.

We are presenting the complete mitogenomes of eight fish species/cytotypes from Neotropical region belonging to the Astyanax and Psalidodon genus: A. aeneus, A. altiparanae, P. fasciatus (from two locations - Upper Parana and Sao Francisco river basins), A. lacustris, P. rivularis (two cytotypes) and P. rioparanaibano. We perform the whole-genome sequencing for six of these species in a Novaseq 6000 - by Illumina, meanwhile two genomes were assembled from raw data available in databases. Plus, we reassembled and annotated the mitochondrial genomes for A. mexicanus and P. paranae, both already described and with raw data available online. All the genomes presented the same organization, with 13 protein-coding genes, 22 tRNA genes and two rRNA genes. Aiming to contribute to the understanding of the several cryptic species complexes and phylogeny of the genus, we perform Bayesian analysis using the 13 protein-coding genes from these species, plus Deuterodon giton and using a Brycon species as outgroup.