Rhamdia

Abstract: The eustatic movements triggered by glaciations during the Quaternary have shaped the landscape of Brazilian Atlantic Coast. Cyclic sea-level changes either isolated or connected freshwater fish populations, impacting their distribution and diversification. Rhamdia quelen has been widely recorded from the Brazilian Atlantic Coastal rivers, but it is also considered a species complex. A phylogeographic study carried out using three molecular markers of mtDNA and one of nDNA in the populations of Rhamdia from the hydrographic basins of Southern Atlantic Coast of Brazil recovered three evolutionarily distinct groups: one represented by the populations found in lowlands of all studied watersheds; the second group composed of populations found in the upper tributaries of the rio Ararangua, rio Mampituba and rio Tramandai; and a third group found exclusively in the upper portions of rio Tubarao. The genetic divergences among these three lineages of Rhamdia is discussed according to sea level changes in the Quaternary. Two new species of Rhamdia are diagnosed and described based on morphological and molecular evidence.

Abstract: The jundia (Rhamdia quelen, Quoy and Gaimard) is an endemic South American fish species. Because this species supports cold winters and grows faster during warm months, it has begun to be viewed as an ideal species for fish production in southern South America. In the present study, jundia oocytes used were obtained by extrusion from females after hormone injection. Soon after hydration, the eggs were transferred to 50 L conic glass incubators, with constant and controlled water influx. Samples of fertilized eggs were transferred to Petri dishes and, examined under a stereoscopic microscope, were spherical, demersal, and non-adhesive with defined perivitelline space and resistant chorion. Cleavage stages occurred during the first 3.5 h. After hatching, larvae were transferred to 200 L glass fiber incubators. First signs of embryo movement were observed 21 h after fertilization; larval eclosion occurred 30.5 h after fertilization. Present findings may provide a basis for studies aimed at determining the complete ontogeny of jundia and may be useful in eco-toxicological studies.

Abstract: More than 100 species have been referred to Rhamdia since its description, but in the last revision of the genus more than two decades ago, only eleven species have been considered as valid Rhamdia quelen was then redefined to include 47 junior synonyms, resulting in a species with a large distribution in the Neotropics, from Mexico to Argentina Populations of Rhamdia from west of the Andes have been recently removed from the synonymy of R quelen, and currently there are 27 species recognized in the genus Most cis-Andean populations, however, remain referred to the R quelen species complex In this paper, we use species delimitation methods and multilocus phylogenetic analyses to delimit the species contained in the R quelen species complex in cis-Andean river drainages Eighteen MOTUs in the gene tree were recovered with high support We further demonstrate that the previous designation of a neotype for R quelen is invalid, and has to be replaced by the proper designation of a neotype from the type locality of the species The neotype is designated herein and R quelen is diagnosed and redescribed