Two new species of freshwater stingrays of the genus Paratrygon (Chondrichthyes: Potamotrygonidae) from the Orinoco basin, with comments on the taxonomy of Paratrygon aiereba

Abstract

The genus Paratrygon, currently recognized as the sole monotypic genus of the family Potamotrygonidae, has a considerably greater diversity than previously indicated, including molecular studies, which supported P. aiereba (hitherto the only recognized species in the genus) as a possible species complex. Here we describe two new species of the genus that are both endemic to and sympatric in the Orinoco basin. Paratrygon aiereba, type species of the genus, is now restricted to the Amazon basin. Both new species are identified and defined through morphological characters such as coloration, dermal denticle morphology, arrangement of thorns, distribution and morphology of ventral lateral line canals, morphology of skeletal elements, and morphometrics. An extensive comparison of these characters between the new species herein described and P. aiereba is presented. Finally, a taxonomic reappraisal of P. aiereba is provided through a revision of preserved material and its original description, plus new evidence about its type-locatity, collectors, and a reconsideration of the destination of its type-specimen.

A new species of Astronotus (Teleostei, Cichlidae) from the Orinoco River and Gulf of Paria basins, northern South America

“…Likewise, Buitrago-Suárez and Burr (2007) described seven new species of Pseudoplatystoma Bleeker, 1862 from two species, which were previously considered to have a pan-Amazonian distribution, and Escobar et al (2019) described a new species of Piaractus Eigenmann, 1903 from the Orinoco River basin, from a species previously thought widely distributed in the Amazon basin. More recently, Loboda et al (2021) described two new species of freshwater rays of the genus Paratrygon Duméril 1865 from the Orinoco River basin from a single species with a shared distribution for the Orinoco and Amazon river basins. Kullander (1986) and Colatreli et al (2012) considered that there may be several species within the genus Astronotus, and particularly Colatreli et al (2012) tested this hypothesis by using the ABGD method, delimiting five different lineages in Astronotus populations from the Amazon River basin that could represent candidate species.…”

Estimating intrinsic susceptibility to extinction when little ecological information is available: The case of Neotropical freshwater stingrays (Chondrichthyes: Potamotrygoninae)

“…1 and sp. 2, have since been described as Paratrygon orinocensis and P. parvaspina , respectively (Loboda et al, 2021), and the others are likely to be formally described in the near future. They are distinguishable based on morphology and DNA (Frederico et al, 2012; Loboda, 2016; Rizo‐Fuentes et al, 2021).…”

Market surveys and social media provide confirmation of the endangered giant freshwater whipray Urogymnus polylepis in Myanmar

“…Among freshwater fishes, there is very little information on the conservation status of non‐marine elasmobranchs (Grant et al ., 2019). Elasmobranchs that use freshwater environments are either freshwater obligates (45 described species, Grant et al ., 2019; Loboda et al ., 2021) or euryhaline generalists (10 species), which use a range of freshwater, estuarine and marine habitats throughout their life history (Grant et al ., 2019). In the Indo‐Pacific, most non‐marine elasmobranchs are threatened with extinction on the IUCN Red List of Threatened Species (hereafter IUCN Red List, IUCN.…”