A taxonomic and morphological redescription of Potamotrygon falkneri Castex & Maciel, 1963 (Chondrichthyes: Myliobatiformes: Potamotrygonidae)

Abstract

A taxonomic revision of two nominal species of freshwater stingrays of the genus Potamotrygon previously considered valid, Potamotrygon falkneri Maciel, 1963 and Potamotrygon castexi Castello &Yagolkowski, 1969, was conducted based on a detailed analysis of external and internal morphology, including a morphometric and meristic study of specimens from the recorded range of both species. The taxonomic status of the nominal species P. menchacai Achenbach, 1967, treated by previous authors as a junior synonym of P. falkneri, was also evaluated. These nominal species, which constitute what has been called the falkneri-castexi complex, were found to represent examples of chromatic variation present in a single species, given that intermediate patterns of coloration are common and the remaining characters analyzed are not consistent enough for separation at the specific level. Consequently, Potamotrygon falkneri is considered valid, whereas the nominal species Potamotrygon castexi and Potamotrygon menchacai are concluded to be junior synonyms of P. falkneri. Additionally, a putative new species is identified from the río Madre de Díos in Peru, which has some characters that do not correspond to P. falkneri. This species, known from few individuals, is here provisionally treated as Potamotrygon sp. Uma revisão taxonômica de duas espécies nominais de raias de água doce do gênero Potamotrygon previamente consideradas válidas, Potamotrygon falkneri Castex & Maciel, 1963 e Potamotrygon castexi Castello & Yagolkowski, 1969, foi realizada baseada numa análise detalhada abrangendo aspectos da morfologia externa e interna, incluindo um estudo morfométrico e merístico de espécimes provenientes da distribuição registrada dessas espécies. Além dessas espécies, o status taxonômico da espécie nominal Potamotrygon menchacai Achenbach, 1967, tratada por autores prévios como sinônimo júnior de Potamotrygon falkneri, foi avaliado. As espécies nominais que constituem o que foi chamado de complexo falkneri-castexi representam exemplos da variação cromática encontrados em uma única espécie, uma vez que ocorrem padrões intermediários de coloração e os caracteres restantes não são consistentes para separação em nível específico. Sendo assim, a espécie nominal P. falkneri é considerada válida e as espécies nominais P. castexi e P. menchacai sinônimos juniores desta. Adicionalmente, uma possível espécie nova é apresentada do río Madre de Dios no Peru, sendo esta portadora de alguns caracteres destoantes de P. falkneri. Essa espécie, conhecida de poucos indivíduos, é tratada aqui provisoriamente como Potamotrygon sp.

Systematic revision of the Potamotrygon motoro (Müller & Henle, 1841) species complex in the Paraná-Paraguay basin, with description of two new ocellated species (Chondrichthyes: Myliobatiformes: Potamotrygonidae)

“…Similar to other potamotrygonid species (e.g., Potamotrygon falkneri; Silva & Carvalho, 2011a, 2011b, P. amandae presents a variable pattern of dorsal disc coloration. Within the brown and gray patterns, the variation can be composed of ocelli, small, vermiculated marks or the total absence of specific dorsal patterns.…”

Activity and habitat use of two species of stingrays (Myliobatiformes: Potamotrygonidae) in the upper Paraná River basin, Southeastern Brazil

“…2). Potamotrygon falkneri is endemic to the Paraná-Paraguay River basin and its specific identity is well corroborated (Rosa, 1985;Silva & Carvalho, 2011). Potamotrygon motoro integrate a set of morphotypes widely distributed through the rivers of South America and at least one new form was identified in the Paraná River basin, requiring further investigation for its determination (Rosa, 1985;Loboda, 2010).…”

A new species of Neotropical freshwater stingray of the genus Potamotrygon Garman, 1877 from the Río Madrede Díos, Peru (Chondrichthyes: Potamotrygonidae)

“…This species was discovered during the preparation of a taxonomic revision of Potamotrygon falkneri Castex & Maciel, 1963, in which it was presented as Potamotrygon sp. (Silva & Carvalho, 2011). However, after a thorough morphological analysis of this form (more in-depth than in Silva & Carvalho, 2011), and a re-examination of material of Potamotrygon falkneri, it became evident that Potamotrygon sp.…”