Diversidade morfológica e genética de arraia Cururu (Potamotrygon wallacei Carvalho, Rosa e Araújo, 2016), uma espécie de igarapé

Abstract

Cururu stingray is a freshwater elasmobranch endemic to the Negro River basin, whose distribution is currently known to encompass the vicinity of the Mariuá archipelago and the region of the lower course of the Negro river near Manaus, being restricted to floodplains such as igapós and igarapés both sides of the Negro River. This sedentary behavior can contribute to the occurrence of significant intraspecific morphological and genetic variations. For this reason, in this study we investigated the differences in the shape of the cartilage, scapular and cervical-thoracic synarcual, and the genetic structure of the cururu stingray along the course of the Negro River, using geometric morphometry and nucleotide polymorphism (SNPs). We found significant differences in the analyzed structures between locations, banks and areas of the river (middle and lower Negro river), however, these variations are not related to distance isolation, but seem to be associated with the type of substrate of igapós that can be sandy-clay or with change and submerged branches. Genomic analysis suggests that the species is hierarchically structured, with a greater genetic difference between the middle and lower Rio Negro possibly due to distance isolation, and a substructure between locations in the middle Rio Negro caused by partial isolation between banks. Thus, the different patterns of intraspecific variations of the cururu stingray observed in this study occur due to different environmental pressures.