There is a thread in the General Aquarium section about a new stingray species. "Pan cake" rays were mentioned, of the genus Heliotrygon, and described in 2011. While poking around for info on them, I came across another species described last year as Potamotrygon limai. Any one heard of these? Seem similar to scobina.
http://shark-references.com/species/view/Potamotrygon-limai
http://shark-references.com/species/view/Potamotrygon-limai