there is a great amount of confusion going on with these rays at the moment.
i have a pair and they were shipped in as "peruvian hystrix", ive also seen them listed as peruvian flowers as well.
ive just been calling mine Potamotrygon sp, "peru".
i have a feeling they are closely related to motoro but it seems like they are there own species and need a PROPER name so every one can id them once and for all.