I believe it is an adult male P. Reticulata that had to be seperated from an aggressive male P. Motoro..
Looks like AJfromAT's adult retics.. it seems that one variations gets a washed out pattern at adulthood.. Judging by his seemingly "maxed out" size for those irregularly large claspers, thats why I think it's a retic.. the tail obviously wouldn't be in tact because of it's poor shape.. but my male has a damaged tail that is bladed just like that one.
Also, notice the 'reticulated' pattern only around the outer disc margin.. but now that I take a second look, the other ray might be more 'blotchy' like a Humerosa/Orbignyi. H'rm.
Anyways.. I could be wrong. I think it also might be a Hystrix.. hard to tell without a better pic closer up.. Is the glass dirty? Could be just some ugly brown peru ray?
my guess is strictly just a guess but in comparison from this site and the one pictured, it looks like an orbignyi which has the patterns behind the eyes and it is also distinct in the picture given. looking at the humerosa from the site, it looks like the humerosa lacks that pattern. but then again i'm in question about my orbignyi/humerosa/whatever....lol