a scobina has very different spottings:
http://www.freshwaterstingray.com/images/rays/100-0007_IMG.jpg
http://www.freshwaterstingray.com/images/rays/100-0008_IMG.jpg
http://www.freshwaterstingray.com/images/rays/100-0007_IMG.jpg
http://www.freshwaterstingray.com/images/rays/100-0008_IMG.jpg