Figure 20 in An Unusual, Dwarf New Species Of Neotropical Freshwater Stingray, Plesiotrygon Nana Sp. Nov., From The Upper And Mid Amazon Basin: The Second Species Of Plesiotrygon (Chondrichthyes: Potamotrygonidae)

Figure 20 (specimens depicted in B-E come from the same locality in Rio Pará). Enlarged dorsal tail spines, with very wide bases and high, acute crowns arranged in a single irregular row, are present in the vast majority of specimens of P. iwamae, but some specimens (MZUSP 59897, 108706, 108707, 108767, 108773) lack them altogether or present smaller, more scattered spines with few larger spines interspersed (Figures 19E, F, 23, 24C). Denticle morphology is similar to P. nana (Figure 22).