loach43;961891; said:Another quick note on Pterygoplichthys. They can be IDed pretty quick by counting the # of fin rays in the dorsal. More than 10 rays means that they are atleast in that genus. One nice thing is that juvies even posess this trait which is WONDERFUL, especially since it's often hard to figure out what your looking at based on coloration alone. There are soooo many shades, colors and patterns. Worse than that, these attributes change with growth.
The 9+ dorsal rays differs from all hypostomines except Acanthicus, Chaetostoma, Delturus, and Upsilodus in usually having 10+ dorsal fin rays (rarely 9). Acanthicus differs from most Pterygoplichthys by having keels of large odontodes on the lateral plates. Pterygoplichthys differs from Delturus and Upsilodus by lacking a postdorsal ridge formed of three or more median, unpaired plates and by a fully plated (vs. naked) abdomen, and from Chaetostoma by having three (occasionally two) plates between the suprapreopercle and the exposed opercle (vs. one), an exposed nuchal plate (vs. covered by plates), an exposed spinelet (vs. covered by skin), and a fully plated abdomen (vs. naked).
