There is a considerable variation in size within this genus, up to over 20 cm in
standard length, in the case of species such as
P. pectegenitor. Most species are not able to evert their cheek plates. In some species,
odontodes on the snout may sometimes be extremely hypertrophied. Most species are dark gray, with lighter colouration on the abdomen. In some species, there are light-colored spots or blotches on the sides. Usually, the fins are similarly colored, but in some species there are bands on the
caudal fin or an orange or red edging to the
dorsal fin and caudal fin. ==References==