Plagiogeneion rubyfishes have a body which has a
standard length of 2.8 to 3.6 times its depth. They have a continuous
dorsal fin which is only slightluy incised at the front of the soft-rayed portion of the fin. The final spines of both the dorsal and anal fins are not longer than the penultimate spines. They lack a fleshy ridge on the side of the
caudal peduncle and do not have a groove or fleshy protuberance on rear margin of the gill cavity. The upper spine on
operculum is an obtuse flat point or developed as an acute spine. They have a small number of small sharp teeth at the front of the jaws and they may have similar teeth on the
vomer and
palatines. The
rubyfish (
P. rubiginosum) is the largest species, attaining a maximum published
total length of , while the smallest is
P. unispina at a maximum published standard length of . ==References==