1	Genital papillae present (Fig. 9b)	2
–	Genital papillae absent (Fig. 10b)	3
2	A distinct line forming a reticulated pattern on the aboral surface of the disk (Fig. 9a). Arm spines markedly compressed, with apex blunt. With dark bands on arm segment separated by three-six light bands (Fig. 9a, d)	Ophionereis reticulata
–	Dark blotches on aboral surface of disk. Arm spines markedly compressed. Dark bands occupying two or three arm segments, separated by one light bands	Ophionereis squamulosa
3	Sometimes several superposed accessory dorsal arm plate are observed. Three arm spines longer than arm segment (Fig. 10i), match-shaped	Ophionereis olivacea
–	Accessory dorsal arm plates small (Fig. 10a, d). Three long, thin spines on arm (Fig. 10d, e)	Ophionereis dolabriformis