Ophiosphalma H. L. Clark 1941

Ophiosphalma H. L. Clark, 1941: 98 –99 [type species Ophiomusium planum Lyman, 1878 (= Ophiosphalma armigerum (Lyman, 1878) [by original designation].

Generic description: Disc up to 22 mm in diameter, arms up to 4 times d.d. Dorsal disc plates large, smooth, finely granulated or with small tubercles. Radial shields usually large, and fully separated except possibly in very young specimens. Ventral disc plates few, oral shields lemon-, droplet-, or dumbbell-shaped, large. Oral papillae fused or separated.

Exposed tentacle pores on lateral sutures of 3 or more ventral arm plates, often with multiple scales. Genital slits extend up to 4th arm segment, papilliform edges. Arms moniliform, lateral arm plates meeting above and below, ventral and dorsal arm plates throughout arms. 4–12 small arm spines, upper-most sometimes hooked. The following species are assigned to Ophiosphalma on the basis of possessing 3 or more pairs of exposed tentacle pores, and fully separated radial shields in adults.