Euapta

Östergren, 1898

6 species

Tentacles pinnate 15-16, occasionally 16; individuals not fully mature often have 12, 13, or 14. Digits numerous (10-35) on each side. Cartilaginous ring usually wanting. Polian vesicles numerous. Stone canals one or more. Sense organs in the form of pigment eyes at base of tentacles on oral disc, often present. Stock of anchors distinctly branched; arms smooth; vertex with some minute knobs. Anchor plates with large central hole surrounded by six (rarely seven) other large holes, all more or less dentate, and with several holes of variable size and arrangement (one on each side, large), but with smooth margins, at posterior end, where a well formed and arched bow crosses outer surface of plate. (Clark, 1907)

Euapta goddeffroyi is the type species, the best way to separate Euapta from Opheodesoma is the large number of stone canals in Opheodesoma and the size of the rods on the oral disc and tentacles. (Heding, 1928)

Tentacles 15, with 10 to 35 digits on each side, cartilaginous ring usually present. Numerous Polian vesicles, stone canal one or more; often pigment eyes at the base of tentacles. Stock of anchor distinctly branched, arms smooth; vertex with some minute knobs; anchor plates with large central holes surrounded by 6 rarely 7 other large holes, all more dentate, and with several holes of variable size and arrangement (one on each side large) but with smooth margin at posterior end, where a well formed and arched bow crosses the outer surface of the plate. (Deichmann, 1930)