Dana, 1853
Length 5-6 mm. Body slender, without convexity along back. Head triangular. Eyes more or less round. ANT I with accessory flagellum equalling length of ART 1 of main flagellum (the latter composed of several fused ART). Segment I of pereon shorter than segment II, VI as long as VII. ART 2 of P V and VI truncate below. P VI as long as P VII. Telson cleft. Live animals more or less entirely intense blue, colour deepest along venter. For discussion of validity of Synopia gracilis see (Barnard, 1972).