Length 4-6 mm (Synopia scheelana 1). Body slender. Head triangular. Eyes elongate. ANT I with secondary flagellum shorter than ART 1 of main flagellum (the latter composed of several fused ART). Segment I of pereon as long as segment II, VI shorter than VII, which is longest. ART 2 of P V ovate, of P VI almost circular. Telson cleft (Synopia scheelana 3) (see key). Live animals blue or hyaline.