Thomson, 1880
Length to 15 mm, in Antarctic waters to 36 mm. Pereonite VII, all pleonites, and urosomite I carinate; pereonite VII with weak dorsal tooth, pleonites I and II (but not III) with strong dorsal teeth. Lateral lobes of head broadly rounded (as in Eusirus perdentatus). Eyes pear-like (oval in young), nearly fused dorsally, eyes larger in males than in females. ANT peduncles calceolate. ANT I slightly longer than II, reaching pleon. ART 2 of peduncle of ANT I as long as, or slightly shorter than, ART 1; ART 1 with 3 sharp distal denticles; ART 2 with 3-5 denticles. Accessory flagellum shorter than ART 3 of peduncle of ANT I. ART 4 of P III-IV twice as long as ART 5. CX IV as high as pereonite IV. Posteroventral corner of epimeral plate III at approximately 90°, rounded; margins finely serrate. Telson twice as long as wide; with exception of large antarctic specimens, cleft a third of length or more, in antarctic animals cleft one quarter or less.