Length to 17 mm (females), to 9 mm (males). In females (Phronima curvipes 1) pleon and urosoma (including UR) combined 0.90±0.05 times as long as head and pleon combined; pleonite I 0.70±0.06 times as long as pereonite VII. ART 2 of P V in reversed "S" shape (unique character, Phronima curvipes 2), a strong process pointed backward at distal end of posterior margin; ART 4 globular, longer than wide; ART 5 longer than wide, posterior margin parallel to anterior (except for rounded proximal third); carpal process strong, protruded downward, carpal tubercle strong, almost single (with weak, poorly separated anterior tooth) or single, with 6-7 tooth-like projections; ART 6 longer than palmar margin of ART 5, with weak metacarpal tubercle. Endopodite of UR II at least one-forth shorter than exopodite.
In males pleon and urosoma (including UR) combined 1.08±0.08 times as long as head and pleon combined; pleonite I 0.92±0.07 times as long as pereonite VII. ANT II well-developed, subequal to ANT I, flagellum 7-9 articulated. Posterior margin of ART 2 of P V slightly curved, as in female; ART 4 slightly wider than long, posterior margin semicircular in dorsal two-thirds, oblique in ventral third; ART 5 wider than long, proximal posterior corner highly produced, against oblique posterior margin of ART 4, carpal process moderate, bent slightly backward, carpal tubercle with separate anterior tooth and 4-5 closely contiguous tooth-like projections. Endopodite of UR II at least one-half as short as exopodite.