(Leuckart, 1859)
Body small. Caudal furca short, in outline almost an equilateral triangle (Pleopis polyphemoides, female; Pleopis polyphemoides, male).
Antennae: exopod segments 1-4 with 0,1,2,4 swimming setae. Exopods of thoracic limbs l--4 with 3,3,3,2 setae, respectively (Pleopis polyphemoides, exopods).
Female brood chamber varying from hemispherical to spherical (Pleopis polyphemoides, female). Resting eggs small, spherical, 0.15-0.21 mm in diameter (mean 0.18 mm); greenish-brown; numerous small pores scattered throughout outer egg membrane (pores crater--shaped as seen in SEM); perimeter obscured with the ornamentation of membrane.
Total length female (standard length): 0.3-0.7 mm (0.2-0.6 mm).
Total length male: 0.4-0.7 mm (0.4.-0.7 mm).