Cryosignum Just & Wilson 2007

Key to species of Cryosignum

1. Pereionite 1–7 dorsal surface smooth; antennula article 1 length subequal to article 2, or longer than article 2............ 2

- Pereionite 1–7 dorsal surface with transverse ridges; antennula article 1 shorter than article 2......................... 3

2. Head frontal margin nearly straight with angular corners; pereionites 1–7 lateral margin rounded, smooth; pleotelson lateral margin with proximal neck before convex margin; antennula articles 3 and 5–6 of subequal length, longer than article 4............................................................................ Cryosignum nordenstami sp. nov.

- Head front margin broadly convex, without angular corners; pereionite 1 lateral margin broadly rounded with small concavity; pereionite 1–4 lateral margins denticulate; pleotelson lateral margin convex; antennula articles 5–6 of subequal length, longer than articles 3–4....................................................... Cryosignum latifrons (Menzies, 1962)

3. Head frontal margin nearly straight laterally, with angular lateral corners adjacent to antennae; eyestalks shaft constricted proximally; pleotelson laterally rounded, with inflection between proximal and lateral margins.............................................................................................. Cryosignum incisum (Richardson, 1908)

- Head frontal margin broadly rounded, without angular lateral corners adjacent to antennae; eyestalks shaft before apex approximately parallel; pleotelson laterally rounded with inflection and distinct neck between lateral and proximal margins............................................................................... Cryosignum lunatum (Hale, 1937)