Müller, 1906
Diagnosis
Small species with carapace nearly oval in lateral aspect. Shoulder vaults well developed showing clearly in profile. The posterior margin forming an oblique angle with the dorsal margin and curving smoothly into the ventral margin (C. brachyaskos Habitus 1, C. brachyaskos Habitus 3). Sculpture of faint longitudinal parallel striae on the dorsal surface of the rostra and parallel to anterior margin below the incisure. Right asymmetrical gland opens at the postero-ventral corner. Left asymmetrical gland opening on small but clearly visible tubercle about a sixth of the length anterior of the hind end of the hinge.
Female, frontal organ long, undifferentiated, slightly curved downwards (C. brachyaskos 1). Capitulum terminally finely hirsute on its under-surface; rounded end with a small pointed process in occasional specimens.
Male, frontal organ with down-turned capitulum, slightly sinuate, and spinous on its proximal ventral half (C. brachyaskos 3). First antenna "e" seta armature of a double line of small conical pegs, "b" and "d" setae exceptionally short, about half length of "e" seta, "a" seta almost as long as the limb. Second antenna endopodite sensory short, only a third the length of "f" and "g" setae.
Remarks
Deeper-living specimens tend to be larger than shallower-living. This merits investigation to examine if there is confusion of two closely related forms.
Distribution
Widely distributed at deep mesopelagic to bathypelagic depths in all oceans; usually begins to appear in samples at depths of around 800m. 1, 2, 3 (R.R.S. Discovery Map).
Type specimens
None designated; status of original material uncertain.
Type locality
None designated, original material described from 24°N-65°S in the Indian and Atlantic Oceans.