In lateral aspect carapace shape similar to C. magna (Conchoecia magna) except the posterior margin in females is more arcuate (C. subarcuata Habitus 1, C. subarcuata Habitus 3). Left asymmetrical gland opening at the hind end of the hinge, the right asymmetrical gland exceptionally broad in outline, opening at the postero-ventral corner. In both sexes, breadth <40% length (i.e., much slimmer than C. magna (C. subarcuata Habitus 2, C. subarcuata Habitus 4). Sides of the rostra taper in ventral aspect.
Female, frontal organ capitulum, down-turned about 45°, spinose, ending in a curving point (C. subarcuata 1). First antenna with long dorsal seta, "a"-"d" setae about 40% of "e" seta.
Male, frontal organ capitulum down-turned, hirsute, and blunt-ended (C. subarcuata 3). First antenna, "a" seta longer than second podomere, "c" seta short, "b" and "d" setae are subequal, just shorter than "e" seta, "e" seta armature about 27 pairs of long basally-pointing spines (C. subarcuata 4). Second antenna endopodite, "b" seta with a tuft of long hairs at midpoint, right-hand hook appendage with basal angle of 135°, with beyond a straight shaft leading to a further curve of about 45°, ending in a ridged point (C. subarcuata 5).
Superficially most similar to C. magna (Conchoecia magna), but readily distinguished on the basis of the width of the right asymmetrical gland, the relative slimness of the carapace in ventral aspect, the regular spacing and shape of the spines in the "e" seta armature, and the structure of the right hook appendage.
Recorded from all oceans and in the Atlantic from 60°N-56°S. This is a shallow mesopelagic species most abundant at 200-500m. 1, 2, 3 (R.R.S. Discovery Map).
None designated; status of original material uncertain.
Original description based on material collected in the North Atlantic at 37°45'N 13°38'W near Funchal and 32°30'N 16°42'W.