Carapace, lateral aspect sub-rectangular with slight anterior taper, in both sexes height <40% length (C. inermis Habitus 1, C. inermis Habitus 3). The postero-dorsal corner a rounded right-angle on both valves. Right asymmetrical gland opening at posteroventral corner and the left at the postero-dorsal corner just ventral to the end of the hinge. Carapace free of sculpture.
Female, frontal organ stem 30% longer than first antenna, capitulum is downturned, finely hirsute and swollen terminally (C. inermis 1). First antenna with dorsal seta extending just beyond the base of the capitulum; sensory setae about 45% the "e" seta length; "e" seta with fringe of long hairs on its anterior edge.
Male, frontal organ stem equal in length to first antenna; capitulum slightly down-turned, bare and round ended (C. inermis 3). First antenna "a" seta S-shaped at base and equal in length to the second podomere; "c" seta is half that length; "b" and "d" setae sub-equal, slightly shorter than the "e" seta; the "e" seta armature a brush of long hairs rather than spines (C. inermis 4), distal of the armature the "e" seta is angled leading to a short terminal length. Right-hand second antenna endopodite with hook appendage with short basal arm before bending through about 100°, distally it bends through a further 45°(C. inermis 5).
This species has been considered to be closely related to C. oblonga (Conchoecia oblonga) and C. spinifera (Conchoecia spinifera) on the basis of the structure of its mandibular endite and the fringe of long hairs on the anterior edge of the "e" seta of the first antenna in the female. The armature of the male "e" seta consisting of hairs rather than spines suggests a possible relationship with C. mamillata (Conchoecia mamillata) or even C. elegans (Conchoecia elegans).
Recorded from all oceans. It always appears to be a non-migrant in the North Atlantic and has a restricted bathymetric range in the mesopelagic. 53°N-13°30'S in Atlantic. 1, 2 (R.R.S. Discovery Map).
None designated; status of original material uncertain.
Original description based on material collected at 34°18'N 15°34'W in the North Atlantic.