Fragile deep-living species rarely caught in good condition, which is similar to C. dasyophthalma (Conchoecia dasyophthalma). It has well developed, sharp-edged shoulder vaults, the right asymmetrical gland opens at a notch well anterior of the postero-ventral corner, level with the posterior end of the shoulder vaults (C. mesadenia Habitus 1, C. mesadenia Habitus 3). Postero-dorsal corner rounded, and the posterior margin curves smoothly into the ventral margin.
Female, frontal organ partially differentiated, capitulum region slightly enlarged and finely hirsute (C. mesadenia 1). First antenna clearly segmented, second podomere carrying a long dorsal seta, "e" seta is over double the lengths of the sensory setae and carries a fringe of fine hairs distally of their ends. Second antenna endopodite both "f" and "g" setae are slightly sword-shaped terminally, "a" seta much shorter than the "b" seta (C. mesadenia 2).
Male, frontal organ stem is segmented and equals first antenna in length, capitulum slightly down-turned, hirsute on the basal two thirds of ventral surface, round ended (C. mesadenia 3). First antenna with convoluted "a" seta, "c" seta almost as long as the limb, "b" seta tapers sharply level with the distal end of the "e" seta armature where it carries a dense tuft of short hairs, "b" and "d" setae are subequal and only just shorter than the "e" seta, "e" seta armature a mixture of about 20 pairs of spines and fine hairs (C. mesadenia 4). Second antenna endopodite, right-hand hook appendage basally bent through a right angle then curves in a decreasing arc to end in a blunt ridged point, it also carries two barbs on the inner edge of its basal sector (C. mesadenia 5). The unbarbed left hook appendage bends through 135°.
Similar to C. dasyophthalma (Conchoecia dasyophthalma) and probably includes the material ascribed to that species by Chavtur, 1977 from the North Pacific.
Recorded only from the North Atlantic 20°N-50°N, but may also occur in the North Pacific. Bathymetric range abyssopelagic relatively common in benthopelagic samples from depths >2500m. 1 (R.R.S. Discovery Map).
Holotype a male dissected and mounted on slides, BM(NH) No 1984:164
44°14.3'N 13°42'W, Discovery Station 8509 haul 27; depth 3500-4000m; gear RMT1.