Carapace with well developed, sharp-edged shoulder vaults, height about 50% of length, tapers anteriorly (C. spinifera Habitus 1, C. spinifera Habitus 3). At postero-dorsal corner, right valve with primary and secondary spines. Left asymmetrical gland opening at this corner. Right asymmetrical gland opening at the postero-ventral corner. Sculpturing, two to four longitudinal striae running parallel to and close to the ventral margin for much of its length. In some males the ventral margins and the shoulder vaults appear darkly opaque under transmitted light, possibly because of accumulated secretions in the bioluminescent glands lining these margins.
Female, frontal organ well differentiated, stem longer than first antenna, capitulum slightly down-turned, with ventral margin swollen for much of its length, end pointed (C. spinifera 1). First antenna clearly segmented, second podomere with long dorsal seta reaching to mid-length of capitulum; "a"-"d" setae are 40% of "e" seta, the latter with a fringe of long hairs along basal half of anterior edge.
Male, frontal organ, capitulum down-turned, bluntly pointed and bare (C. spinifera 3). First antenna with convoluted "a" seta equal in length to limb, "c" seta short, "b" and "d" setae are subequal, only just shorter than "e" seta, "e" seta armature 28-30 pairs of basally pointing spines with a few distally pointing spines at the distal end (C. spinifera 4). Second antenna endopodite, right-hand hook appendage with inner barb, a basal right angle then, a smooth curve to end in a small ridged swelling (C. spinifera 5).
At low latitudes, the commonest species with sharp-edged shoulder vaults, but at temperate and higher latitudes C. borealis (Conchoecia borealis)is more common. Adults of C. spinifera are extensive diel vertical migrants, being, by day, at depths >400m, migrating up into the epipelagic zone at night. Poulsen, 1973 attributed it to his genus Paraconchoecia , along with 22 others, stating "the main character for this genus, and in fact the only one connecting all its species and not found in any other genera, is the shape of the masticatory pad of the endite of the mandible". Martens, 1979 pointed out that the genus remains, strictly-speaking, a nomen nudum until a type species is designated; clearly, if this genus is to be adopted, the type species should be selected from one of the original four included by Claus, 1891 i.e., C. oblonga (Conchoecia oblonga), C. spinifera , C. inermis (Conchoecia inermis) and C. elegans (Conchoecia elegans). Most authors would now separate C. elegans from the others.
Recorded from all oceans. From 60°N-42°S in the Atlantic. Generally mesopelagic to epipelagic in its bathymetric range. 1, 2, 3 (R.R.S. Discovery Map).
None designated; status of original material uncertain.
Original material collected in the North Atlantic 34°18'N 15°34'W, and from the Mediterranean Sea in the vicinity of Capri.