Claus, 1890
Description
Carapace with well developed, sharp-edged shoulder vaults, height about 50% of length, tapers anteriorly [C.spinifera-fem-lat; C.spinifera-male-lat]. 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].
Size
Female 1.86-2.2 mm, male 1.6-1.84 mm carapace length.
Depth range
Generally mesopelagic to epipelagic.
Distribution in the North Sea
No information available.
World distribution
Recorded from all oceans. From 60°N-42°S in the Atlantic.
Remarks
According to recent taxonomic revision, the species spinifera is placed in the genus Paraconchoecia (M.V. Angel, pers. com.). However, for technical reasons the former generic name Conchoecia had to be maintained in the multimedia files.
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 >400 m, 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, C. spinifera, C. inermis and C. elegans [Conchoecia elegans]. Most authors would now separate C. elegans from the others.
[After Angel, 2000]