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(Brady and Norman, 1896)

Marked sexual dimorphism in size [C.haddoni-fem-lat; C.haddoni-male-lat]. Female carapace large, strongly tapered with maximum height about three quarters the length. The postero-dorsal corner right-angled, lacking spines. The posterior margin curves smoothly into ventral margin. The male carapace is not so strongly tapered and is relatively broader [C.haddoni-fem-vent; C.haddoni-male-vent]. In both sexes left asymmetrical gland opening close to the postero-dorsal corner, and right asymmetrical gland at about a third height on posterior margin.
Female, frontal organ clearly differentiated, capitulum finely spinous almost all over [C.haddoni-1]. First antenna, sensory setae short, less than half the length of the "e" seta. Second antenna endopodite [C.haddoni-2], second podomere carrying a "c" seta, which is as long as the podomere - a feature typical of the bispinosa group (i.e., Claus' genus Orthoconchoecia).
Male, frontal organ capitulum down-turned, recurves anteriorly near tip [C.haddoni-3]. First antenna "e" seta with double row of small stout spines becoming longer and thinner basally; 37- 42 spines in each row paired or arranged independently [C.haddoni-4]. Second antenna endopodite with long "c" and "d" setae on the second podomere [C.haddoni-5].

Female 2.7-3.2 mm, male 2.2-2.6 mm carapace length.

Depth range
Typically mesopelagic.

Distribution in the North Sea
Northern North Sea.

World distribution
Reported from all oceans; 60°N-51°S in the Atlantic, where it may also occur >60°N according to Poulsen (1977). The large form seems to be bipolar with smaller races occurring at low latitudes.

According to recent taxonomic revision, the species haddoni is placed in the genus Orthoconchoecia (M.V. Angel, pers. com.). However, for technical reasons, the former generic name Conchoecia had to be remained in the multimedia files.

[After Angel, 2000]

Orthoconchoecia haddoni