Chiridius obtusifrons

Chiridius obtusifrons G. O. Sars, 1902

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Description

Diagnostic Description

Endopodite of P2 one-segmented. Abdomen longer than 1/3 of cephalothorax. Posterior corners of the last thoracic segment short, divergent. Spermatheca much smaller than in other species of the genus. Male with uniramous P5, the right is longer than the left.

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Morphology

Female: Cephalothorax with widened front third, head fused with thorax, rounded from side view. Posterior corners of the last thoracic segment short, divergent, end before the middle of genital segment. Abdomen is 2.3-2 times shorter cephalothorax, the genital segment is slightly shorter than the combined length of the next 2 segments. Ventral projection very slight. The back edges of the first three segments with serrations. A1 reach the middle of the second abdominal segment. Endopodite of A2 almost 2 times shorter than the exopodite. The outer edge of the second basipodite of P1 with a small spine. Posterior corners of the last thoracic segment. Apical spines of exopodites of P1-P4 coarsely and sharply serrated.

Male: Smaller than female. P5 with no signs of endopodites, each leg five-segmented. A1 about as long as the cephalothorax.

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Size

Female: 3,50-4,60 mm
Male: 2,90-3,3 mm

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Ecology and Distribution

Distribution

Arctic species. Central Arctic Basin, North Sea, Norwegian Sea, Barents Sea, Laptev Sea, Greenland Sea, Chukchi Sea, Beaufort Sea, Gulf of Maine

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Habitat

Oceanic, epi-meso-bathypelagic species. In polar water found at small depths and near the surface, in lower latitudes at depths of 200-800 m.

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Reproduction

Produce egg-sacs with a thick enclosing membrane, which contains 25-50 bright orange eggs.

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Trophic Strategy

Opprotunistic omnivores; mainly feed phytoplankton and/or phytodetritus, but may also consume microzooplankton and copepod nauplii

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References

Brodsky, K. A. (1950).  Calanoida of the Far Eastern Seas and Polar Basin of the USSR. Opred. Fauna SSSR. 441. Leningrad: Publishing House of the USSR Academy of Sciences.
C., R., de F. B., J. K., & N. D. (2011).  Diversity and Geographic Distribution of Marine Planktonic Copepods.
Kosobokova, K., Hirche H. J., & Hopcroft R. R. (2007).  Reproductive biology of deep-water calanoid copepods from the Arctic Ocean. Marine Biology. Abstract