Wolfenden, 1911
Short Description:
Chiridius polaris is an aetideid calanoid copepod known after both sexes (female 3.30-4.25 mm and male 3.55-3.80 mm in length) mostly from bathy- and abyssopelagic. Bipolar species.
Taxonomic Description:
Female. Total length 3.30-4.25 mm. Cephalothorax 2.9-3.6 times longer than abdomen. Posterior points of Th5 corners cover, as a rule, first third of genital segment, sometimes reaching its middle, even exceeding its middle. When looking dorsally they are straight, rarely converging, sometimes slightly divergent. Genital segment is the widest in the second third of its length, or between first and second thirds. A1 reaching the midlength of genital segment, or the midlength of Abd2. Ri2 Md with 7 long, strong setae and 1 small, thin posterior seta. Re Mx1 with 10 setae. External spines on Re1 and Re2 P1 exceeding the base of following spine. Ratio of external spine on Re3 P1 to external spine on Re2 P1 is (1.04-1.26):1. P2 with 3-segmented Re and 2-segmented Ri, segmentation of Ri not always complete. First and second external spines on Re3 P2 usually long, reaching, or exceeding the base of following spines. P3-P4 rami 3-segmented (sometimes with incomplete separation of first and second segments of Re and Ri. External spines on Re3 P3 shorter and thinner than on P2, not reaching the base of following spine, such spines on P4 are thinner.
Male. Total length 3.55-3.80 mm. Cephalothorax 2.5-2.9 times longer than abdomen. Posterior points of Th5 corners not longer than genital segment. A1 slightly shorter than cephalothorax. Ri2 Md with 8 long setae and 1 short seta. Third internal lobe of Mx1 with 2 setae, 3 setae are near the Ri base, 9 on the Ri, external lobe with 7 long and 2 short setae. First external spine on Re1 P1 exceeding the base of following spine. P2 with 2-segmented Ri, first and second external spines on Re3 as in female. P3 and P4 with 3-segmented rami. P5 uniramous.
Vertical distribution:
Probably belowbathypelagic-upperabyssopelagic species, in high latitudes it is more likely mesopelagic. It was found in hauls between 2000 and 4000 m in the region of the Kurile-Kamchatka Trench (Markhaseva, 1996), in Antarctic recorded in mesopelagic (Vervoort, 1957), in total hauls from mesopelagic (Farran, 1929; Markhaseva, 1996).
Geographical distribution:
Bipolar species; recorded circumpolar in Antarctic, found in Subantarctic; the most northern finding here: 49°19'S 120°19'W (Park, 1978) in the antarctic part of the Pacific Ocean, other findings are to the South from 60°S (66-69°S) (Farran, 1929; Vervoort, 1957). Species was also found in the region of the Kurile-Kamchatka Trench.
Type locality: to the south of 60°S in the Indo-oceanic sector of Antarctic (Wolfenden, 1911).
Material examined:
25 females and 4 males from samples: 18, 65, 67, 81, 85, 102, 140, 163, 175, 218, 277, 283, 286, 290(?), 292, 301, 302, 311, 344, 384, 430, 474. See examined samples module.