Sars, 1900
Short Description:
Pseudochirella spectabilis is an aetideid calanoid copepod known after both sexes (female 7.17- about 8 mm in length and male 6.00-6.66 mm in length). Bipolar species, of epi- and mesopelagic.
Taxonomic Description:
Female. Total length 7.17, about 8 mm. Cephalothorax 3.4-4.5 times longer than abdomen. Th5 posterior corners prolonged into lobes ending in small spine, they are asymmetrical. Genital segment asymmetrical, in its posterior half it is more widened, projection on the right is more developed than that on the left, variable in shape. A1 equal to cephalothorax, or reaching the midlength of abdomen. Re1 A2 without setae, Re2 A2 with the distal setae only; Ri1 A2 with 1 seta. Ri1 Md with 2 setae, Ri2 Md with 9 terminal and 2 posterior setae. Mx1 third internal lobe with 4 setae and appendage. Mx2, Mxp typical of the genus. Re P1 3-segmented, but separation between Re1 and Re2 incomplete. Ri P2 2-segmented. P4 coxopodite with 8-12 spines and on the left leg they are weaker than on the right.
Male. Total length 6.00-6.66 mm. Cephalothorax about 3 times longer than abdomen. Cephalon and Th1, as well as Th4-Th5 fused. Th5 posterior corners with small spine. A1 reaching the midlength of abdomen. Oral parts in comparison with that in female reduced. Re P1 3-segmented, external spine on Re1 shorter than in female. P5 powerful, configuration of segments is changing in dependance of position of leg.
Remarks. Sars (Sars, 1900) never recorded the asymmetry of Th5 posterior corners and genital segment. However, the studied type specimen of Undeuchaeta spectabilis Sars, 1900 (F 2449 deposited in the Zoological Museum of Oslo University) has genital segment and Th5 asymmetrical and identical in structure to that in P. elongata (Wolfenden, 1905). Thus my previous assumption concerning the identity between P. elongata (Wolfenden, 1905) and P. spectabilis (Sars, 1900) was confirmed, and the former species should be considered the junior synonym of P. spectabilis (Sars, 1900).
Vertical distribution:
Probably mesopelagic species, single findings are known in epipelagic (Sars, 1900; Bjornberg, 1973; Markhaseva, 1996); was found in epipelagic of Arctic Basin under T 1.6°C (Markhaseva, 1996). Recorded in hauls between 500 and 750 m (Vervoort, 1957), 200-750 m and 750-bottom (Markhaseva, 1996), also in total hauls from depths 3000 m (Wolfenden, 1911; Park, 1978).
Geographical distribution:
Bipolar species, distributed circumpolar in Arctic, Antarctic and Subantarctic (Sars, 1900; Wolfenden, 1905, 1911; Brodsky, 1950; Brodsky and Nikitin, 1955; Vervoort, 1957; Minoda, 1967; Park, 1978; Markhaseva, 1989). Species was found in the Bering Sea (Minoda, 1971; Motoda and Minoda, 1974) but very possible that this finding in reality is P. accepta.
Type locality: central part of the Arctic Basin (in the region off 84°N).
Material examined:
103 females and 6 males from samples: 267, 270-272, 276, 278, 281-283, 285, 289, 291, 293, 296, 297, 302, 304, 306, 335-338, 344, 376, 378, 379, 393, 429, 470, 483, 487, 490, 492, 500, 501, 507, 524, 544, 545, 547, 554. See examined samples module.