Markhaseva, 1989
Short Description:
Pseudochirella tanakai is an aetideid calanoid copepod known after both sexes (female 5.70-6.45 mm and male 5.51 mm in length) from the north-western part of the Pacific Ocean, of mostly bahtypelagial.
Taxonomic Description:
Female. Total length 5.70-6.45 mm. Cephalothorax about 3.8-4.4 times longer than abdomen. Th5 posterior corners rounded and symmetrical. Genital segment with projections on the right and on the left, slightly asymmetrical, forming type of shoulders of the segment. A1 reaching nearly the midlength of abdomen, or about same length as body. Re1 A2 with 1 small seta, Re2 A2 with 1 distal seta. Ri1 A2 with 1 seta. Ri1 Md with 2, Ri2 Md with 9 terminal and 1 posterior setae. Mx1, Mx2, Mxp typical of the genus. Re P1 incompletely 3-segmented. P2 indistinctly 2-segmented. P4 coxopodite with 4-7 spines.
Male. (Description after Tanaka and Omori (1969b) with modifications). Total length 5.51 mm. Cephalothorax about 3 times longer than abdomen. Cephalon and Th1, as well as Th4-Th5 fused. Th5 posterior corners rounded, spines absent. A1 reaching distal border of Abd2. Re and Ri A2 equal in length. Ri2 A2 with 6 long setae on external lobe and 7 long and 1 small setae on internal lobe. Mx1 with 7 setae on external lobe, Re with 11 setae, Ri with 13, protopodite near Ri base with 5 setae, third internal lobe with 4, second with 2 reduced setae and 7 reduced setae on gnathobase. Re P1 3-segmented, spine on Re1 P1 very small. Left Re2 P5 with 1 tooth on distal border.
Remarks. The present male was described by Tanaka and Omori (1969b) under the name Pseudochirella pustulifera (Sars) together with female that was later considered independent species P. tanakai (Markhaseva, 1989). However the status of the male is still doubtful.
Vertical distribution:
Bathypelagic species. Found in 2 hauls between 1000 and 2000 m (Markhaseva, 1996), also known from total hauls from depths of 7000 m (Tanaka and Omori, 1969; Markhaseva, 1996).
Geographical distribution:
The region of the Kurile-Kamchatka Trench (Markhaseva, 1996) and from the Izu region (Tanaka and Omori, 1969b).
Type locality: the Kurile-Kamchatka Trench area (Markhaseva, 1989).
Material examined:
5 females from samples: 48, 70, 127, 134-137, 174. See examined samples module.
Holotype: 1 female, N 1/66280, kept in the Zoological Institute, Russian Academy of Sciences, R/V "Vitjaz", 39 cruise; the Kurile-Kamchatka Trench, 45°48'N 153°33'E; station 5617; sample 117, 5-6.08.1966, total haul from 7040 m, ring-trawl. 4 females, paratypes all taken in 22 cruise of "Vitjaz": N 2/66281, 28°08'N 141°07'E, 22.10.1955, station 3515, sample 734, total haul from 4400 m; also females taken in 39 cruise of R/V "Vitjaz": N 3/66282, 46°04'N 153°22'E, station 5607, sample 41, 19.07.1966, total haul from 5000 m; 4/66283, 45°06'N 155°54'E, station 5621, samples 149-151, 17.08.1966, sample range 2790-806 m; 5/66284, 43°52'N 149°49'E, station 58, sample 214, 30.08.1966, sample range 2130-1540 m (3 latter stations accomplished in Kurile-Kamchatka Trench area).