Wolfenden, 1905
Short Description:
Pseudochirella hirsuta is an aetideid calanoid copepod known after both sexes (female 8.50-9.41 mm and male 7.20 mm in length) from Antarctic and the Pacific Ocean, mainly meso-bathypelagic.
Taxonomic Description:
Female. Total length 8.50-9.41 mm. Cephalothorax 4.0-4.2 times longer than abdomen. Cephalon is narrower in its anterior part, unclearly separated with Th1. Th4-Th5 virtually completely fused. Posterior Th5 corners symmetrical, when looking laterally of smooth triangular shape, covering nearly one third of genital segment length; they are supplied with hairs in present specimens. When looking dorsally Th5 posterior corners with somewhat bifid tops. Genital segment symmetrically widened in its middle length (dorsal view), ventral swelling not prominent. Abd1-3 surface with hairs. A1 by 1-2 last segments longer than body. Ri1 A2 with 2 setae; Re1 A2 with 1 seta, Re2 A2 with 2 medial and 1 distal seta. Ri1 Md with 2, Ri2 Md with 9 long terminal and 2 posterior setae. Second Mx1 internal lobe with 4 setae and appendage. Mxp protopodite with knob in its proximal third part, well visible from different angles. Mx2 typical of the genus. Re P1 3-segmented. Ri P2 2-segmented. P4 coxopodite with 15 (after Park (1978) with 10-13) robust spines.
Male. Total length 7.20 mm. Cephalothorax 3.4 times longer than abdomen. Cephalon and Th1, as well as Th4-Th5 fused. A1 reaching nearly Abd2. Oral parts reduced in comparison with that in female. Re P1 3-segmented, external spine on Re1 is very small. General type of P5 structure is typical of the males of Pseudochirella , on Re2 P5 left one tooth present, Re3 P5 left is nearly 4 times longer than wide.
Vertical distribution:
Probably meso-bathypelagic species; found in haul 1000-2000 m (Hardy and Gunther, 1935), hauls 350-1786 and 350-2394 m (Grice and Hulsemann, 1967), found in total hauls from depths 400-3000 m (Markhaseva, 1996), recorded from total hauls from depths 600-5000 m (Wolfenden, 1911; Farran, 1929; Vervoort, 1957; Bjornberg, 1973; Park, 1978).
Geographical distribution:
The species occurs circumpolar in Antarctic and Subantarctic, may be characterized as subantarctic-antarctic species. Pacific Ocean: to the North to 30°S along the coast of South America (Bjornberg, 1973; Grice and Hulsemann, 1968; Markhaseva, 1996), also recorded in the region of 39-42°S 130-144°W (Markhaseva, 1996); in the Indian Ocean known from the region off 30°S 66°E (Grice and Hulsemann, 1967; Markhaseva, 1996), the most northern locality in the Atlantic Ocean - region of 35°S (Wolfenden, 1911). The northernmost findings of species in the Indian and Atlantic oceans, probably may be explained by the fact that the species is transported out with meridional water currents from Subantarctic, i.e. the latter localities, do not belong to the distribution area proper, but to the zone of species eviction.
Type locality: South Atlantic: region of 35°S and 2-8°E.
Material examined:
140 females and 11 males from samples: 266, 268, 269, 272, 274, 275, 285, 290, 296, 299, 307, 309, 312, 313, 316-320, 322-325, 327, 329-332, 334, 338-342, 346-348, 353, 354, 358, 363, 364, 370, 372-376, 379, 383, 395, 434. See examined samples module.