биота российских вод японского моря - Materials of Alexey Shipunov

2. Thysanoessa raschii (M. Sars, 1864)(Pl. I, fig. 2; II, figs. 2, 5)M. Sars, 1864: 83 (Thysanopoda raschii), G.O. Sars, 1883: 51 (Euphausia raschii);Hansen, 1911: 42; Lomakina, 1978: 185–187, fig. 114; Baker et al., 1990: p. 72, fig. 8a(Thysanoessa raschii).Description. Frontal plate of rostrum broad, slightly shorter than basal segmentof antennular peduncle; tip slightly blunt in males, pointed in females. Eyes round,without constriction. Lateral margin of carapace with small anterior spine. All thoracopodsidentical in arrangement. Abdominal segments smooth, without spines anddorsal keels.Euphausiids from northern part of Sea of Japan with maximum length of body29 mm (Pogodin, Gorbatenko, 1984).Distribution. T. raschii is a widespread boreal-arctic species. In the PacificOcean it occurs north of 40˚ N near the coasts of Asia and north of 45˚ N near theBritish Columbia. In the Atlantic Ocean it was found north of 40˚ N off the coasts ofAmerica and the northern coast of Great Britain. In the Arctic it is possibly circumpolar,found near the western coast of Greenland and from the Spitsbergen and the NorwegianSea eastward to the Beaufort Sea. In the Sea of Japan the species has not beenrecorded south of 43˚ N. In spring the population penetrates as far as the most northernpart of shallow-water area of the Tatar Strait.Habitat and breeding. T. raschii is a neritic, epipelagic species. It usually occursin depths to 200 m, more deep-water finds are rare. These euphausiids mainlyfeed on meso- and microzooplankton; in spring and autumn on phytoplankton; and, iffood is scarce, on detritus. In the population of the northern Tatar Strait the breedingprocess begins in April and proceeds till late July or even early August, depending onmean temperature of a year. Diameter of eggs 350–500 µm, perivitelline space narrow.3. Thysanoessa longipes Brandt, 1851(Pl. I, fig. 3; II, fig. 3; III, figs. 7–11)Brandt, 1851: 128; Lomakina, 1978: 176–178, fig. 106, 107; Baker et al., 1990: p. 68, fig.3b (Thysanoessa longipes); Marukawa, 1928: 4 (T. armata).Description. Frontal plate of rostrum long, narrow, with pointed tip and mediankeel, stretching to anterior region of carapace. Eyes with transverse constriction, upperlobe noticeably smaller. Lateral margin of carapace with spine placed slightly past itsmidpoint. Endopod of thoracopod 2 elongated, almost equal to antennule; its segment6 with lateral setae on both sides; segment 7 short and broad, with 4 strong setae. Eachtergite of abdominal segments 3–5 with well-expressed dorsal keel; keel on segment 3ends in robust spine; keels on other tergites with smaller spines. Tergite of abdominalsegment 6 without keel, its distal margin sometimes with small spine. Euphausiidsfrom northern part of Sea of Japan with maximum length of body 34 mm.Distribution. T. longipes is a Pacific widespread boreal species. It is distributednorth of 34°N near the Asian coast and north of 38°24′N near the American coast upto Point Barrow (Chukchi Sea). In the Sea of Japan the southern boundary of the distributionalarea stretches from the Korean coast (36–37°N) to Wakasa Bay (around85