биота российских вод японского моря - Materials of Alexey Shipunov

Description. Antennal scale 4.3–9.4 times as long as broad. Carpo-propodus ofthoracopods 2–8 consists of 3 to 5 subjoints (in northwestern Pacific mysids, usuallyof 3 segments). Exopod of pleopod 3 of male 1.5–2.3 times longer than endopod. Exopodof pleopod 4 of male 3.7–7.8 times longer than endopod; basal segment slightlylonger than all other segments of exopod together with terminal seta. Inner margin ofendopod of uropod bears row of 20 to 56 spines, extending from statocyst almost toapex. Telson with relatively broadly rounded apex, 2.0–2.75 times as long as broad atbase. Lateral margin of telson covered with numerous (38–73) spines, gradually increasingin length towards apex, or gathered in indistinct groups. Apex of telsonarmed with 2 pairs of spines, outer one 1.5–3 times longer than inner one. Maximumlength of females 39.9 mm, of males 41.2 mm.Distribution. S. grandis is an amphiboreal-arctic species. It is found in the PacificOcean and the adjacent Arctic regions from British Columbia, the Tatar Strait andIturup Island of the Kurils (crosspiece of Kasatka Bay) to the Chukchi Sea (67°20.9′N,164°58.4′W). In the North Atlantic and in the Arctic it occurs from Labrador Peninsulaand northern Norway to the western coast of the Novaya Zemlya Archipelago andthe border between the Krasnaya Armiya Strait (Severnaya Zemlya Archipelago) andthe Laptev Sea. The species is found in the Sea of Japan in the Tatar Strait: from MoneronIsland (46°08.2′N) to 49°40′N.Habitat and breeding. S. grandis is a sublittoral-upper bathyal species. Its depthrange is from 0 to 402 m, predominantly from 25 to 200 m; in the Sea of Japan recordedat depths from 89 to 175 m. It occurs in waters with a temperature from -1.8° to+8.1°C and a salinity of 30 to 35‰ over sandy or silty bottoms, rarer over stony bottoms.There are no records for the breeding of this species in the Sea of Japan.Remarks. Stilomysis major Tattersall, 1951 from the southern part of the Sea ofJapan is closely related to S. grandis, differing from it in the more elongate antennalscale (10 times as long as broad) having very narrowly rounded apex, and in the morenarrowly rounded apex of the telson: the ratio of the telson width at the apex to thesame at the base is 1/30–1/20 (in S. grandis 1/6–1/10); the lateral margin of the telsonis armed with up to 84 spines. There is one more related species, S. camtschatica Marukawa,1928, but it is likely to be a dwarf form of S. grandis.4. Genus Disacanthomysis Holmquist, 1981Type species: Orientomysis dybowskii Derjavin, 1913.Eye large, stalk trapezoid. Antennal scale elongate, 2-segmented, with setae allalong margin. Labrum with long, sharp anterior process. Female marsupiums composedof 2 pairs of well-developed oostegites. All male pleopods except for pair 4 andall female pleopods rudimentary, plate-shaped, relatively short, except for pleopods 5in males. Male pleopod 5 elongate, slightly shorter than pleopod 4, with row of lateralsetae and strong, long terminal seta. Male pleopod 4 biramous with one-segmentedendopod, about as long as 1/2 of 3-segmented exopod; basal segment of exopod longest;distal segment very small: approximate ratio of lengths of segments 23:5:1. Eachsegment of exopod armed with 1–2 simple distal setae; distal segment additionallywith two strong plumose setae. Endopod of uropod with row of spines on small lobe atinner ventral margin near statocyst. Telson linguiform; lateral spines situated on itsdistal third, gathered in distinct groups; rounded apex bears 2 pairs of spines.There is one species in the genus.53