биота российских вод японского моря - Materials of Alexey Shipunov

6. Genus Boreoacanthomysis Fukuoka et Murano, 2004Type species: Mysis schrencki Czerniavsky, 1882.Carapace produced anteriorly into relatively short triangular rostral plate withalmost pointed or narrowly rounded apex. Eyes well developed, trapezoid, slightlydepressed dorsoventrally. Labrum with short anterior spiniform process. Antennalscale lanceolate, with rounded apex, armed with setae all along its outer and innermargins; subapical suture present. Marsupium composed of 2 pairs of well-developedoostegites. Tergites of free thoracic segments and all abdominal segments smooth,without transverse furrows or any transverse rows of spines and setae. First to thirdand fifth pleopods of male and all pleopods of female uniramous, reduced to unsegmentedplate, increasing in length from first to fifth; fifth pleopod of male not reachingmiddle of last abdominal segment. Fourth pleopod of male biramous; endopodreduced to unsegmented lobe; exopod long, almost straight, 2-segmented, proximalsegment long, armed on each distal corner with seta (occasionally without one or bothsetae); distal segment short, armed with 2 long, strong, subequal terminal setae andshort setae on distal corners (occasionally without one or both of these setae). Endopodof uropod armed with numerous, densely set spines on ventral surface near innermargin in statocyst region. Telson elongate, linguiform or triangular, with narrowapex; lateral margins armed on anterior 1/3–1/2 with almost equal spines set rathersparsely and on posterior 2/3–1/2 with grouped spines set densely, each group consistingof one large spine and one-three smaller ones; apex with 2 pairs of spines, outerspines much longer than inner ones.The genus comprises one species.1. Boreoacanthomysis schrencki (Czerniavsky, 1882)(Pl. XIII, figs. 1–4)Czerniavsky, 1882b: 20 (Mysis schrencki); Derjavin, 1913: 198 (Orientomysis schrencki);Ii, 1936: 589 (Acanthomysis schrencki); Holmquist, 1981b: 408 (Pacifacanthomysisschrencki); Fukuoka, Murano, 2004: 2137–2143 (Boreoacanthomysis schrencki).Description. Antennal scale 3.4–5.8 times as long as broad. Carpo-propodus ofendopod of thoracopods 5–8 consists of 3 (in juveniles) to 4–6 subjoints. Exopod offourth pleopod of male (with terminal setae) 3.0–4.0 times as long as endopod; basal(proximal) segment 3–6 times as long as distal one. Endopod of uropod armed with 6–8 (in juveniles) to 38 spines on ventral lobe placed near statocyst. Telson with slightlytruncated apex, 2.1–3.5 times as long as broad at base; inner spines on its apex 2–3times as short as outer ones. Maximum length of female body 18.5 mm, of male body14.6 mm.Distribution. B. schrencki is a West Pacific widespread boreal species. It is distributedfrom Possjet Bay (Sea of Japan) and the eastern coast of Hokkaido Island toParamushir Island (Kurils) and the northern coast of the Sea of Okhotsk. In the Sea ofJapan it occurs in Peter the Great Bay and in the Tatar Strait.Habitat and breeding. This is a sublittoral species, vertically distributed from 0to 80 m, mostly to 25 m. It occurs in waters with a temperature from -1.2° to +21.4°Cand a salinity between 29.5 and 34.3‰, predominantly over rocks and boulders orsandy silt, rarer over gravel with pebbles or silt. Females bearing embryos were rec-58