биота российских вод японского моря - Materials of Alexey Shipunov

The family Euphausiidae comprises ten genera. Ten species of five genera (Euphausia,Thysanoessa, Pseudeuphausia, Nematoscelis, and Stylocheiron) occur in theSea of Japan (Ponomarjeva, 1963; Araki, 1971; Lomakina, 1978; Pogodin, 1981).Four species belonging to two genera were found in the Russian waters of the Sea ofJapan, namely: Euphausia pacifica, Thysanoessa inermis, T. raschii, and T. longipes.Finds of two more species, Euphausia similis and Thysanoessa inspinata (Adrianov &Kussakin, 1998) have not been proved by our data.KEY TO THE GENERA OF THE FAMILY EUPHAUSIIDAE1(2). Exopod of thoracopod 7 well developed, but short. (Frontal plate of rostrum welldeveloped) ......................................................................... 1. Thysanoessa (p. 83)2(1). Exopod of thoracopod 7 rudimentary, in shape of small one-segmented setaceousplate. (Frontal plate of rostrum absent) ................................ 2. Euphausia (p. 86)Genus Thysanoessa Brandt, 1851Type species: Thysanoessa longipes Brandt, 1851.Frontal plate of rostrum long, narrow, sharply pointed. Carapace with keel runningfrom its middle to anterior region. Eyes with (bilobed) or without constriction,rounded; bilobed eyes pyriform; upper lobe narrower than lower one. Thoracopods 1–6 with full complement of normally developed segments. Species with bilobed eyeshave long inflated endopods of thoracopods 2, thus modifying this pair of limbs intograsping organs. Thoracopod 7 with normally developed, but short exopod; endopodof this thoracopod consists of 1–2 segments in females and absent in males. Thoracopod8 rudimentary, consisting only of small, thin 1–2 segmented exopod.Three species of ten comprising this genus occur in the Sea of Japan.KEY TO THE SPECIES OF THE GENUS THYSANOESSA1(4). Tergites of abdomen smooth, without sharp keels. (Posterior margin of one ortwo terminal segments of abdomen occasionally with small spine).2(3). Lower margin of carapace without spine. Posterior margin of tergite of abdominalsegment 6 and sometimes also segment 5 with small spine. Eyes without constriction,in juveniles usually with constriction in upper anterior part ................................................................................................................... 1. T. inermis (p. 84)3(2). Lower margin of carapace with anterior spine. Tergites of all abdominal segmentssmooth, without spines. Faceted part of eye round, without constriction................................................................................................. 2. T. raschii (p. 85)4(1). Tergites of abdominal segments 3–5 with keels ending in spines. (Eyes bilobed,pyriform, constriction transverse, upper lobe narrower than lower one. Posteriormargin of each abdominal segment 3–5 with spine. Lower part of carapace withmedian spine) ....................................................................... 3. T. longipes (p. 85)83