シマガツオ科 Bramidae Pomfrets
29 ニシシマガツオ
Brama brama
(Bonnaterre, 1788) Atlantic
Pomfret
Specimens
examined: 4 (SNFR 15934, 15935, 16604, 16605; 422–439
mm SL, 461–488 mm FL, 338–446 m depth.
Counts:
D 35–38; A 29–32; P1 21–23; P2
I, 5; GR 5–8+11–13=17–20; LS 79–85; V 16–17+26–27=43–44. Measurements:
head length 27.3–28.2% SL, 24.7–25.9% FL; body depth 47.4–49.0% SL, 42.9–44.8%
FL; eye diameter 22.5–23.5% HL; interorbital width 29.1–35.6%
HL; snout length 28.2–33.0% HL; upper-jaw length 50.6–53.5% HL; lower-jaw
length 50.9–54.9% HL; caudal-peduncle length 45.9–51.2% HL; caudal-peduncle
depth 22.2–23.5% HL; pectoral-fin length 38.9–42.1% SL, 35.2–38.6% FL;
pelvic-fin length 29.7–35.7% HL.
計数形質：35–38軟条；臀鰭29–32軟条；胸鰭21–23軟条；腹鰭1棘，5軟条；鰓耙数5–8+11–13=17–20；縦列鱗数79–85；脊椎骨数16–17+26–27=43–44．計測形質：頭長27.3–28.2%
SL, 24.7–25.9% FL；体高47.4–49.0%
SL, 42.9–44.8% FL；眼径22.5–23.5%
HL；両眼間隔29.1–35.6% HL；吻長28.2–33.0% HL；上顎長50.6–53.5%HL；下顎長50.9–54.9% HL；尾柄長45.9–51.2% SL；尾柄高22.2–23.5% HL；胸鰭長38.9–42.1% SL,
35.2–38.6% FL；腹鰭長29.7–35.7%
HL.
特 徴 頭部および体は側扁する．体は卵円形．尾柄部は細い．頭部背縁は強く弧を描く．吻部は鈍く，前部輪郭は垂直に近い．眼は楕円形で，上下に長い．下顎下面の内縁は互いに接し，峡部の前部は隠れる．上顎後端は眼の中央直下を超える．両顎歯は円錐歯で，下顎には数本の犬歯状歯がある．背鰭および臀鰭の前部は顕著に伸長する．背鰭および臀鰭は鱗に覆われ，倒せない．尾鰭は深く湾入する．胸鰭は長く尖り，頭長の約1.5倍．腹鰭は短い．鰓耙は細長く，扁平．最長の鰓弁は頭長の16–19%．側線は前部でゆるく湾曲し，後部で直線状；個体により部分的に不明瞭．鱗に棘がない（成魚）．体側中央の鱗は上下に長い．体および鰭は暗褐色．
分 布 地中海を含む北大西洋の広域，インド洋，南太平洋 (Haedrich, 1986; Last and Moteki,
2001)．
備 考 インド洋南西部には，本種と同じくシマガツオ属 BramaのヒメシマガツオBrama dussumieri
Cuvier, 1831，マルバラシマガツオBrama orcini
Cuvier, 1831，およびB. australis
Valenciennes, 1840 が分布する (Last
and Moteki, 2001)．本種は，ヒメシマガツオおよびマルバラシマガツオとは，臀鰭前部が明瞭に伸長すること（後者2種では不明瞭），B. australis
とは頭部の背縁が強い弧（B. australis
では緩やかな弧）を描くこと，臀鰭軟条数が多いこと（通常30以上 vs.
通常29以下）で区別できる．縦列鱗数は，本標本（79–85）およびニュージーランド産の標本 (78–91:
Yatsu, 1990) では北大西洋産の標本 (70–81:
Moteki et al.
1995) より多い．この違いは地理的変異と考えられる．
(星野)
Description
Head
and body compressed. Body oval. Caudal peduncle narrow. Dorsal profile of head
strongly arched. Snout blunt, its anterior profile nearly vertical. Eye
elliptical, vertically elongated. Inner lower edges of lower jaw contiguous,
concealing anterior portion of isthmus. Upper jaw extending posteriorly
beyond a vertical through mid-eye. Teeth of both jaws mostly conical; a few canines
in lower jaw. Anterior part of dorsal and anal fins elongate, forming a
distinct lobe. Dorsal and anal fins totally covered with scales, and not
depressible. Caudal fin deeply emarginate. Pectoral
fin long, pointed, about 1.5 times HL. Pelvic fin short. Gill rakers slender, flattened. Longest gill filament 16–19% HL.
Lateral line gently arched anteriorly, straight posteriorly; sometimes partly indistinct. Scales without
spines (in adults), those on center of body vertically elongated. Body and fins
dark brown.
Distribution
Widespread
in North Atlantic (including Mediterranean), Indian and
Remarks
Brama dussumieri Cuvier,
1831, Brama orcini Cuvier, 1831, and Brama australis
(K. Hoshino)