イボダイ科 Centrolophidae Butterfishes, Medusafishes,
Warehous
40 ナンキョクメダイ
Hyperoglyphe antarctica
(
Specimens
examined: 3 (
Counts:
D IX, 19–20; A III, 14–15; P1 20–21; P2 I, 5; GR 5–7+17=22–24;
LLS 84–90; V 10+15=25. Measurements:
head length 30.7–31.5% SL; body depth 33.4–34.3% SL; dorsal-fin-base length
48.5–50.6% SL; anal-fin-base length 19.3–22.3% SL; predorsal
length 35.0–36.5% SL; pre-anus length 59.4–62.2% SL; pectoral-fin length
28.3–31.8% SL; pelvic-fin length 15.7–16.4% SL; caudal-peduncle depth 8.4–9.3%
SL; caudal-peduncle length 16.9–17.0% SL; eye diameter 18.1–19.7% HL; interorbital width 39.8–41.7% HL; snout length 27.2–32.0%
HL; upper-jaw length 43.5–46.6% HL.
計数形質：背鰭9棘，19–20軟条；臀鰭3棘，14–15軟条；胸鰭20–21軟条；腹鰭1棘，5軟条；鰓耙数5–7+17=22–24；側線鱗数 84–90；脊椎骨数10+15=25．計測形質：頭長30.7–31.5%
SL；体高33.4–34.3%
SL；背鰭基底長48.5–50.6%
SL；臀鰭基底長19.3–22.3%
SL；背鰭前長35.0–36.5%
SL；肛門前長59.4–62.2%
SL；胸鰭長28.3–31.8%
SL；腹鰭長15.7–16.4%
SL；尾柄高8.4–9.3%
SL；尾柄長16.9–17.0%
SL；眼径18.1–19.7%
HL；両眼間隔39.8–41.7%
HL；吻長27.2–32.0%
HL；上顎長43.5–46.6%
HL.
特 徴 体は長卵形で，側扁する．吻端は丸く，吻長は眼径よりも長い．口はやや大きく，上顎後端は眼の中央直下に達する．両顎には微少な円錐歯が1列に並ぶ．鋤骨，口蓋骨および舌上に歯はない．背鰭始部は胸鰭基部の直上に位置する．背鰭棘条は短く，鰭膜で連続する．背鰭の棘条部と軟条部の間に切れ込みがある．胸鰭は鎌形で長く，後端は肛門の直上に達する．腹鰭は短く，その基部は胸鰭基部の直下付近に位置する．尾鰭は深く二叉する．鱗は小さい円鱗で，剥がれやすく，背鰭と臀鰭の基部をも覆う．眼の上方にパッチ状の鱗の集まりがある．食道嚢をもつ．頭部と体側の背部は青紫，体側の腹部は銀白色．背鰭と胸鰭は青みがかった茶色，尾鰭，臀鰭および腹鰭は茶色．
分 布 大西洋南東部，南インド洋，太平洋南西部（オーストラリア南部，ニュージーランド），南アフリカ（Parin
and Piotrovsky, 2004）．
備 考 本種はミナミクロメダイSchedophilus velaini
(Sauvage, 1879)に外見が類似するが，本種の方が背鰭と臀鰭の鰭条数がともに少なく（背鰭VIII–IX,
19–22 vs. VI–VIII, 25–29；臀鰭III, 14–16 vs. III,
19–20），眼の上方に鱗の集まりがあること（ミナミクロメダイにはない），背鰭の棘条部と軟条部の間に切れ込みがあること（ミナミクロメダイでは切れ込みがない），強い背鰭棘が明瞭に見分けられること（ミナミクロメダイでは弱い棘が皮膚に埋もれる）によって異なる．本種の稚魚はオーストラリアとニュージーランド海域において表層付近の漂流物や流れ藻の下から採集されており，体長約70–90
mmで体側に淡色の不定型な斑紋をもつことによって特徴づけられる（Last
et al., 1993; Duffy et al., 2000）．本種はトロールおよび延縄漁業の対象魚種である．
（岡本）
Description Body
oval and laterally compressed. Snout round, its length longer than eye
diameter. Mouth moderately large, posterior end of maxilla reaching below
center of eye. A single row of minute conical teeth on both jaws. Vomer, palatine, and tongue lacking teeth. Dorsal-fin
origin located above pectoral-fin base. Dorsal-fin
spines short, connected by fin membrane. A notch present between spinous and soft-rayed parts of dorsal fin. Pectoral fin long,
falcate, its posterior end reaching to above anus. Pelvic fin short, its base
closely situated below pectoral-fin base. Caudal fin deeply forked. Scales
small and cycloid, deciduous, extending to cover bases of dorsal and anal fins.
Scales present above eye, forming a small patch. Pharyngeal sac present. Head and dorsolateral body
bluish purple, and ventrolateral body silvery white.
Dorsal and pectoral fins brown tinged with blue, and caudal, anal, and pelvic
fins brown.
Distribution Southeastern
Atlantic, South Indian, and Southwestern Pacific (southern
Remarks This
species is similar to Schedophilus velaini (Sauvage, 1879) in general appearance, but differs from the latter
in having fewer dorsal- and anal-fin rays (D VIII–IX, 19–22 vs. VI–VIII, 25–29
and A III, 14–16 vs. III, 19–20), a small patch of scales above the eye (vs.
absent in S. velaini),
a notch of the dorsal fin between spinous and
soft-rayed parts (vs. notch is absent in S.
velaini), and the strong dorsal-fin spines
distinctly noticed (vs. weak dorsal-fin spines buried in the skin in S. velaini).
Juveniles of this species were collected from beneath flotsam or drift algae
near the surface in Australian and
(M.
Okamoto)