イボダイ科　Centrolophidae                  Butterfishes, Medusafishes, Warehous

 

41 ミナミクロメダイ

Schedophilus velaini (Sauvage, 1879)
Ocean Blue-eye Trevalla, Violet Warehou, African Barrelfish

 

Specimens examined: 5 (SNFR 16238, 16239, 16403, 16404, 16406; 412–488 mm SL), 360­–552 m depth.

Counts: D VI–VII, 25–29; A III, 19–20; P₁ 20–21; P₂ I, 5; GR 6–7+16–17=22–24; LLS 84–89; V 10+15=25. Measurements: head length 28.4–34.6% SL; body depth 33.3–35.2% SL; predorsal length 25.8–29.3% SL; pre-anus length 49.3–56.1% SL; pectoral-fin length 25.1–29.5% SL; pelvic-fin length 13.3–16.5% SL; caudal-peduncle depth 9.1–9.7% SL; caudal-peduncle length 15.8–17.9% SL; eye diameter 25.4–30.2% HL; interorbital width 31.1–36.1% HL; snout length 23.8–26.6% HL; upper-jaw length 32.0–34.4% HL.

 

計数形質：背鰭6–7棘，25–29軟条；臀鰭3棘，19–20軟条；胸鰭20–21軟条；腹鰭1棘，5軟条；鰓耙数6–7+16–17=22–24；側線鱗数 84–89；脊椎骨数10+15=25．計測形質：頭長 28.4–34.6% SL；体高33.3–35.2% SL；背鰭前長25.8–29.3% SL；肛門前長49.3–56.1% SL；胸鰭長25.1–29.5% SL；腹鰭長13.3–16.5% SL；尾柄高9.1–9.7% SL；尾柄長15.8–17.9% SL；眼径25.4–30.2% HL；両眼間隔31.1–36.1% HL；吻長23.8–26.6% HL；上顎長32.0–34.4% HL.

特　徴　体は長卵形で，側扁する．吻端は丸く，吻長は眼径よりもわずかに短い．口は比較的小さく，上顎後端は眼の前縁直下を越える．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．背鰭始部は鰓蓋（主鰓蓋骨）の直上に位置する．背鰭棘は短く，皮膚に固着し，鰭膜で連続しない．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．眼の上方に鱗はない．食道嚢をもつ．頭部と体は青味がかった茶色で，各鰭は淡褐色．

分　布　南太平洋，南インド洋，南大西洋，南アフリカ（Parin and Piotrovsky, 2004）．

備　考　ミナミクロメダイ属Schedophilus (Cocco, 1839)はインド洋に3種が報告されている（Parin and Piotrovsky, 2004）．本種は，背鰭の総鰭条数（棘条＋軟条）が32–36，臀鰭の総鰭条数が22–24，脊椎骨数が25 であることによって本海域の同属種と識別できる[S. huttoni (Waite, 1910)は 背鰭の総鰭条数50–60，臀鰭の総鰭条数34–41，脊椎骨数30–31；S. maculatus Günther, 1860は背鰭の総鰭条数35–38，臀鰭の総鰭条数25–27，脊椎骨数29]（Parin and Piotrovsky, 2004）．また，本種はナンキョクメダイHyperoglyphe antarctica (Carmichael, 1818)にも類似するが，本種のほうがより多くの背鰭条数と臀鰭条数をもつこと（D VI–VIII, 25–29; A III, 19–20 vs. D VIII, 19–22; A III, 14–16），および眼の上方に鱗が集まる小領域がないことで異なる（ナンキョクメダイにはある）．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 slightly shorter than eye diameter. Mouth moderately small, posterior end of maxilla extending beyond anterior margin of eye. A single row of minute conical teeth on both jaws. Vomer, palatine, and tongue lacking teeth. Dorsal-fin origin located above opercle. Dorsal-fin spines short and embedded in skin, not connected by fin membrane. Pectoral fin long, falcate, its posterior end reaching to above anus. Pelvic fin short, its base situated below pectoral-fin base. Caudal fin deeply forked. Scales small and cycloid, deciduous, extending to cover bases of dorsal and anal fins. Pharyngeal sac present. Head and body brown with bluish tinge, and all fins light brown.

Distribution  South Pacific, South Indian and South Atlantic oceans, South Africa (Parin and Piotrovsky, 2004).

Remarks  Three species of the genus Schedophilus (Cocco, 1839) have been recorded in the Indian Ocean (Parin and Piotrovsky, 2004). This species can be distinguished from its two congeners in the study area by having 32–36 total dorsal-fin elements (spines + soft rays), 22–24 total anal-fin elements, and 25 vertebrae [vs. 50–60 total dorsal-fin elements, 34–41 total anal-fin elements, and 30–31 vertebrae in S. huttoni (Waite, 1910); and 35–38 total dorsal-fin elements, 25–27 total anal-fin elements, and 29 vertebrae in S. maculatus Günther, 1860] (Parin and Piotrovsky, 2004). This species is also similar to Hyperoglyphe antarctica (Carmichael, 1818), but differs from the latter in having more dorsal- and anal-fin rays (D VI–VIII, 25–29 and A III, 19–20 vs. D VIII, 19–22 and A III, 14–16) and lacking a small patch of scales above the eye (vs. present in H. antarctica). Schedophilus velaini is targeted by trawl and longline fishing.

(M. Okamoto)