ハタ科　Serranidae                    Groupers, Sea Basses

 

25 ミカンオキハナダイ（新称）

Lepidoperca coatsii (Regan, 1913)  Westwind Drift Orange Perch

 

Specimen examined: 1 (SNFR 19297; 127 mm SL), 643–702 m depth.

Counts: D X, 17; A III, 8; P₁ 17; P₂ I, 5; GR 9+24=33; LLS 42; V 10+16=26. Measurements: head length 39.4% SL; body depth 39.5% SL; dorsal-fin base length 57.9% SL; anal-fin base length 18.9% SL; eye diameter 33.4% HL; interorbital width 24.0% HL; snout length 24.4% HL; upper-jaw length 46.4% HL; lower-jaw length 49.0% HL; caudal-peduncle length 23.2% SL; caudal-peduncle depth 11.7% SL; pectoral-fin length 32.0% SL; pelvic-fin length 22.8% SL.

 

計数形質：背鰭10棘，17軟条；臀鰭3棘，8軟条；胸鰭17軟条；腹鰭1棘，5軟条；鰓耙数9+24=33；側線鱗数42；脊椎骨数10+16=26．計測形質：頭長39.4% SL；体高39.5% SL；背鰭基底長57.9% SL；臀鰭基底長18.9% SL；眼径33.4% HL；両眼間隔24.0% HL；吻長24.4% HL；上顎長46.4% HL；下顎長49.0% HL；尾柄長23.2% SL；尾柄高11.7% SL；胸鰭長32.0% SL；腹鰭長22.8% SL．

特　徴　体は側扁し，体高は高い．頭部は大きく，主鰓蓋骨に扁平な棘が3本ある．前鰓蓋骨の後縁は鋸歯状．下鰓蓋骨と間鰓蓋骨の接合部付近および間鰓蓋骨の下縁は鋸歯状．口は大きく斜位で，上顎後端は眼の中心の直下を越える．両顎には幅の狭い絨毛状歯帯があり，前方を向く犬歯が上顎先端部に1対，下顎先端部に2対．下顎の中央付近には後方を向く犬歯が1対ある．鋤骨，口蓋骨には絨毛状歯帯がある．内翼状骨と舌（基舌骨）に歯はない．眼は大きく，頭長の約1/3．吻は短く，吻長は眼径よりも短い．両眼間隔域は平坦で，眼径より狭い．胸鰭は長く，その後端は臀鰭始部の直上を越える．腹鰭は短く，肛門に達しない．尾鰭の後縁はわずかに湾入する．鱗は基部に微小棘帯をもつ櫛鱗で，体の鱗は大きく，頭部と各鰭の基部を被う鱗は小さい．体色は背部で橙色，腹部では淡桃色．各鰭は黄色で，背鰭棘条部の鰭膜には褐色斑がある．

分　布　南大西洋中央部と東部，インド洋南西部（Roberts, 1989; Anderson and Heemstra, 2012）．

備　考　オキハナダイ属はハナダイ亜科に分類されており，鱗は櫛鱗で，鱗の基部から中央付近にかけて微小棘帯があること，主上顎骨に鱗があること，前鰓蓋骨の腹縁に前向棘がないこと，背鰭が10棘15–21軟条，側線鱗数38–51，鰓耙数（総数）29–41という形質の組み合わせによって他の属から識別される（Roberts, 1989; Anderson and Heemstra, 2012）．本属は10有効種が知られるが，そのうちの9種はニュージーランドからオーストラリアに分布し，本種のみが南大西洋中央部と東部およびインド洋南西部から知られている．本種は背鰭棘条部に褐色斑をもつこと，側線鱗数が42–51，側線下方鱗数が13であることから同属他種から識別できる（Roberts, 1989）．

（岡本）

 

Description  Body deep, compressed. Head large, with three flat opercular spines. Posterior margin of preopercle serrated. Subopercle and interopercle near their junction and lower margin of interopercle serrated. Mouth large, oblique, posterior end of upper jaw extending to a vertical through center of eye. Both jaws with narrow bands of villiform teeth, one and two pairs of anteriorly directed canine teeth at near symphyses of upper and lower jaws respectively; one pair of recurved canine teeth at near mid-point of lower jaw. Villiform teeth bands on vomer and palatine. Endopterygoid and tongue (basihyal) without teeth. Eye large, its diameter ca. 1/3 of head length. Snout short, its length shorter than eye diameter. Interorbital space flat, its width narrower than eye diameter. Pectoral fin long, posterior tip extending beyond level of anal-fin origin. Pelvic fin short, not reaching anus. Caudal fin slightly forked. Scales ctenoid with ctenial bases present proximal to marginal cteni; body scales large, small scales covered on head and fin bases. Dorsal body orange, pinkish white ventrally. All fins yellow, dark blotches present on interspinous membrane of dorsal fin.

Distribution  Central and eastern South Atlantic and western South Indian oceans (Roberts, 1989; Anderson and Heemstra, 2012).

Remarks  The genus Lepidoperca Regan, 1914 is distinguishable from other genera of Anthiinae by having ctenoid scales with ctenial bases present proximal to marginal cteni, scaly maxilla, no antrorse spines on the ventral margin of preopercle, dorsal-fin rays X, 15–21, lateral-line scales 38–51, and total gill rakers on the first arch 29–41 (Roberts, 1989; Anderson and Heemstra, 2012). The genus Lepidoperca comprises 10 valid species, nine of which are distributed in New Zealand and Australia, but L. coatsii is known from the central and western South Atlantic and the southwestern Indian oceans. This species can be distinguished from its congeners by having dark blotches on the interspinous membrane of the dorsal fin, 42–51 lateral-line scales, and 13 scales below the lateral line (Roberts, 1989).

(M. Okamoto)