サギフエ科　Macroramphosidae                          Snipefishes

20 ミナミサギフエ

Centriscops humerosus (Richardson, 1846)                 Banded Yellowfish, Banded Bellowfish

Specimens examined: 6 (SNFR 19285, 19286, 19290, 19291, 19303, 19304; 138–181 mm SL), 572–988 m depth.

Counts: D VII, 16–17; A 18–19; P₁ 16–17; P₂ I, 4; GR 20–21 (total); V 9+16=25. Measurements: head length 46.3–49.5% SL; body depth at pectoral-fin base 39.3–42.3% SL; body depth at anus 38.6–41.2% SL; first dorsal-fin-base length 16.7–20.7% SL; second dorsal-fin-base length 11.4–12.6% SL; anal-fin-base length 14.5–15.2% SL; second dorsal-fin-spine length 20.1–25.5% SL; predorsal length 90.3–96.9% SL; pre-anus length 72.6–77.8% SL; pectoral-fin length 18.6–22.3% SL; pelvic-fin length 5.0–8.7% SL; caudal-peduncle depth 7.0–7.6% SL; caudal-peduncle length 12.4–14.0% SL; eye diameter 20.6–25.3% HL; interorbital width 14.3–17.2% HL; snout length 56.3–62.2% HL.

計数形質：背鰭7棘，16–17軟条；臀鰭18–19軟条；胸鰭16–17軟条；腹鰭1棘，4軟条；鰓耙数20–21（総数）；脊椎骨数9+16=25．計測形質：頭長46.3–49.5% SL；胸鰭始部における体高39.3–42.3% SL；肛門における体高38.6–41.2% SL；第1背鰭基底長16.7–20.7% SL；第2背鰭基底長11.4–12.6% SL；臀鰭基底長14.5–15.2% SL；第2背鰭棘長20.1–25.5% SL；背鰭前長90.3–96.9% SL；肛門前長72.6–77.8% SL；胸鰭長18.6–22.3% SL；腹鰭長5.0–8.7% SL；尾柄高7.0–7.6% SL；尾柄長12.4–14.0% SL；眼径20.6–25.3% HL；両眼間隔14.3–17.2% HL；吻長56.3–62.2% HL.

特　徴　体は楕円形で，強く側扁する．吻部は管状で著しく長く，その先端部にある口に歯はない．背鰭始部と臀鰭始部はともに体の後半部に位置する．第2背鰭棘は後縁に鋸歯があり，長大で，その長さは体長の約1/4から1/5．胸鰭は細長く，斜め上方を向く．腹鰭は小さく，その長さは眼径よりも短い．尾鰭の後縁は円い．鱗は小さい櫛鱗で硬く，表皮に固着して，剥がれにくい．峡部から腹鰭にかけての腹中線上には骨質隆起が存在する．胸鰭上方の背側部に骨質板がある．項部は隆起し，短い絨毛状の突起が密集する．側線はない．雌では頭部は赤く，体には6本の赤色の斜帯がある（雄では頭部は紫がかった黒色で，体にはおよそ７本前後の暗色の波線模様がある）．

分　布　大西洋南東部（アルゼンチン，ウルグアイ，ブラジル），大西洋南西部（トリスタンダクーニャ），南インド洋（セントポール島，アムステルダム島），太平洋南西部（オーストラリア南部，ニュージーランド），太平洋南東部（チリ），南アフリカ（Duhamel, 1995; Pakhorukov, 2001）．

備　考　本種はカワリサギフエNotopogon xenosoma Regan, 1914に類似するが，本種は項部に短い絨毛状の突起が密集した領域をもつこと，および体側には明瞭な斜帯があることで異なる（カワリサギフエの後頭部には長い剛毛が密集しており，体側に斜帯はない）．本種の体色は性的二型があり，また成長にともなって変化する（Menni and Miquelarena, 1979）．

（岡本）

Description  Body oval and strongly compressed. Snout tube-like and extremely long, mouth at its tip toothless. Origins of dorsal and anal fins located on posterior part of body. Second dorsal-fin spine with serrations on posterior margin, long and thick, its length about 1/4–1/5 of SL. Pectoral fin slender, directed obliquely upward. Pelvic fin small, its length shorter than eye diameter. Posterior margin of caudal fin rounded. Scales small, ctenoid, stiff, and adhered to skin, not deciduous. Midline of ventral margin between isthmus and pelvic-fin base forming bony ridge. Bony plates present on dorsolateral surface of body above pectoral fin. Nape raised, with a dense patch of downy hair-like projections. Lateral line absent. Head red, body with 6 red oblique bands in female (head black tinged with purple, body with about seven dark wavy stripes in male).

Distribution  Southeastern Atlantic (Argentina, Uruguay and Brazil), Southwestern Atlantic (Tristan da Cunha), South Indian (St. Paul and Amsterdam Islands), Southwestern Pacific (southern Australia and New Zealand), and Southeastern Pacific (Chile) Oceans; South Africa (Duhamel, 1995; Pakhorukov, 2001).

Remarks  This species is similar to Notopogon xenosoma Regan, 1914 but differs by having a dense patch of downy hair-like projections on the nape and distinct oblique bands on the side of body (vs. having a patch of long bristles and lacking oblique bands in N. xenosoma). The body color of this species is sexually dimorphic, and also changes with growth (Menni and Miquelarena, 1979).

(M. Okamoto)