ギンメダイ科 Polymixiidae
Beardfishes
10 クロブチギンメ（新称）
Polymixia
busakhini Kotlyar, 1992 Busakhin’s Beardfish
Specimen
examined: 1 (SNFR 19210; 279 mm SL), 723–824 m
depth.
Counts:
D V, 35; A IV, 16; P1 16; P2 I, 5; GR 3+8 (not including
1 rudiment on lower limb); LLS 34; scales above lateral line 8; scales below
lateral line 12; V 12+17=29.
Measurements: head length 33.7% SL; body depth 43.3% SL; eye diameter 30.0%
HL; interorbital width 22.7% HL; snout length 22.5% HL; upper-jaw length 57.6%
HL; lower-jaw length 60.4% HL; caudal-peduncle length 17.1% SL; caudal-peduncle
depth 10.3% SL; pectoral-fin length 19.4% SL; pelvic-fin length 12.0% SL; 4th anal-fin
spine length 7.2% SL; barbel length 67.7% HL; dorsal-fin base length 43.6% SL;
anal-fin base length 17.3% SL; pre-anus length 60.7% SL; pre-dorsal-fin length
52.8% SL; pre-anal-fin length 71.2% SL.
計数形質：背鰭5棘，35軟条；臀鰭4棘，16軟条；胸鰭16軟条；腹鰭1棘，5軟条；鰓耙数3+8（下肢の痕跡的な1本は含まない）；側線鱗数 34；側線上方鱗数8；側線下方鱗数12；脊椎骨数12+17=29．計測形質：頭長33.7%
SL；体高43.3%
SL；眼径30.0%
HL；両眼間隔22.7%
HL；吻長22.5%
HL；上顎長57.6%
HL；下顎長60.4%
HL；尾柄長17.1%
SL；尾柄高10.3%
SL；胸鰭長19.4%
SL；腹鰭長12.0%
SL；第4臀鰭棘長7.2%
SL；髭長67.7%
HL；背鰭基底長43.6%
SL；臀鰭基底長17.3%
SL；肛門前長60.7%
SL；背鰭前長52.8%
SL；臀鰭前長71.2%
SL．
特 徴 体は卵形で側扁する．頭長は体長の約1/3で，体高よりも短い．吻は丸く，突出せず，吻端は上顎先端の直上にある．眼は円形で大きく，眼径は吻長よりも大きい．口は大きく，上顎の後端は眼の後端の垂直下に達する．両顎，鋤骨，および口蓋骨には絨毛状歯帯がある．喉部に1対の長いヒゲがある．背鰭始部は腹鰭基部よりも後方に位置し，背鰭基底は長い．臀鰭には4本の棘があり，4番目が最も長くて太い．胸鰭基部は腹鰭基部よりも前方にあり，胸鰭後端は腹鰭後端とほぼ同じ垂直下で，肛門に達しない．肛門は体の後半部に位置する．尾鰭の後縁は深く湾入する．鱗は中庸大の櫛鱗で，剥がれにくい．吻部から眼下域，喉部，鰓膜，鰭は無鱗．側線は1本で，明瞭．体の背部は黒褐色，腹部は銀白色．背鰭と臀鰭の前部の縁辺，および尾鰭両葉の後縁は黒褐色．
分 布 インド洋西部，タスマン海（Kotlyar,
1993）．
備 考 本種は背鰭軟条数が33–36であること（アラメギンメP. berndti
Gilbert, 1905は28–31），鰓耙総数（痕跡的なものは含めない：Kotlyar，1993）が11であること（P. fusca
Kotthaus, 1970は14–17）によって，調査海域に生息する同属他種から識別できる．清水（1990）が報告したニュージーランド産のギンメダイ属の1種Polymixia
sp.は，Kotlyar
(1993)によって本種とみなされた．本標本の体長（279
mm SL）は，本種の最大の記録となる．
（岡本）
Description Body
oval and laterally compressed. Head about 1/3 of SL, its length shorter than
body depth. Snout round, not protruding, tip of snout just above upper jaw. Eye
large and circular, its diameter greater than snout length. Mouth large,
posterior margin of upper jaw extending to a vertical through posterior margin
of orbit. Villiform tooth bands present on both jaws, vomer, and palatine. A
pair of long barbels present at gular portion. Dorsal-fin origin posterior to
pelvic-fin base, dorsal-fin base long. Anal fin with four spines, fourth spine
longest and thick. Pectoral-fin base anterior to pelvic-fin base; posterior end
of pectoral fin below that of pelvic fin, not reaching anus. Anus located on
posterior half of body. Caudal fin deeply forked. Scales moderately sized,
ctenoid, not deciduous. No scales on snout, suborbital region, gular portion,
branchiostegal membrane, and all fins. Lateral line single and conspicuous.
Dorsal half of body blackish brown, ventral half of body silvery white.
Anterior margins of dorsal and anal fins and posterior margins of both lobes of
caudal fin blackish brown.
Distribution Western
Indian Ocean,
Remarks This
species can be distinguished from its congeners in the study area by having
33–36 dorsal-fin soft rays (vs. 28–31 in P.
berndti Gilbert, 1905) and 11 total gill rakers (excluding rudiments, see
Kotlyar, 1993) (vs. 14–17 in P. fusca
Kotthaus, 1970). Polymixia sp. from
(M.
Okamoto)