243: ACANTHURIDAE (SURGEONFISHES, UNICORNFISHES)
243.11 Acanthurus triostegus
(Linnaeus, 1758)
PLATE 127
Convict surgeon
Bandiet-doktervis
Chaetodon triostegus Linnaeus, 1758: 274 (Indies). Acanthurus triostegus: Smith, SFSA No. 608*; Randall, 1956: 172*: van der Elst, 1981: 98*.
o IX,22-24; A 1II,19-22; P 14-16. Body depth 1.8-1.9 in SL; 12 upper
and 14 lower jaw teeth at 54 mm SL, and 16 upper and 18 lower teeth at
158 mm SL. Caudal spine small; C truncate to slightly emarginate.
Olivaceous grey, shading to white ventrally, with 6 narrow black bars on
head and body.
Attains 27 cm, but rarely exceeds 20 cm. A common
inshore species throughout the Indo-Pacific (except Red
Sea and Persian Gulf); also in eastern Pacific; south to the
Bashee River with post larvae drifting as far as Algoa Bay;
young abundant in tide-pools. Adults sometimes occur in
large aggregations feeding on benthic algae; in such schools
they overwhelm the territorial herbivorous fishes such as
the damselfishes (Pomacentridae). Randall (1961) has
studied the biology of the Hawaiian subspecies.
243.12 Acanthurus xanthopterus
Valenciennes, 1835
PLATE 129
Yellowfin surgeon
Geelvin-doktervis
Acanthurus xanthopterus Valenciennes, in Cuv. & Val., 1835: 215
(Seychelles); Randall, 1956: 215* Acanthllrus jllliginoslls (non Lesson):
Smith, SFSA No. 611*.
o IX,25-27; A 1II,23-25; P 16 or 17; GR 16-22. Body depth 1.8-2.25 in
SL; eye diameter 4.1-5.6 in head. Caudal spine 4.5-5.5 in head; 15 upper
and 16 lower jaw teeth at 97 mm SL, and 18 upper and 21 lower teeth at
320 mm SL; C concavity 4.6 in SL at 320 mm and 7 at 127 mm SL. Uniform
purplish grey (can be altered quickly to a pattern of light blue-grey with
highly irregular dark grey lines); a dull yellow area in front of eye. and a
lesser extension of yellow posterior to lower part of eye; 0 and A yellowish grey basally, shading outwardly to dull yellow, with 4 longitudinal.
broad, blue bands and a narrow bluish grey band at base; C purplish grey,
the base often dull white; P brown basally, yellow on outer third (except
extreme distal part which is hyaline).
Probably the largest of the surgeonfishes; recorded to
62.5 cm. Durban to eastern Pacific. Prefers protected
243.12 Acanthurus xanthopterus: 30 cm (Inhaca Id.).
816
deeper waters of bays and lagoons; may range over sand
flats far from the shelter of reefs or rock outcrops.
Genus Ctenochaetus Gill, 1885
D spines 8, the 1st small and easily overlooked. Six
species, 3 in our area.
KEY TO SPECIES
la No prominent black spot at rear end of 0 and A bases
(Y0l.ing striatus may have a small black spot basal at
rear of D only) ................................................................. 2
Ib Prominent black spot at rear end of D and A bases ..... C. binotatus
2a C lunate; C concavity 3.7-6.0 in SL; Drays 27-31;
A rays 24-28; body brown with longitudinal blue
lines .................................................................... C. striatus
2b C emarginate, the C concavity 13-20 in SL; Drays
25-27; A rays 22-25; body brown with blue dots ........... C. strigosus
243.13 Ctenochaetus binotatus
Randall,1955
PLATE 130
Twospot bristletooth
Tweekol-borseltand
Ctenochaetus binotatus Randall, 1955: 164 (Luzon, Philippines).
D VlII,24-27; A 1II,22-25; P 15-16. Body depth 1.9-2.15 in SL; upper
teeth with 6 denticulations (including tip) on lateral edge of distal
expanded ends; lower teeth with 3 lateral denticulations (including tip);
adults with as many as 42 upper and 45 lower jaw teeth; C lunate, concavity 4.5-6.4 in SL. Body orangish brown with longitudinal blue lines; blue
dots on head and thorax; a prominent black spot (nearly as large as pupil)
at iear end of D and A bases; D and A with faint longitudinal banding in
outer part; P rays light brownish except upper 2 rays which are dark
brown, the membranes clear; iris mainly blue.
Attains 22 cm. Indo-Pacific, south to Natal.
243.14 Ctenochaetus striatus
(Quoy & Gaimard, 1825)
Striped bristletooth
Gestreepte borseltand
Acanthurus striatus Quoy & Gaimard, 1825: 373, PI. 63, Fig. 3 (Guam).
Ctenochaetus strigosus (non Bennett): Smith, SFSA No. 614*. Ctenochaetus
striatus: Randall, 1955: 155.
243.14 Ctenochaetus striatus: 24 cm (Seychelles).
243.11 Acanthurus triostegus
(Linnaeus, 1758)
PLATE 127
Convict surgeon
Bandiet-doktervis
Chaetodon triostegus Linnaeus, 1758: 274 (Indies). Acanthurus triostegus: Smith, SFSA No. 608*; Randall, 1956: 172*: van der Elst, 1981: 98*.
o IX,22-24; A 1II,19-22; P 14-16. Body depth 1.8-1.9 in SL; 12 upper
and 14 lower jaw teeth at 54 mm SL, and 16 upper and 18 lower teeth at
158 mm SL. Caudal spine small; C truncate to slightly emarginate.
Olivaceous grey, shading to white ventrally, with 6 narrow black bars on
head and body.
Attains 27 cm, but rarely exceeds 20 cm. A common
inshore species throughout the Indo-Pacific (except Red
Sea and Persian Gulf); also in eastern Pacific; south to the
Bashee River with post larvae drifting as far as Algoa Bay;
young abundant in tide-pools. Adults sometimes occur in
large aggregations feeding on benthic algae; in such schools
they overwhelm the territorial herbivorous fishes such as
the damselfishes (Pomacentridae). Randall (1961) has
studied the biology of the Hawaiian subspecies.
243.12 Acanthurus xanthopterus
Valenciennes, 1835
PLATE 129
Yellowfin surgeon
Geelvin-doktervis
Acanthurus xanthopterus Valenciennes, in Cuv. & Val., 1835: 215
(Seychelles); Randall, 1956: 215* Acanthllrus jllliginoslls (non Lesson):
Smith, SFSA No. 611*.
o IX,25-27; A 1II,23-25; P 16 or 17; GR 16-22. Body depth 1.8-2.25 in
SL; eye diameter 4.1-5.6 in head. Caudal spine 4.5-5.5 in head; 15 upper
and 16 lower jaw teeth at 97 mm SL, and 18 upper and 21 lower teeth at
320 mm SL; C concavity 4.6 in SL at 320 mm and 7 at 127 mm SL. Uniform
purplish grey (can be altered quickly to a pattern of light blue-grey with
highly irregular dark grey lines); a dull yellow area in front of eye. and a
lesser extension of yellow posterior to lower part of eye; 0 and A yellowish grey basally, shading outwardly to dull yellow, with 4 longitudinal.
broad, blue bands and a narrow bluish grey band at base; C purplish grey,
the base often dull white; P brown basally, yellow on outer third (except
extreme distal part which is hyaline).
Probably the largest of the surgeonfishes; recorded to
62.5 cm. Durban to eastern Pacific. Prefers protected
243.12 Acanthurus xanthopterus: 30 cm (Inhaca Id.).
816
deeper waters of bays and lagoons; may range over sand
flats far from the shelter of reefs or rock outcrops.
Genus Ctenochaetus Gill, 1885
D spines 8, the 1st small and easily overlooked. Six
species, 3 in our area.
KEY TO SPECIES
la No prominent black spot at rear end of 0 and A bases
(Y0l.ing striatus may have a small black spot basal at
rear of D only) ................................................................. 2
Ib Prominent black spot at rear end of D and A bases ..... C. binotatus
2a C lunate; C concavity 3.7-6.0 in SL; Drays 27-31;
A rays 24-28; body brown with longitudinal blue
lines .................................................................... C. striatus
2b C emarginate, the C concavity 13-20 in SL; Drays
25-27; A rays 22-25; body brown with blue dots ........... C. strigosus
243.13 Ctenochaetus binotatus
Randall,1955
PLATE 130
Twospot bristletooth
Tweekol-borseltand
Ctenochaetus binotatus Randall, 1955: 164 (Luzon, Philippines).
D VlII,24-27; A 1II,22-25; P 15-16. Body depth 1.9-2.15 in SL; upper
teeth with 6 denticulations (including tip) on lateral edge of distal
expanded ends; lower teeth with 3 lateral denticulations (including tip);
adults with as many as 42 upper and 45 lower jaw teeth; C lunate, concavity 4.5-6.4 in SL. Body orangish brown with longitudinal blue lines; blue
dots on head and thorax; a prominent black spot (nearly as large as pupil)
at iear end of D and A bases; D and A with faint longitudinal banding in
outer part; P rays light brownish except upper 2 rays which are dark
brown, the membranes clear; iris mainly blue.
Attains 22 cm. Indo-Pacific, south to Natal.
243.14 Ctenochaetus striatus
(Quoy & Gaimard, 1825)
Striped bristletooth
Gestreepte borseltand
Acanthurus striatus Quoy & Gaimard, 1825: 373, PI. 63, Fig. 3 (Guam).
Ctenochaetus strigosus (non Bennett): Smith, SFSA No. 614*. Ctenochaetus
striatus: Randall, 1955: 155.
243.14 Ctenochaetus striatus: 24 cm (Seychelles).