205: CHAETODONTIDAE (BUTTERFL YFISHES)
205.24 Heniochus monoceros
Cuvier, 1831
PLATE 78
Masked coachman
Gemaskerde koetsier
Heniochus monoceros Cuvier, in Cuv. & Val., 1831: 100, PI. 176
(Mauritius); Burgess, 1978: 247*; Smith, 1980: 179.
D XI-XII,24-26; A III,17-19; P 16-18; LL51-64. Adults with prominent
hump on nape and a short "horn" in front of each eye.
Attains 24 cm. Indo-West Pacific, south to Cape Vidal.
205.24 Heniochus monoceros: 14 em (N. Mozambique).
Family No. 206: OPLEGNATHIDAE
by P.C. Heemstra
Knifejaws
Kraaibekke
Body oblong, somewhat compressed, covered with
minute ctenoid scales. Dorsal fin single, with 11 or 12
spines; anal fin spines 3. Teeth fused to form a strong
parrot-like beak similar to that of the parrotfishes, Family
Scaridae (but the two families are not at all closely related);
prejuveni\es with separate incisiform teeth; no teeth on
vomer or palatines.
Young coloured very differently from adults. Common in
rocky areas from shore out to 100 m; feed on benthic invertebrates. Good eating. Apparently an anti-tropical group
occurring at Japan, Australia and on the west coast of South
America. One valid genus.
Genus Oplegnathus Richardson, 1840
Hoplegnathus Richardson, 1849 is an unjustified emendation. Ostorhinchus Lacepede, 1802 was considered a
senior synonym by Whitley (1959); but we agree with Fraser
(1972) that Ostorhinchus is a nomen dubium. Seven species;
our 3 species are endemic to the South African region.
632
KEY TO SPECIES
1a D XII,1l-14; A III,ll-13 ................................ ....... O. conwayi
1b D XI,20-24; A III,14-17 ............................... ... .................... 2
2a Body depth 2.5-2.7 in SL; scales begin on
top of head behind eye ....................................... O. peaolopesi
2b Depth 1.8-2.1 in SL; scales begin over front of
eye ................................................................. O. robinsoni
206.1 Oplegnathus conwayi
Richardson, 1840
PLATE 78
Cape knifejaw
Kaapse kraaibek
Oplegnathus conwayi Richardson, 1840: 27 (? Australia; Richardson's
presumed type-locality is in error, as the species is known only from South
Africa); Richardson, 1849: 144, PI. 7, Fig. 1; Smith, SFSA No. 461*; Smith
& Smith, 1966: 68*. Ichthyorhamphus pappei Castelnau, 1861: 35 (Kalk
Bay). Hoplegnathus algoensis Gilchrist & Thompson, 1916: 56* (Algoa
Bay). Hoplegnathus conwayi: Barnard, 1927: 505*.
D XII,1l-14; A III,ll-13; P 18-20; lower GR 15-17. Body depth 1.8-2.8
in SL, more elongate with age. Top of head naked.
Attains 90 cm. Common from False Bay to Natal. Seldom
takes a hook, but easily speared.
206.1 Op/egnathus conwayi: 50 em (Algoa Bay).
206.2 Oplegnathus peaolopesi
Smith,1946
Mozambique knifejaw
Mosambiekse kraaibek
Oplegnathus peaolopesi Smith, 1946: 798 (Delagoa Bay, Mozambique);
Smith, SFSA No. 463*.
D XI,20-21; A III,16; P 18-19; lower GR 15.
206.2 Op/egnathus pea%pesi: 60 em holotype (S. Mozambique).
205.24 Heniochus monoceros
Cuvier, 1831
PLATE 78
Masked coachman
Gemaskerde koetsier
Heniochus monoceros Cuvier, in Cuv. & Val., 1831: 100, PI. 176
(Mauritius); Burgess, 1978: 247*; Smith, 1980: 179.
D XI-XII,24-26; A III,17-19; P 16-18; LL51-64. Adults with prominent
hump on nape and a short "horn" in front of each eye.
Attains 24 cm. Indo-West Pacific, south to Cape Vidal.
205.24 Heniochus monoceros: 14 em (N. Mozambique).
Family No. 206: OPLEGNATHIDAE
by P.C. Heemstra
Knifejaws
Kraaibekke
Body oblong, somewhat compressed, covered with
minute ctenoid scales. Dorsal fin single, with 11 or 12
spines; anal fin spines 3. Teeth fused to form a strong
parrot-like beak similar to that of the parrotfishes, Family
Scaridae (but the two families are not at all closely related);
prejuveni\es with separate incisiform teeth; no teeth on
vomer or palatines.
Young coloured very differently from adults. Common in
rocky areas from shore out to 100 m; feed on benthic invertebrates. Good eating. Apparently an anti-tropical group
occurring at Japan, Australia and on the west coast of South
America. One valid genus.
Genus Oplegnathus Richardson, 1840
Hoplegnathus Richardson, 1849 is an unjustified emendation. Ostorhinchus Lacepede, 1802 was considered a
senior synonym by Whitley (1959); but we agree with Fraser
(1972) that Ostorhinchus is a nomen dubium. Seven species;
our 3 species are endemic to the South African region.
632
KEY TO SPECIES
1a D XII,1l-14; A III,ll-13 ................................ ....... O. conwayi
1b D XI,20-24; A III,14-17 ............................... ... .................... 2
2a Body depth 2.5-2.7 in SL; scales begin on
top of head behind eye ....................................... O. peaolopesi
2b Depth 1.8-2.1 in SL; scales begin over front of
eye ................................................................. O. robinsoni
206.1 Oplegnathus conwayi
Richardson, 1840
PLATE 78
Cape knifejaw
Kaapse kraaibek
Oplegnathus conwayi Richardson, 1840: 27 (? Australia; Richardson's
presumed type-locality is in error, as the species is known only from South
Africa); Richardson, 1849: 144, PI. 7, Fig. 1; Smith, SFSA No. 461*; Smith
& Smith, 1966: 68*. Ichthyorhamphus pappei Castelnau, 1861: 35 (Kalk
Bay). Hoplegnathus algoensis Gilchrist & Thompson, 1916: 56* (Algoa
Bay). Hoplegnathus conwayi: Barnard, 1927: 505*.
D XII,1l-14; A III,ll-13; P 18-20; lower GR 15-17. Body depth 1.8-2.8
in SL, more elongate with age. Top of head naked.
Attains 90 cm. Common from False Bay to Natal. Seldom
takes a hook, but easily speared.
206.1 Op/egnathus conwayi: 50 em (Algoa Bay).
206.2 Oplegnathus peaolopesi
Smith,1946
Mozambique knifejaw
Mosambiekse kraaibek
Oplegnathus peaolopesi Smith, 1946: 798 (Delagoa Bay, Mozambique);
Smith, SFSA No. 463*.
D XI,20-21; A III,16; P 18-19; lower GR 15.
206.2 Op/egnathus pea%pesi: 60 em holotype (S. Mozambique).