Genus /sistius Gill, 1864
Dorsal fins subequal, both situated in rear third of precaudal length; no D spines. Snout length subequal to mouth
width. Teeth markedly dissimilar in the 2 jaws. Ventral surface of head and body sprinkled with minute photophores,
which emit a greenish glow at night. Two species. Isistius
plutodus Garrick & Springer, 1964 is known only from the
Gulf of Mexico and off Okinawa.
5.20 Isistius brasiliensis
(Quay & Gaimard, 1824)
Scymnus brasiliensis Quoy & Gaimard, 1824: 198 (Brazil). Isistius
brasiliensis: Bass et al., 1976: 44*.
15-18/1/15-18
Teeth 12-15/1/12-15'
Colour usually dark brown dorsally, distinctly paler
below except for blackish band across throat; tips of C lobes
blackish. About 14 cm at birth; males mature at 32-37 cm,
females at 40-44 cm; attains 50 cm. Feeds largely on squid,
but also bites circular plugs of tissue from large pelagic animals such as tuna, billfishes and cetaceans (Jones, 1971).
Most records from tropical waters of Atlantic and Pacific
Oceans; not yet reported from our area, but records from
QX] T
5: SQUALIDAE (DOGFISHES)
the Gulf of Guinea and Mauritius indicate that it will eventually turn up here.
Genus Oxynotus Rafinesque, 1810
Large dorsal fins with spines of which only the tips are visible. No anal fin. Three or 4 species, 1 in our area.
Flatiron shark
5.21 Oxynotus centrina
(Linnaeus, 1758)
Strykysterhaai
Squalus centrina Linnaeus, 1758: 233 (Mediterranean). Oxynotus centrina: Smith, SFSA No. 548*; Karrer, 1973: 196. Oxynotus sp.: Bass et al.,
1976: 8* .
First D spine slopes forwards. Large spiracle close to eye.
5-5
Teeth 4-1-4' Precaudal vertebrae 63.
Uniformly brown. Our specimens 55 and 56 cm, trawled
between Cape Town and Walvis Bay in 270 - 280 m; tentatively ascribed to Oxynotus centrina, but with a comparatively short interdorsal distance as compared to published
figures of North Atlantic specimens. In North Atlantic attains 80 cm; also known from Mediterranean.
5.20 /sistius brasiliensis: 43 cm female (Gulf of Mexico; after Garrick & Springer, 1964). T & d as in 2.1.
5.21 Oxynotus centrina: 55 cm female (Walvis Bay). T = teeth.
59
Dorsal fins subequal, both situated in rear third of precaudal length; no D spines. Snout length subequal to mouth
width. Teeth markedly dissimilar in the 2 jaws. Ventral surface of head and body sprinkled with minute photophores,
which emit a greenish glow at night. Two species. Isistius
plutodus Garrick & Springer, 1964 is known only from the
Gulf of Mexico and off Okinawa.
5.20 Isistius brasiliensis
(Quay & Gaimard, 1824)
Scymnus brasiliensis Quoy & Gaimard, 1824: 198 (Brazil). Isistius
brasiliensis: Bass et al., 1976: 44*.
15-18/1/15-18
Teeth 12-15/1/12-15'
Colour usually dark brown dorsally, distinctly paler
below except for blackish band across throat; tips of C lobes
blackish. About 14 cm at birth; males mature at 32-37 cm,
females at 40-44 cm; attains 50 cm. Feeds largely on squid,
but also bites circular plugs of tissue from large pelagic animals such as tuna, billfishes and cetaceans (Jones, 1971).
Most records from tropical waters of Atlantic and Pacific
Oceans; not yet reported from our area, but records from
QX] T
5: SQUALIDAE (DOGFISHES)
the Gulf of Guinea and Mauritius indicate that it will eventually turn up here.
Genus Oxynotus Rafinesque, 1810
Large dorsal fins with spines of which only the tips are visible. No anal fin. Three or 4 species, 1 in our area.
Flatiron shark
5.21 Oxynotus centrina
(Linnaeus, 1758)
Strykysterhaai
Squalus centrina Linnaeus, 1758: 233 (Mediterranean). Oxynotus centrina: Smith, SFSA No. 548*; Karrer, 1973: 196. Oxynotus sp.: Bass et al.,
1976: 8* .
First D spine slopes forwards. Large spiracle close to eye.
5-5
Teeth 4-1-4' Precaudal vertebrae 63.
Uniformly brown. Our specimens 55 and 56 cm, trawled
between Cape Town and Walvis Bay in 270 - 280 m; tentatively ascribed to Oxynotus centrina, but with a comparatively short interdorsal distance as compared to published
figures of North Atlantic specimens. In North Atlantic attains 80 cm; also known from Mediterranean.
5.20 /sistius brasiliensis: 43 cm female (Gulf of Mexico; after Garrick & Springer, 1964). T & d as in 2.1.
5.21 Oxynotus centrina: 55 cm female (Walvis Bay). T = teeth.
59