456
D.M. COHEN:
Table 4. Genus Acanthurus (Family Acanthuridae) in the Indian Ocean
Red Sea
W. Indian
E. Indian
W. Pacific
Cent. Pacific
sohal
X
polyzona
X
tennenti
X
melanosternon
X
pyroferus
X
X
X
glaucopareius
X
X
X
bleekeri
X
X
X
X
X
xanthopterus
X
X
X
X
X
nigrofuscus
X
X
X
X
X
gahhn
X
X
X
X
X
leucosternon
X
X
X
bariene
X
X
triostegus
X
X
X
X
lineatus
X
X
X
X
mata
X
X
X
X
guttatus
X
X
X
dussumieri
X
X
X
thompsoni
X
X
X
nigroris
X
X
X
western Indian Ocean; 2 species are found in the eastern Indian Ocean and Pacific but
not to the west; 13 species are widespread, living from the western Indian Ocean to the
Pacific.
Although 52 species seem ridiculously few on which to base conclusions, a consistent
pattern seems to emerge. It may be summarized as follows: Red Sea endemics, 13%;
western Indian Ocean (in some instances Red Sea as well but not including Red Sea
endemics) only, 22%; eastern Indian Ocean only, 6%; eastern Indian Ocean to the
western or central Pacific, 15%; widespread, occurring from the Red Sea or western
Indian Ocean to the western or central Pacific, 48%. Particularly notable is the fact that
all species common to the eastern and western Indian Ocean are also found in the Pacific.
The distribution in the Indian Ocean of the shorefish family Serranidae, the sea basses,
has been discussed by POSTEL, FOURMANOIR and GUEZE (1963), and although most of
their analyses are not comparable with the system followed in the present paper, it is
significant that these authors found 44% of 64 Indian Ocean serranids to be widespread
in occurrence, with distributions ranging from the western Indian Ocean through the
Indo-Australian Archipelago.
The genus is a more subjective taxonomic category and represents a greater degree
of information pooling but, here too, the same pattern emerges. The 23 genera of salariine
blennies are circumtropical with 16 living in the Indian Ocean (Table 5; data from
SMITH-VANIZ and SPRINGER, 1971). Only 1 genus is endemic to the Red Sea; 1 genus is
restricted to the western Indian Ocean; 2 genera are found in the western and eastern
Indian Oceans but not in the Pacific; none live only in the eastern Indian Ocean; 2 genera
occur in the eastern Indian Ocean and Pacific; 9 genera are widespread, living from the
western Indian Ocean to the Pacific, and represent 62% of the total. Here again, about
half the taxa are widespread and small degrees of endemism are found in the Red Sea
and the western Indian Ocean.
D.M. COHEN:
Table 4. Genus Acanthurus (Family Acanthuridae) in the Indian Ocean
Red Sea
W. Indian
E. Indian
W. Pacific
Cent. Pacific
sohal
X
polyzona
X
tennenti
X
melanosternon
X
pyroferus
X
X
X
glaucopareius
X
X
X
bleekeri
X
X
X
X
X
xanthopterus
X
X
X
X
X
nigrofuscus
X
X
X
X
X
gahhn
X
X
X
X
X
leucosternon
X
X
X
bariene
X
X
triostegus
X
X
X
X
lineatus
X
X
X
X
mata
X
X
X
X
guttatus
X
X
X
dussumieri
X
X
X
thompsoni
X
X
X
nigroris
X
X
X
western Indian Ocean; 2 species are found in the eastern Indian Ocean and Pacific but
not to the west; 13 species are widespread, living from the western Indian Ocean to the
Pacific.
Although 52 species seem ridiculously few on which to base conclusions, a consistent
pattern seems to emerge. It may be summarized as follows: Red Sea endemics, 13%;
western Indian Ocean (in some instances Red Sea as well but not including Red Sea
endemics) only, 22%; eastern Indian Ocean only, 6%; eastern Indian Ocean to the
western or central Pacific, 15%; widespread, occurring from the Red Sea or western
Indian Ocean to the western or central Pacific, 48%. Particularly notable is the fact that
all species common to the eastern and western Indian Ocean are also found in the Pacific.
The distribution in the Indian Ocean of the shorefish family Serranidae, the sea basses,
has been discussed by POSTEL, FOURMANOIR and GUEZE (1963), and although most of
their analyses are not comparable with the system followed in the present paper, it is
significant that these authors found 44% of 64 Indian Ocean serranids to be widespread
in occurrence, with distributions ranging from the western Indian Ocean through the
Indo-Australian Archipelago.
The genus is a more subjective taxonomic category and represents a greater degree
of information pooling but, here too, the same pattern emerges. The 23 genera of salariine
blennies are circumtropical with 16 living in the Indian Ocean (Table 5; data from
SMITH-VANIZ and SPRINGER, 1971). Only 1 genus is endemic to the Red Sea; 1 genus is
restricted to the western Indian Ocean; 2 genera are found in the western and eastern
Indian Oceans but not in the Pacific; none live only in the eastern Indian Ocean; 2 genera
occur in the eastern Indian Ocean and Pacific; 9 genera are widespread, living from the
western Indian Ocean to the Pacific, and represent 62% of the total. Here again, about
half the taxa are widespread and small degrees of endemism are found in the Red Sea
and the western Indian Ocean.