Review of Labroides — RANDALL 
Labroides dimidiatus 
(Cuvier and Valenciennes) 
Fig. 1 
Labrus latovittatus Riippell, {non Lacepede), 
1835, Neue Wirbelth., Fische . . . , p. 2. 
Cossyphus dimidiatus Cuvier and Valenciennes, 
1839, Hist. Nat. des Poiss., vol. 13, p. 136. 
Labroides paradiseus Bleeker, 1851, Natuurk. 
Tijdschr. v. Nederland. Indie, vol. 2, p. 249. 
Labroides bicincta Saville-Kent, 1893, The 
Great Barrier Reef of Australia, p. 308, pi. 
16, fig. 4. 
Labroides caeruleo-lineatus Fowler, 1945, Acad. 
Nat. Sci. Phila., Proc., vol. 97, p. 65, fig. 7. 
type locality: Mauritius. 
This blue and black species is the most 
common and widespread of the genus, rang- 
ing from Africa to the tropical Pacific (where 
it is recorded from most major island groups). 
Labroides paradiseus Bleeker differs from 
dimidiatus in having a hooklike ventroanterior 
extension of the broad black band in the 
caudal fin. I have observed various degrees of 
intermediacy between typical dimidiatus and 
the paradiseus form, and I regard the latter as 
a color variety, as did Gunther (1881: 243). 
In the Society Islands and Tuamotu Archi- 
pelago I have seen no specimens of the para- 
diseus variety, although collections are not ex- 
tensive. In large collections from the Marshall 
Islands and the Philippines in the United 
States National Museum the paradiseus form 
predominates. 
At Makatea and Takaroa in the Tuamotu 
Archipelago, and to a lesser extent at Tahiti 
329 
and Moorea, another color variant was ob- 
served. Occasional adults have a dull red- 
orange region in the middle of the body be- 
low and adjacent to the median black band. 
In the Marquesas L. dimidiatus were seen with 
a red -orange area which was longer and oc- 
curred above as well as below the black band. 
Barnard (1927: 749) described two color 
varieties of the species at Natal, East Africa, 
one with a dark stripe across the base of the 
pectoral fin and one without. He stated that 
the color of the species in Africa is blue or 
yellow with a black longitudinal band. Smith 
(1949: 291), also reporting on the species 
from East Africa, described the color as vary- 
ing rapidly from light pink through straw 
yellow to dark blue, apparently at will and 
according to the emotional state of the fish. I 
have never seen L. dimidiatus in the Pacific 
pink or yellow instead of blue, nor have I 
observed any rapid color changes. With age 
there is a loss of brilliance and a lightening of 
the blue color. Below the median black band 
large adults are nearly white. 
A juvenile specimen, 24 mm. in standard 
length, collected by the author in Tahiti, was 
colored in life as follows: black with a band 
of deep blue about a pupil diameter in width 
beginning at upper lip and passing backward 
through upper part of eye (lower edge of 
band at upper edge of pupil) on to nape, 
where it is nearly two pupil diameters in 
width, and thence on to back, where it gradu- 
ally narrows until it terminates dorsally on 
caudal peduncle; the black middorsal region, 
which is bordered by a blue band on each 
side, is broadest on the head and narrows as 
Fig. 1 . Labroides dimidiatus, 83 mm., Society Islands. Caudal fin not expanded, hence emarginate appearance. 
