A Revision of the Surgeon Fish Genera Zebrasoma and Paracanthurus 1 
John E. Randall 
The surgeon fishes (Acanthuridae), like 
many of the families of tropical marine fishes, 
are in need of thorough taxonomic study on 
a world- wide basis. In the present paper, 
which is one of a series on the classification 
of the family (see Randall, 1955), the species 
of two of the genera, Zebrasoma and Paracan- 
thurus , are considered. The question of 
whether Zebrasoma flavescens (Bennett) is or 
is not a dichromatic species is discussed in 
detail. Specimens of the three rare species of 
Zebrasoma , Z. gemmatum (Cuvier and Valen- 
ciennes), Z. xanthurum (Blyth), and Z. ros- 
tratum (Gunther) were examined, and the 
validity of these species is confirmed. The 
postlarval Zebrasoma and early juvenile Para- 
canthurus are figured for the first time. 
An attempt is made to give complete syn- 
onymies. Mere listings or records of species 
with insufficient data to permit identification 
are generally not included among the syn- 
onyms. When first citations are given without 
a locality, this information was not supplied 
by the author(s). A locality is listed with later 
citations of a species only when it appears 
that the author examined specimens from this 
locality. In the synonymies misidentifications 
are indicated by a period after the scientific 
name. 
1 A portion of a thesis submitted to the Department 
of Zoology, University of Hawaii, in partial fulfillment 
of the requirements for the degree of Doctor of 
Philosophy. Contribution no. 70 of the Hawaii Marine 
Laboratory in cooperation with the Department of 
Zoology and Entomology, University of Hawaii. Man- 
uscript received March 11, 1955. 
In making dorsal and anal fin ray counts, 
the last two rays are counted as one only when 
they share the same basal element. All rudi- 
ments are included in the gill raker counts. 
In addition to the usual counts of gill rakers 
(herein designated anterior gill rakers), counts 
of the more ridge-like rakers along the inner 
surface of the first gill arch (posterior gill 
rakers) are given. 
Most of the work on this paper was done 
at the United States National Museum, and 
the author is indebted to Leonard P. Schultz, 
Ernest A. Lachner, and Robert H. Kanazawa 
for their kind assistance. All of the Zebrasoma 
and Paracanthurus in the collections of the 
Academy of Natural Sciences of Philadelphia, 
Museum of Comparative Zoology at Harvard 
College, California Academy of Sciences, 
Stanford Natural History Museum, Bernice 
P. Bishop Museum, and University of Hawaii 
were examined. 
Zebrasoma Swainson 
Zebrasoma Swainson (1839: 256). (Type spe- 
cies by monotypy, Acanthurus velifer Bloch.) 
Body compressed, ovate, depth contained 
1.4 to 2.1 times in standard length (this and 
other proportional measurements based on 
specimens over 50 mm. in standard length); 
head length 2.9 to 3.7 in standard length; 
snout produced; caudal peduncle with a single 
folding spine on each side, fitting into a 
shallow depression; length of caudal spine 3 
to 6 in head length; least depth of caudal 
396 
