Zebrasoma and Paracanthurus — Randall 
403 
Fig. 6. Zebrasoma rostratum (Gunther), (after Gun- 
ther, 1873). 
Zebrasoma rostratum (Gunther) 
Fig. Id; Fig. 6 
Acanthurus rostratus Gunther (1873: 117, pi. 
66, fig. B) (Society Islands). 
Zebrasoma rostratum Fowler (1928: 275); FFarry 
(1953: 152) (Raroia, Tuamotu Archipel- 
ago). 
Zebrasoma ( Laephichthys ) rostratum Fowler and 
Bean (1929: 262). 
Laephichthys rostratus Fowler (1938: 127) 
(Apataki, Tuamotu Archipelago); Fowler 
(1952: 25, fig.). 
Dorsal rays V (rarely IV), 23 to 25; anal 
rays III, 19 or 20; pectoral rays 15; anterior 
gill rakers 10 and posterior gill rakers 9 or 10 
(from 2 specimens, Society Islands); 84 and 
121 mm. specimens had 16 upper and lower 
teeth; a 166 mm. specimen had 16 upper and 
18 lower teeth, and a 170 mm. specimen 18 
upper and lower teeth. 
Longest soft dorsal ray 3 to 3.7 in standard 
length; fifth dorsal spine 3.7 to 4 in standard 
length; body depth about 2 in standard length; 
patch of setae in front of the caudal spine 
may or may not be present (two of seven 
specimens which could be sexed had well- 
developed setae and were males; the others 
lacked this bristle area and were females ; thus 
it is possible that this is a sexual character in 
this species). 
The long snout was believed to be the most 
characteristic feature; however, examination 
of a series of 10 specimens in the Stanford 
Natural History Museum, collected by R. R. 
Harry from Raroia Atoll in the Tuamotus, 
revealed considerable variability in snout 
length. The ratio of snout length (measured 
from tip of upper teeth to nearest edge of eye) 
to standard length (tip of snout to base of 
caudal fin) ranged from about 3 to 5. This 
variability is not associated with growth nor 
does it appear to be related to sex. 
I did not observe the dorsal spines to be 
noticeably stouter than those of other species 
of Zebrasoma , although Garrett’s drawing (in 
Gunther, 1873, reproduced herein as Fig. 6) 
shows them to be. 
Color (in alcohol) entirely black except 
membranes of pectoral fin which are clear, 
the caudal spine which is hyaline with a white 
sheath, and in some specimens a faint pale 
longitudinal band in the posterior half of the 
dorsal and anal fins. Harry (1953: 152) gives 
the life color as solid black with white caudal 
spine. 
Gunther described Acanthurus rostratus from 
Garrett’s notes and his painting of a 7.5 inch 
specimen. It has been presumed that the spec- 
imen is not in existence; however, I found 
two collected by Garrett, both 7.5 inches in 
total length, at the Museum of Comparative 
Zoology. It seems likely that one of these 
was the basis for the figure and therefore 
should be considered as the type. 
Fowler (1938: 128) thought that the velvety 
patch in front of the caudal spine was re- 
moved by the publishers of "Fische der Siid- 
see” from the painting. In this he is probably 
in error, for both of the Garrett specimens 
are females and lack this setous area. 
Zebrasoma rostratum is known only from the 
Society Islands and two islands in the Tua- 
motus. Harry collected his specimens from 
lagoon shore reefs at Raroia and observed the 
species also on lagoon coral heads. 
