On the World-wide Dispersal of a Hawaiian Barnacle, 
Balanus am phitrite hawaiiensis Broch 1 
Huzio Utinomi 2 
In recent years a great deal of attention has 
been given by many workers, especially by 
marine ecologists and oyster planters, to the in- 
troduction of an Australian barnacle, Elminius 
modes tus Darwin, into British waters and to its 
subsequent rapid spread along the continental 
European coasts from Brittany to the mouth of 
the Elbe River. The most recent extensive re- 
views of the occurrence of this barnacle on those 
coasts have been given by Den Hartog (1953) 
and Kiihl (1954). Similarly, another instance 
of the introduction of an adventive barnacle into 
British coastal waters has also focused more at- 
tention on the possibility of other importations 
of many harmful foreign animals, as well as the 
extension of their natural geographical distribu- 
tion. These studies strongly suggest that trans- 
portation on ships’ bottoms or as stowaways 
among oysters is the chief means of migration 
(Allen, 1953; Coe, 1956). 
The second example of a barnacle imported 
into European waters has long been considered 
to be Balanus amphitrite var. denticulata Broch, 
which was originally described by Broch ( 1927 ) 
from the Suez Canal. Since the first record of its 
occurrence on the southern coasts of Britain by 
Bishop (1950), most of the European workers, 
especially field ecologists who are not acquainted 
with the Pacific species of barnacles, have over- 
looked the fact that it is identical with Balanus 
amphitrite forma hawaiiensis Broch (1922), 
which is thought to be native to the Hawaiian 
Islands. 
The object of this paper is to state the reasons 
for considering both of these forms as identical, 
at least with each other and possibly with other 
1 Contributions from the Seto Marine Biological 
Laboratory, No. 335. Manuscript received January 2, 
1958. 
2 Seto Marine Biological Laboratory, Sirahama, 
Wakayama-ken, Japan. 
forms ( or subspecies ) ; and to present the al- 
leged distribution of these related forms, as far 
as can be determined from the records of their 
occurrence. 
ACKNOWLEDGMENTS 
I am especially indebted to Mr. William A. 
Newman, Pacific Islands Central School, Truk, 
East Caroline Islands, for data of occurrence in 
America, and to Mr. Kasio Ota, Zoological In- 
stitute, Agriculture Faculty, Hokkaido Univer- 
sity, for information on habitats. Thanks are 
also due to Dr. Masaru Kato, Zoological Insti- 
tute, Kyoto University, for translating a Russian 
paper. 
identity OF subspecies denticulata WITH 
SUBSPECIES hawaiiensis 
Balanus amphitrite Darwin (1854) com- 
prises many local forms, occasionally treated as 
either "subspecies” or "varieties,” which are 
diversified in the number of teeth on the labrum. 
Most of the subspecies have only three teeth on 
each side of a median notch. The other sub- 
species almost always have four teeth, or a larger 
number (Hiro, 1938). Even in the subspecies 
having three or four teeth, the actual number is 
apt to vary among specimens, but in such cases 
the innermost one is either small or only rudi- 
mentary. 
The two subspecies, hawaiiensis and denticu- 
lata, have such a multidenticulate labrum. The 
same is true of Balanus ehurneus Gould and of 
B. improvisus Darwin, which are found as mi- 
grants on ships sailing between America and 
Europe. The number of teeth is also variable, 
ranging between 8 and 20; in most cases 10 to 
13 larger teeth are found on each side, but never 
fewer than 8. 
The most outstanding features in external ap- 
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