Nonmarine Moliusks of Rongelap Atoll, Marshall Islands 
Norman J. Reigle 1 
It HAS long BEEN realized that the coral atolls 
and low islands of the Pacific possess a meager, 
limited, and characteristic snail fauna which are 
of little zoogeographical value (Pilsbry; 1900, 
1916, Cooke; 1926). Cooke (1934) has de- 
scribed the terrestrial molluscan fauna of one 
of the typical lower islands; and recently Solem 
( 1959) has listed the major molluscan elements 
of the atoll fauna. 
In recent years the Marshall Islands served as 
a center for United States atomic testing. This 
large operation brought about many changes in 
the life of certain islands, including mass stuff- 
ings of human populations. In view of the 
possible influence of population movements and 
of testing on the fauna of an area, it might be 
helpful to record the available distribution rec- 
ords, not only to learn what is happening to 
the moliusks in the course of the nuclear tests 
but also to obtain a better knowledge of the 
fauna in this area. 
Published records of nonmarine moliusks in 
the Marshall Islands are very scarce. Although 
this group is composed of 32 islands and 867 
reefs (Robson, 1946), the nonmarine moliusks 
of only 2 of the islands have been reported. The 
Marshalls are a homogenous series of islands, 
with the highest elevation about 33 ft (Osborn, 
1944). Consequently, these islands lack the 
more interesting and diverse land snails which 
are found on the higher islands, and it is not 
surprising that little has been written about 
this vast area. 
Pease ( I860) described six new species from 
Ebon which have since been reduced to two 
(see Cooke and Kondo, I960: 180-191; H. B. 
Baker, 1940: 190; Pilsbry, 1917:151-152). 
Schnee (1904) listed three land snails and one 
oncidiid slug from Jaluit. His paper was con- 
cerned primarily with vertebrates and only a 
few moliusks were collected. Since the paper 
1 Museum of Zoology, University of Michigan, Ann 
Arbor, Michigan. Manuscript received August 13 , 
1962. 
of Pease from which most of the published 
Marshall Island records have been derived con- 
tains only descriptions of new species, and the 
Schnee records are only incidental, it is apparent 
that these records are incomplete. Recently 
Omphalotropis fragilis Pease has been recorded 
on two of the atfolls (Marshall, 1950); and 
Abbott (1958) described a new subspecies from 
Eniwetok and also recorded it from two neigh- 
boring atolls, including Rongelap. Cooke and 
Kondo (I960), in their revision of the Tornatel- 
linidae and Achatinellidae, supplied additional 
records for the area. Several records from the 
"Marshall Islands” which really refer to Nauru, 
stem from a paper by O. Boettger (1904). 
Prior to 1914 this island was part of the German 
Marshall Islands Protectorate, but is not gen- 
erally considered geographically a - part of the 
Marshall Islands. 
Rongelap Atoll, also known under the names 
of Rimski-Korsakoff L, Rongelab, Rongorappu 
To, and Pescadore, is located in the northeastern 
portion of the Marshall Islands at 11° 20' N, 
166° 50' E (Fig. 1). A general description and 
more complete maps of Rongelap and neigh- 
boring atolls, of Bikini, Eniwetok, and Rongerik, 
were published by Taylor (1950). 
The land snail fauna of Rongelap is typical 
of a Pacific atoll. As one would suspect, all of 
the species have a wide range of distribution in 
the Pacific. The only exception is one subspecies, 
thus far recorded only from the Marshall Islands 
(Abbott, 1958). The various species recorded 
were unequally distributed on the islands. Of 
the 10 species mentioned here, 6 represent new 
records for the Marshall Islands. 
MATERIAL STUDIED 
This study was based upon a collection made 
in September 1959 by Dr. I. Eugene Wallen, 
aquatic biologist with the Atomic Energy Com- 
mission. Collections were made on five islands 
in the atoll, and most were made within 150 
ft from shore. Of the 450 specimens collected, 
126 
