Sponges of Onotoa 
M. W. deLaubenfels 1 
Onotoa is an atoll consisting of two prin- 
cipal and three lesser islets, with a lagoon, 
and is situated far out in the Pacific Ocean 
at about 1° 50 ; south latitude and 175° 30' 
east longitude. It is in the southern part of 
the archipelago known as the Gilbert Islands, 
only Tamana and Arorai being farther south. 
In July and August, 1951, sponges were 
collected at Onotoa by Preston E. Cloud, Jr., 
and Albert H. Banner. These were deposited 
in the United States National Museum, and 
all were given the museum number 195237. 
They were sent to me for study in October, 
1952 and returned to Washington in Novem- 
ber, 1952. Many of the species were being 
described as new in my monograph of the 
Sponges of the Western Pacific, therefore pub- 
lication of this Onotoa collection was post- 
poned until the monograph appeared. 
Twenty identifiable species of sponge occur 
in the collection, 10 collected by Banner only, 
7 by Cloud only, and 3 by both. All those 
collected by Cloud had detailed ecological 
notes, but (with a few exceptions) those col- 
lected by Banner did not. 
The monograph referred to covers collec- 
tions from the Mariana, Palau, Caroline, and 
Marshall Islands. The latter are nearest to the 
Gilberts, and of all the Marshalls, Ebon is 
nearest to Onotoa. Of the present collection, 
approximately half the species occur also at 
1 Department of Zoology, Oregon State College, 
Corvallis, Oregon. Manuscript received July 6, 1954. 
Ebon. The word approximately is used be- 
cause of the existence of some probably mu- 
tual possessions that are based, however, 
upon uncertain identifications. Certainly there 
is significant resemblance between the sponge 
faunas of Ebon and Onotoa. It has been my 
observation that each oceanic island that one 
visits has very few of the same species that 
occur on its neighbors, but still fewer from 
those islands that are yet farther away. 
Mid-pacific islands in general tend to have 
a certain type of sponge population; this con- 
sists of a few species that are peculiar to the 
island, (perhaps having evolved there), a few 
species that are cosmopolitan, but these a 
quite different assortment than the cosmo- 
politan species that are present on the nearest 
neighbors, and a few species (such as Stylotella 
agminata ) that are widespread in the Pacific. 
This situation is conspicuously different from 
that occurring in the corals. 
Only one certainly new species occurs in 
the present collection, but it is also a new 
genus. Had the collecting been done by a 
sponge specialist, probably two or three 
others would have been found. It is to be 
expected that there would be about 40 species 
at such an island as Onotoa, whereas half 
that number are now available. Many sponges 
are so placed or characterized that they are 
likely to be overlooked. On the other hand, 
other marine objects often resemble sponges 
most deceptively. An interesting item some- 
what of this nature concerns the specimen 
137 
