NOTES 
Faunal Spedation in New Georgia, Solomon Islands 
Some 16 years ago the writer made certain 
contributions to the knowledge of the fauna 
of San Cristobal, the most eastern of the main 
Solomon Islands (Lever, Limn. Soc. London, 
Proc. 148(2): 82-83, 1936); this was followed 
by more general notes on the whole group 
(Lever, Trop. Agr. [Trinidad] 20(2): 40-42, 
1943 ) . The purpose of the present paper is to 
draw attention to an extensive local develop- 
ment of species formation in the New Geor- 
gia group of islands lying in the centre of the 
whole Solomon archipelago. 
Besides the main island of New Georgia, 
which is some 50 miles in length, the group 
comprises seven closely associated islands in- 
cluding Kolombangara which, though only 
15 miles in diameter, rises to a height of over 
5,500 feet. All these islands, despite their near- 
ness to one another, are separated by very 
much deeper water than any other comparable 
group in Melanesia (Fig. 1). Thus, although 
Kolombangara is only 10 miles from Gizo, 
the intervening sea is 245 fathoms deep, and 
soundings between Rendova and Wana Wana, 
which are only 12 miles apart, reached 552 
fathoms. 
Recognition of an inter-insular variation in 
the animals of these islands was first noted 
in the birds by Mayr {Amer. Mus. Novitates 
522: 1-22, 1932), who showed that while the 
thick-head Pachycephala pectoralis is represent- 
ed by a different species in each of the larger 
Solomon Islands, in New Georgia alone are 
several species found. Later he showed that 
specimens of the white eye, Zosterops rendovae, 
from Vella Lavella and Bagga were distinct 
from those occurring in Ganongga and Gizo 
to the south and Kolombangara to the south- 
east {Amer. Nat. 74: 249-278, 1940). In fact 
the flying time of 3.4 minutes which these 
Fig. 1. Map of the New Georgia Group, Solomon 
Islands. The outlines of this map have been taken large- 
ly from United States Army maps, as the most recent 
official British map (No. 17/30 of Directorate of Colo- 
nial Surveys) shows Arundel Island as a portion of New 
Georgia although in fact a deep-water channel occurs 
between the former and the intervening Woodford 
Island, with a constriction at the Diamond Narrows. 
The D.C.G. map marks, but leaves unnamed, the large 
island of Vella Lavella; the spot levels have, however, 
been followed here. The most recent edition (1945) 
of the British Admiralty chart No. 2392 indicates only 
tentative outlines for the coast of western Vella Lavella 
and adds that Gananggo may be 2 to 4 miles further 
west than its marked position. (Altitude in feet, sea 
depth in fathoms.) 
small birds take to fly 1.7 kilometers would 
have enabled them to bridge the gap which 
however, is sufficient to allow of subspecies 
occurring on the different islands. 
That this same phenomenon occurs in in- 
sects has not heretofore been appreciated. 
However, well-marked subspecies of the wee- 
vil Exophthaimida coerulescens Gunther, taken 
by the writer in 1936, were shown to exist by 
Marshall {Roy. Ent. Soc. London, Proc., Ser. B. 
10(4): 51-55, 1941). The typical form, from 
Vella Lavella, is opalescent grey with many 
black spots whereas E. c. ganongae is metallic 
green, and E. c. kolombangarae is fawn with 
small dark spots. A further point of interest 
250 
