THE TETRAGONODERUS GROUP OF CHLAENIUS 
(COLEOPTERA: CARABIDAE) IN THE 
INDO-AUSTRALIAN ARCHIPELAGO 
By P. J. Darlington, Jr. 
Museum of Comparative Zoology 
The two new Chlaenius here described belong to a zoogeographi- 
cally interesting group of the genus characterized by exceptionally 
short, subtransverse mandibles. The group may be called the 
Chlaenius tetragonoderus group. C. tetragonoderus Chaudoir itself 
occurs from the southeastern corner of Asia (Burma) to Celebes 
and the Philippines, with subspecies in the Moluccas (Louwerens 
1956) and the Palau Islands (Darlington 1970) ; it is recorded also 
from Timor (Louwerens 1953). The group is represented in New 
Guinea and northeastern Australia by maculiger Castelnau (Darling- 
ton 1968, 2-5), on the Mariana Is. in Micronesia by a very distinct 
endemic species ( marianensis Darlington 1970), and on Timor and 
the Solomons by new species described below. It will be seen that 
the group has differentiated mainly in the Indo-Australian archi- 
pelago and western Pacific Islands. It is in fact the only group 
of the genus that has differentiated over so wide an area of the 
islands. Its success on islands may be due partly to its habitat. 
Many Chlaenius live in wet places, but tetragonoderus and macu- 
liger (which I have collected in the Philippines and New Guinea 
respectively) and presumably the other species of the group appa- 
rently live away from water, on the ground in rain forest, and need 
not depend on finding permanent fresh water when they reach a new 
island. 
Key to Chlaenius of tetragonoderus group 
1. Elytra duller with intervals closely punctate with punctures of 
moderate size, the punctures not or not much sparser toward 
base of inner intervals; elytra often spotted 2 
— • Elytra more shining ; elytral punctation either much sparsier 
toward base of inner intervals or coarser (with pronotum more 
coarsely punctate too) ; elytra not spotted 4 
2. Head and pronotum submetallic (greenish or bluish) ; legs usually 
pale; length c. 10-12 mm (3 subspecies) tetragonoderus 
— Head and pronotum not metallic; legs dark 3 
3. Prothorax narrow (width/length 1.21 and 1.22); pronotum 
closely punctate throughout; length c. 12 mm timorensis 
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