1979] 
Brown — New Species of Proceratium 
345 
Observations of P. silaceum in artificial nests indicate that in this 
species the reflexed gastric tip is used to tuck the slippery eggs 
forward toward the mandibles when the eggs are being carried by the 
ants. Eggs of prey are stored in the ant nest in large numbers, recalling 
seed storage by the true harvester ants in subfamily Myrmicinae. 
Since Proceratium conceivably may belong to a group not too distant 
from the parent stock leading to the Myrmicinae, one may wonder 
whether the egg-collecting habit could have served as a key preadap¬ 
tation to seed harvesting. 
Ants of the related ectatommine genus Discothyrea also feed on 
arthropod eggs, probably usually those of spiders (though one small, 
undetermined Australian species has been found in nests of other 
ants). D. bidens (or near) is one egg-feeder in the wet mountain 
forests of New South Wales (Brown, 1958; embryos found in eggs 
packed in 4 nests of this ant appear to be those of spiders). In 1960,1 
found tiny spherical ova resembling spider eggs in a small nest cavity 
of a Discothyrea species (group of testacea ) on Barro Colorado 
Island in the Panama Canal Zone. In 1969, in wet mountain forest in 
Hogsback Reserve, eastern Cape Province, South Africa, I found 
numerous spherical eggs resembling those of spiders, and also a few 
more elongate ova, in a nest of Discothyrea poweri in rotten wood. 
Oligomyrmex species (subfamily Myrmicinae) may often be spe¬ 
cialist egg predators, particularly of eggs of termites in rotten wood. 
A populous colony of O. urichi that I found in rotten wood in forest 
along the Rio Don Diego, Guajira Dept., Colombia, contained many 
spherical eggs of an unknown arthropod, ranging in color from 
nearly white to reddish-brown in color, as though in different stages 
of cuticular tanning. These eggs were fed upon by soldiers and 
workers of the ant, and slowly disappeared during several months of 
captivity in a plaster-bottomed nest in the laboratory. 
W. H. Gotwald has given me specimens of a small new West 
African species of Plectroctena recently described as P. lygaria by 
Bolton, Gotwald and Leroux (1976), that was found to have stored 
large number of millipede eggs in its nest. The adult of at least some of 
the larger Plectroctena species are predators of adult millipedes. 
The above sampling, by no means exhaustive, should demonstrate 
that arthropod egg predation is a significant adaptive zone exploited 
by a variety of ants. 
