1981] 
Ward — Rhytidoponera impressa. II 
Table 1. Composition of small, isolated clusters of workers and brood (incipient 
worker-reproductive colonies?) in Rhytidoponera confusa, chalybaea, tasmaniensis, 
and fulgens. 
Species 
Locality 
Date 
No. 
workers 
Brood 
confusa 
Royal Natl. Park, 
5.xi. 1974 
5 
eggs, larvae 
N.S.W. 
" 
Pearl Beach, N.S.W. 
9.iv. 1977 
25* 
9 eggs, 8 larvae 
" 
Seal Rocks, N.S.W. 
14. vi. 1977 
13 
several larvae 
chalybaea 
Whian Whian State 
14. v. 1977 
9 
several larvae 
Forest, N.S.W. 
tasmaniensis 
nr. Wonboyn Lake, 
25.x. 1975 
6 
none seen 
N.S.W. 
fulgens 
Mt. Koghis, 
18. ii. 1977 
4* 
several larvae. 
New Caledonia 
one worker cocoon 
♦workers dissected, one inseminated. 
In view of the apparent scarcity of very small isolated clusters of 
workers and brood (of the size documented in Table 1, i.e. 5-25 
workers), it seems likely that colony fission in the impressa group 
often produces daughter colonies larger in size. (Mature worker- 
reproductive colonies, i.e. those with alates, contain, on average, 
about 150 workers.) More field observations on budding are 
needed; the small amount of information accumulated thus far 
suggests that nocturnal observations might be rewarding. It is also 
possible that some worker-reproductive colonies develop from 
former queen-right colonies in which the queen has died. 
The origin and development of queen-founded colonies in the 
impressa group has been more extensively documented. Incipient 
queen-right colonies have been observed repeatedly in the field 
(Table 3). Mated queens apparently disperse for some distance, 
undergo dealation, and search for a suitable nest site (under stones, 
rotting logs, etc.). Having located shelter, the queen excavates a 
small cavity, lays several eggs, and rears a small brood of workers, 
the first of these appearing within about 6 months (3-4 months in 
lab colonies). Unlike the claustral colony foundation typical of 
higher ants, queens forage outside the nest for food, and feed their 
larvae partly on insect prey. 
The available field information on incipient, queenright colonies 
suggests that they are usually founded in the spring and early 
