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Psyche 
[Vol. 88 
In one of the latter instances, observations were made inter- 
mittently over a period of 2 days, during which time a force of about 
15 workers was regularly maintained on the plant. These workers 
gave outward-facing aggressive displays (mandibles barred) when 
the plant was disturbed. A small contingency of workers was also 
clustered among leaf litter at the base of the plant, apparently 
controlling access to the plant and aphids. Detense of “tending 
rights” may be important since other aggressive, aphid-tending ants 
such as Pheidole were present in the same locality. The colony of the 
purpurea workers was located in a rotten log 5m distant. Workers 
returning to the colony from the ginger plant showed high fidelity to 
a particular route which involved following the ground for half the 
distance and then proceeding along a decumbent liana (one of 
many) which led back to the log. 
Thus, despite the “lone forager” status of most impressa group 
workers, short-term recruitment, co-operative food retrieval, and 
(in at least one species) persistent, long-range trails, may be used. 
Excepting persistent trails, species in the impressa group appear to 
show a level of individual foraging and recruitment similar to that 
described for the myrmicine ant, Novomessor (Holldobler, et al., 
1978). 
The species in the impressa group with the most sophisticated 
foraging and recruitment behavior {purpurea ) is the only member 
whose colonies are entirely monogynous and queenright. It is 
tempting to speculate that widespread polygyny and worker repro- 
duction in other Rhytidoponera species may have constrained 
ergonomic improvements because of a reduction in the efficacy of 
colony-level selection (cf. Oster & Wilson, 1978). 
Summary 
The five known species of the Rhytidoponera impressa group 
collectively inhabit a variety of mesic forest habitats (from wet 
sclerophyll to tropical rainforest) along the east coast of Australia, 
with one species {purpurea ) also occurring in montane rainforest of 
New Guinea. R. chalybaea has invaded mesic anthropogenic 
habitats (parks and gardens) in the Sydney region. All species show 
partial sympatry with at least one other species. 
Most colonies are located in rotten logs or under stones. There 
are significant differences between species in the frequencies with 
