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Psyche 
[Vol. 92 
integrated polydomous colonies. Thus, there could be differing 
degrees of tolerance between the workers of neighboring nests, and 
various levels of worker exchange between nests. 
Our study on intra-population genetic variation in R. sp 12 is a 
continuing one, the results for which will be reported elsewhere 
(Crozier et al., 1984, and in prep). In this paper we report observa- 
tions on colony maintenance and inter-nest interactions, made with 
the intention of furthering our understanding of the extent of the 
reproductive division of labor within colonies, and the degree of 
nest autonomy in natural populations. 
Rhytidoponera sp. 12 ANIC has also been referred to as R. mayri 
(Crozier et al., 1984) and as R. sp. B (Davidson and Morton, 1981). 
The acronym “ANIC” refers to provisional species recognised, but 
not yet named, by Dr. R. W. Taylor and held by the Australian 
National Insect Collection, maintained by the CSIRO Division of 
Entomology in Canberra (see Imai et al., 1977). 
Methods and Results 
Study site. 
The population studied is in Conservation Paddock of the Uni- 
versity New South Wales Arid Zone Research Station, north of 
Broken Hill, New South Wales, and is further described by Crozier 
etal. (1984). 
The dominant ant with respect to competitive interactions in the 
study site is Iridomyrmex viridiaeneus, a colony of which is asso- 
ciated with a grove of Acacia victoriae in the center. 
The observations reported here were made during September 
17-28 and November 9-15, 1983, although preliminary observations 
have been made over a number of years in connection with the 
relatedness studies. 
Reproductive state 
The ant nests are in hard clay soil and data from a number of 
excavations indicate that the lowest gallery reaches a depth of about 
1 m below ground level. We excavated two nests completely; one of 
these was a mature nest (excavated on November 15), in that it went 
down to the usual depth, whereas the other was an incipient colony 
(we observed it being established and it only achieved a depth of ca. 
16 cm) excavated on September 21. 
