1985] 
Pamilo, Crozier, & Fraser — Rhytidoponera 
229 
The average relatedness level of 0.158 (± 0.037, 95% confidence 
limits) for this R. sp. 12 population (Crozier et al., 1984) would 
suggest that the average number of egglayers per nest yielding 
workers would be 5.8 (with 95% confidence limits 4. 6-7. 9), accord- 
ing to the formulas of Pamilo and Varvio-Aho (1979) and under the 
assumptions that these egg-layers are as closely related as workers 
on average, that they mate once and to unrelated males, and that 
they contribute equally to the next generation. The figure of 22 we 
observed requires confirmation by further excavations but, if con- 
firmed as typical, would indicate that one or more of these assump- 
tions are violated. If 22 mated workers did contribute to the next 
generation under these assumptions, then the mean relatedness level 
would be below 0.05. 
Data are also available for Rhytidoponera species with life- 
patterns differing to that of sp. 12 with regard to the observed 
proportions of mated workers. Haskins and Whelden (1965) found 
5.4% of the workers to be inseminated in R. metallica and 2.3% in 
R. inornata, both species that habitually lack differentiated queens 
in their colonies, but in which winged queens do occasionally occur. 
Ward (e.g., 1981, 1983) found that species in the impressa group 
have colonies of two kinds: those with a single differentiated queen 
each, and those lacking such queens but in which the reproductive 
role is taken over by some mated workers, as in sp. 12. Figures 
reported by Ward (1983) for 33 colonies of the latter type in confusa 
and chalybaea yield an estimate of 3.7% of the workers being insem- 
inated. While the various Rhytidoponera species may differ in the 
percentages of workers per colony that are inseminated, little can be 
inferred from the figures so far, because it is likely that the percen- 
tage varies with age and size of colonies, and with the time of the 
year collections are made, and these data are imperfectly recorded in 
the literature. 
The occurrence of oocytes in the ovarioles of most ants, mated or 
not, is striking. Whelden (1957) mentions that many workers in 
violacea have oocytes, and that the occurrence of oocytes is not 
linked to that of sperm in the spermatheca, but he gives no figures. 
Ward (1983) found much smaller percentages of unmated workers 
to have oocytes in impressa- group colonies. We suggest that the 
eggs of uninseminated workers are probably trophic eggs, eggs laid 
only to be eaten. Nutrient transfer by this means is common in the 
