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[Vol. 95 
colonies. Tab. II reveals the records from field and laboratory col- 
onies. The sex ratio (male/ female) is close to 0.43 both in the field 
and laboratory colonies, thus markedly female-biased. This is not 
substantially changed when the three laboratory-founded colonies, 
which only produced males (Tab. I, no. 4, 5, 8), are included; the sex 
ratio then would be 0.49, still more than 2 females per male. 
Discussion 
Our field and laboratory data clearly reveal that Chalepoxenus 
brunneus is a workerless parasitic ant, in contrast to the other spe- 
cies of this genus. Except for C. spinosus, of which only alate 
sexuals are known (Buschinger 1987), all other species have a 
worker caste, and C. muellerianus (including C. insubricus and C. 
siciliensis) afc well as C. kutteri have been shown to conduct slave 
raids. For C. tramieri (Cagniant 1983) dulotic life habits are also 
assumed. C. brunneus thus represents a “degenerate slavemaker” 
like several species in the genus Epimyrma, which are parasites of 
Leptothorax species (s.g. Myrafant and Temnothorax) as is Chale- 
poxenus (Buschinger and Winter 1985, Buschinger et al. 1987, 
Buschinger in press). 
As in the workerless Epimyrma Corsica and E. adlerzi, the C. 
brunneus females apparently are able to eliminate the host colony 
queens during parasitic colony founding, using the genus-specific 
technique of stinging them, while Epimyrma females throttle the 
host queens to death. Different from the dulotic Chalepoxenus 
species, however, where the host queen soon dies when stung, the L. 
marocanus queens are only paralyzed by the C.b. female, and may 
even recover, as was shown in one experiment, or die only after 
several days. Another difference refers to the behavior towards the 
host colony workers: In C. muellerianus and C. kutteri the parasitic 
queen stings most of the workers to death (some workers and the 
queen often escape), and takes over only their broods. C. brunneus , 
on the other hand, stings only part of the host workers, which also 
do not die immediately (only after several days), and she is accepted 
by the remainder of the adult host colony workers. This parallels 
our observations in Epimyrma, again, in that during colony founda- 
tion the Epimyrma queens also sting a small number of host 
workers (Buschinger and Winter 1985, Buschinger et al. 1987, 
Douwes et al. 1988), and are accepted by the others. Adoption of the 
