272 
Psyche 
[Vol. 93 
investigated have a common host species, Leptothorax (T.) reced- 
ens, which is not parasitized by any other Epimyrma species. The 
numbers of Epimyrma-Q 5 are variable, but low in all the 3 species, 
which therefore should represent “degenerate slavemakers” as was 
already stated for E. kraussei (Buschinger & Winter 1983). Field 
data and laboratory breeding results indicate that the 3 species have 
a highly 9-biased sexual production, intranidal mating and in- 
breeding, that the young 99 overwinter in their mother nests and 
invade own host colonies in spring. Crossbreeding experiments 
reveal that a strict genetical isolation is lacking. The 3 original sam- 
ples, comprising only few specimens, were apparently described as 
separate species mainly because they were found in quite distant 
localities, and because the variability of their slight morphological 
differences could not be evaluated then. 
We therefore synonymize E. vandeli Santschi 1927 and E. foreli 
Menozzi 1921 with E. kraussei Emery 1915. 
Population structure and reproductive biology in this species, 
however, are highly remarkable (Winter & Buschinger 1983). The 
inbreeding system with young queens spreading on foot, and thus 
over only short distances, must result in an extremely restricted gene 
flow, even if a rare mating of sexuals from neighboring colonies 
might occur. The populations from different continents (northern 
Africa, southern Europe) and islands (Sardegna, Corsica), but also 
from more neighboring localities (southern France, northern 
Spain), must have been isolated for a very long time. This isolation, 
in our opinion, is responsible for the differences in coloration, 
morphology of wings and genitalia, and worker numbers, which we 
observed in certain populations. The replacement of one of these 
characters by another one can only occur through interdemic 
selection, through supplantation of a local population by another 
one which is somewhat more effective. Since E. kraussei, however, 
does not inhabit large, continuous habitats, but instead forms 
numerous small, patchily distributed populations, this process must 
be slow and rare. The reduction of worker numbers in favor of a 
higher 9 production should be highly adaptive in this species. Since, 
however, the genetical basis for this evolution cannot spread, e.g., 
through flying we may speculate that different demes just have 
reached different degrees of worker reduction. Crossbreeding ex- 
periments have been started in order to find out whether or not 
