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Psyche 
[Vol. 93 
worker number in E. kraussei populations is genetically determined. 
If so, we may predict that somewhere in the range of E. kraussei, 
populations will be found with high $ -numbers, and still actively 
slave-raiding, and other perhaps truly workerless demes. The 
evolution from outbreeding and slave-raiding towards intranidal 
mating and reduction of worker numbers and slave-making 
behavior, is an apparently widespread trait in the genus Epimyrma. 
Intranidal mating has been found also in E. bernardi and in E. 
Corsica, two species which are morphologically clearly separated 
from E. kraussei. Whereas E. bernardi “still” produces a consider- 
able amount of $$, E. Corsica has lost this caste completely 
(Buschinger & Winter 1985). Future studies will be necessary to find 
out whether worker reduction in Epimyrma is developing in several 
species or species groups independently, in parallel evolution, or 
whether the species with different worker numbers form a series of 
descent. The present study of E. kraussei evidently favors the first 
alternative. 
Summary 
Epimyrma vandeli Santschi 1927 and E. foreli Menozzi 1921 are 
junior synonyms of E. kraussei Emery 1915. A comparison was 
made of the type specimens and of newly collected material from the 
type localities of E.v. and E.f, and from numerous populations of 
E.k.. No reliable morphological differences could be found, despite 
a certain variation in $ genitalia, wing venation and body colora- 
tion of different populations. Karyotypes are homologous in all 
Epimyrma species and populations yet studied. The host species is 
Leptothorax ( Temnothorax ) recedens (Nylander 1856) in all E.k. 
populations including E.v. and E.f., whereas all other Epimyrma 
species have different host species. Epimyrma $ -numbers vary 
between populations, E.v. having a particularly low, and E.f. quite a 
high one, both, however, remaining within the range of the other 
E.k. populations. Sexual production is similar in all populations 
with a remarkably low (^-production. In all populations studied, 
sexuals mate within the mother nests, and inseminated, dealate 
young 99 remain there over winter until they leave for colony foun- 
dation in spring. E.v. and E.f. could be successfully crossbred with 
E.k., and sexuals from several E.k. populations among each other. 
Differences between E.k. populations presumably are due to their 
