264 
Psyche 
[Vol. 93 
1950)], and with Myrmoxenus gordiagini Ruszky 1902, a species 
very closely related to Epimyrma (Buschinger et al. 1983, Fischer 
unpubl.). No host species of Epimyrma and no other Leptothora- 
cine species having this particular karyotype could yet be found. 
Thus, we may suppose that E. foreli as well has the karyotype of the 
genus, and no arguments for or against the synonymization of the 3 
snecies in auestion can be derived from our karyological studies. 
Biological data 
Host specificity 
The host species of E. kraussei in all populations investigated, 
including those ascribed to E. vandeli and E. foreli, is invariably 
Leptothorax ( Temnothorax ) recedens (Nylander 1856). All other 
Epimyrma species have different host species belonging to the sub- 
genus Myrafant (Kutter 1973, Espadaler 1982, Buschinger & Winter 
1985), and no other Epimyrma species has ever been found with 
Temnothorax hosts. In or close to the localities where we have 
collected E. kraussei (table 1) we usually found several other Lepto- 
thorax species, particularly often L. (Myrafant) unifasciatus (La- 
treille 1798), which then was parasitized by the slavemaking ants, E. 
ravouxi or Chalepoxenus sp., but never by E. kraussei. Host speci- 
ficity, is thus apparently a good character for species discrimination 
in the genus Epimyrma, and the joint use of Temnothorax by E.v., 
E.f, and E.k. is an argument for their synonymization. 
Population Data 
Reproductive biology and colony foundation 
Epimyrma species, as far as is known, may differ considerably 
with respect to their sex ratios. Thus, E. ravouxi has a sex ratio of 
about 1.5 ( 5 / 2 ); in E. kraussei from population no. 14 (Tignale) this 
ratio is about 0.3 in field colonies; and 0.2 in laboratory culture 
(Winter & Buschinger 1983), and in E. Corsica it is 0.08 (Buschinger 
& Winter 1985). Sex ratios correspond well with the reproductive 
biology of the species concerned: E. ravouxi is characterized by 
extranidal mating, whereas E. kraussei (pop. no. 14 Tignale) and E. 
Corsica mate inside the mother nests and thus continually inbreed. 
The inseminated, dealate 22 of E.k. and E.c. remain in the mother 
