1988] 
Heinze & Buschinger — Leptothorax 
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(Gervet, 1964). In most cases the coexistence of several inseminated 
females in one nest is transient, and it resembles the regulation of 
queen number in obligatorily monogynous ants after colony foun- 
dation by pleometrosis (Buschinger, 1974a). In leptothoracine ants, 
on the other hand, functional monogyny is total and may be a 
lasting phenomenon. Only the queen has fully developed ovaries; 
those of the supernumerary females are always undeveloped. The 
presence of b->A-females with elongated ovarioles in colonies of 
Leptothorax spec. A is restricted to a short period of time and leads 
to colony fission or, as was observed in the lab, to aggressive be- 
havior toward the young female and finally to her death. Whether 
dominance hierarchies exist in colonies with several supernumerary 
females, as in Polistes, is not yet known. 
Our observations suggest that, comparable to primary and secon- 
dary polygyny, functional monogyny in Leptothoracini may arise in 
two ways. Intermorphic females, and perhaps gynomorphic females 
also, are easily accepted in their mothers’ colonies after mating, and 
they may stay there for several breeding cycles. The other possibil- 
ity, a pleometrosis-like colony foundation with several inseminated 
young females, one of which becomes fertile, has been observed in 
the field only two or three times. The find of a gynomorphic super- 
numerary female in a colony with an intermorphic queen which 
produced only intermorphic female sexuals does not necessarily 
indicate that foreign females are adopted; the gynomorph might 
have accompanied a sister during pleometrosis or budding. 
According to our results, all species belonging to Leptothorax s. 
str., including L. acervorum, L. muscorum, and L. gredleri from 
Eurasia, may have colonies with several inseminated females, as is 
the fact too in some of the parasitic species, e.g. L. kutteri (Buschin- 
ger, 1968a), and in the genus Formicoxenus, which seems closely 
related to Leptothorax s. str. In the subgenus Myrafant and its 
satellite genera Epimyrma, Myrmoxenus, Chalepoxenus, and Pro- 
tomognathus, however, most species are obligatorily monogynous. 
In Myrafant and its parasites, facultative polygyny occurs only 
occasionally as in the North American species L. longispinosus, L. 
ambiguus, and L. curvispinosus (Alio way et al., 1982), or in Epi- 
myrma algeriana (Buschinger et al., in prep.). In studies on poly- 
gyny in different populations of L. longispinosus , a latitudinal cline 
in the frequency of multiple-queened nests has been suggested; 
