10 
Psyche 
[Vol. 87 
6) Discussion 
The present study has described various aspects of the biology of 
Leptothorax provancheri. With respect to polymorphsim in the 
female sex we can confirm the observations of Holliday (1903) with a 
difference only in the proportion of workers (ergatomorphs) without 
receptacle. While Holliday found only one such specimen in her large 
material from Colebrook, Conn., we had 24 workers without a 
receptacle as compared to 42 ergatomorphs with a receptacle. 
Furthermore, we found 2 intermorphs, both workerlike, but with 
ocelli present, without a spermatheca. It is a striking peculiarity ofL. 
provancheri that all morphologically different females, from dealate 
gynomorphs to seemingly normal workers (colony no. 9) may have 
receptacula and may even function as queens. Sometimes (e.g. colony 
9) intermorphs may live in a colony alongside an ergatomorphic 
queen (presumably their mother!). However, the same observation 
was made in Formicoxenus nitidulus (Buschinger and Winter 1976), 
where even sterile gynomorphs may exist in nests with intermorphic 
queens. 
A second striking fact is the presence of one or several inseminated 
females (not only newly fertilized ones) living together with the one 
fertile queen. Such a system, functional monogyny, has first been 
documented, among ants, in Leptothoraxgredleri Mayr (Buschinger 
1968), an independent ant. However, this social organization seems 
to be a characteristic of guest ants, since it was also found in 
Formicoxenus nitidulus and F. hirticornis. 
At present, we cannot yet decide, whether functional monogyny 
represents a plesiomorphic character which the guest ants and L. 
gredleri share because of their descent from a common ancestor with 
this organization, or whether this system provides any selective 
advantage for life as a guest ant. 
As already briefly discussed in section 4 and 5, the sexual behavior 
of L. provancheri and the karyotype as well do not provide significant 
arguments in favour of or against the hypothesis of a common 
phylogenetical origin of the guest ants. The sexual behavior, with 
females “calling” for males by use of a poison gland secretion as 
sexual pheromone, is common among Leptothoracini, especially 
among the social parasitic species. 
Thus, our data are not yet sufficient to prove that L. provancheri 
should belong to the genus Formicoxenus, or that there is a closer 
