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[Vol. 90 
related Epimyrma inquiline species, themselves degenerate slave- 
makers (Buschinger 1981, Buschinger and Winter 1982). Myrmica, 
on the other hand, has larger colonies and many species that are 
highly polygynous (Brian 1972; Elmes 1974a,b); this genus has given 
rise to at least 7 workerless inquiline species: Myrmica faniensis (van 
Boven 1970), Myrmica hirsuta (Elmes 1974a, 1978), Myrmica 
lampra (Francoeur 1968, 1981), Myrmica myrmecophila (Bernard 
1968), Myrmica quebecensis (Francoeur 1981), Sifolinia karavajevi 
(Kutter 1969) and Sifolinia laurae (Brian 1972), the Sifolinia species 
likely being congeneric with the other Myrmica species (Elmes 
1978). Monomorium is similar with polygynous species (Dennis 
1938, Cole 1940, Gregg 1945) and a number of congeneric inquilines 
(reviewed in Wilson 1971, see also Talbot 1979 and DuBois 1981). 
These inquiline species may have evolved through a process of some 
polygynous host queens acquiring the trait of laying only repro- 
ductive eggs (Buschinger 1970, Elmes 1978). To this list must be 
added the genus Pogonomyrmex whose basic biology is unlike any 
of the above three host genera. Colonies are substantially larger 
than Leptothorax, Myrmica or Monomorium (Lavigne 1969, Ro- 
gers et al. 1972, Whitford et al. 1976, MacKay 1981), strictly 
monogynous (Lavigne 1969, Holldobler and Wilson 1977, MacKay 
1981), with no slave-making or similar behavior in any species. 
Evolutionary processes giving rise to P. colei and P. anergismus are 
likely different from those that have given rise to the Leptothorax, 
Myrmica or Monomorium inquilines. Certainly, the idea of mul- 
tiple evolutionary pathways leading to workerless inquilinism is not 
new (see Wheeler 1919, Buschinger 1970, Wilson 1971). Continued 
study and search for workerless inquilines can only serve to clarify 
this challenging evolutionary process. 
Acknowledgements 
J. Alcock, G. B. Pollock, R. R. Snelling, G. C. Wheeler, and J. 
Wheeler have constructively reviewed earlier drafts of this manu- 
script. Laboratory space in Boulder City, Nevada was kindly 
provided by the University of Nevada Desert Research Institute, 
Desert Biology Research Center and the U.S. Bureau of Mines, 
Boulder City office. Portions of this work have been supported by 
an NSF Graduate Fellowship, NSF grant DEB 78-02069 (T. W. 
Schoener, principal investigator), NSF grant DEB 82-07052, and an 
Arizona State University Faculty Grant-in-Aid. 
