NATURAL HISTORY OF THE WORKERLESS 
INQUILINE ANT POGONOMYRMEX COLEI 
(HYMENOPTERA: FORMICIDAE)* 
By Steven W. Rissing 
Department of Zoology 
Arizona State University 
Tempe, Arizona 85287 
At least 10 workerless inquiline ant species are known from North 
America (Francoeur 1968, 1981; Wilson 1971, 1976; Talbot 1976; 
Buschinger 1979; DuBois 1981; Snelling 1981), most only from 
original collections. In this paper I present field and laboratory 
observations of Pogonomyrmex colei Snelling a new, apparently 
workerless, inquiline ant inhabiting a colony of Pogonomyrmex 
rugosus. 
P. colei appears to be a very rare species: extensive searching of 
the type locality for 4 yr has resulted in discovery of only a single 
colony. Nonetheless, observations on this colony provide insight 
into several important aspects of inquiline ant biology. P. colei is 
also of interest since it is the second apparently workerless con- 
generic inquiline inhabiting colonies of P. rugosus. Cole discovered 
the first inquiline species, Pogonomyrmex anergismus, near Silver 
City, New Mexico apparently prior to any major flight since he 
exposed “more than one hundred” inquiline reproductives upon 
opening the host nest (Cole 1954, 1968). Since host species mating 
flights occur soon after rain during mid to late summer (Holldobler 
1976; Rissing personal observation), it seemed reasonable to suspect 
P. anergismus responds to the same environmental cues for mating 
as does its host. Accordingly, in an effort to rediscover P. anergis- 
mus, I routinely checked most P. rugosus nests on a 25 ha study area 
in Boulder City, Nevada for flight activities and possible presence of 
inquilines during late summer 1978 and 1979 (study area described 
in Rissing 1981). P. colei was discovered during this effort. 
* Manuscript received by the editor June 7, 1983 
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