THE FIRST WORKERLESS PARASITE IN THE 
ANT GENUS FORMICA (HYMENOPTERA: 
FORMICIDAE) 
By Edward O. Wilson 
Museum of Comparative Zoology, Harvard University, 
Cambridge, Massachusetts 02138 U.S.A. 
Abstract. Formica talbotae Wilson, a member of the microgyria group and 
the first proven workerless parasite in Formica, is described here. The species is 
known from Michigan, Iowa, and North Dakota. The discovery of talbotae com- 
pletes the inferred evolutionary progression within Formica from independent 
existence through temporary parasitism to permanent, workerless parasitism. 
During her exhaustive survey of the ant fauna of the Edwin 
S. George Reserve of Michigan, an effort previously unparalleled 
in North America, Mary Talbot has uncovered a surprising num- 
ber of rare and undescribed species. One of the most significant 
is the species to be described below, a member of the Formica 
microgyria group which to the best of my knowledge is the first 
adequately documented example of a workerless parasite in this 
large Holarctic genus. 
Formica talbotae Wilson, new species 
Diagnosis {queen). A small species even for the microgyna 
group, characterized further by the following combination of 
traits: subquadrate head; smoothly rounded anterior clypeal 
border; thick petiolar node with relatively thick, rounded crest; 
short (0.05-0.08 mm), dense standing pilosity over all of body 
and appendages, including scape; many of the hairs on the tho- 
racic dorsum, propodeum, petiole, and fore coxae spatulate. 
So far as known, talbotae is exclusively a workerless parasite 
of Formica obscuripes Forel. 
Relationships. During the study I examined specimens of all 
of the microgyna group species for which sexual forms are known. 
Most of those known from workers solely were also examined, 
but are in any case considered probably distinct on the basis of 
the possession of a worker caste alone. The closest species is F. 
dirksi Wing, which differs in the queen caste by its slightly lar- 
ger size; much longer, less frequently spatulate pilosity; and more 
rounded head shape. F. spatulata Buren is also close but its queen 
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