POLYMORPHISM AND DIVISION OF LABOR IN THE 
DACETINE ANT ORECTOGNATHUS VERSICOLOR 
(HYMENOPTERA: FORMICIDAE)* 
By Norman F. Carlin 
Department of Organismic and Evolutionary Biology, 
Harvard University, Cambridge, Mass. 02138 
Introduction 
The ants of the myrmicine tribe Dacetini exhibit a primary 
evolutionary trend from primitive epigaeic and subarboreal foragers 
to advanced cryptobiotic forms; in association with this trend are a 
number of secondary tendencies, including reduction in body size 
and mandible length, increasing specialization on collembolan prey, 
and loss of worker caste differentiation (Brown and Wilson 1959). 
The subarboreal and impressively long-mandibulate subtribe Orec- 
tognathiti, comprising the genera Orectognathus and Arnoldidris, 
occupies an intermediate position between the primitive polymor- 
phic genus Daceton and the largely monomorphic higher subtribes 
Epopostrumiti and Strumigeniti. All but one of the twenty-nine 
known species of Orectognathus are monomorphic, the exception 
being O. versicolor , which possesses a distinctive major caste 
(Taylor 1977, 1979). Caste differentiation in this species is con- 
sidered to have evolved secondarily, from the monomorphic generic 
stock (Brown and Wilson 1959). 
The extreme polymorphism of Daceton armigerum, the only 
lower dacetine whose behavior has been studied, is put to work in an 
equally extreme division of labor (Wilson 1962). The minor workers 
are strictly limited to brood care tasks (in which they are aided by 
callows of larger castes), and to regurgitation with other adults. 
Small medias forage widely and actively, but larger medias and 
majors tend to rest in “way-stations” some distance from the nest. 
These large workers take prey away from returning smaller foragers, 
bringing it into the nest themselves, so that little prey is carried back 
by those that hunt for it. The species takes a broad variety of prey 
items; it has been suggested that the dietary specialization on 
collembolans seen in higher dacetines might account for their 
♦Manuscript received by the editor December 1, 1981. 
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