1985] 
Pamilo, Crozier, & Fraser — Rhytidoponera 
231 
tional though deciduous wings) and ergatogynes (queen-worker 
intermediates) is useful as a description of significantly-different 
biologies for the egg-layer role, and the mated workers we have 
discussed represent a third important type. We concur with the 
felicitous term of gamergate proposed for them by Peeters and 
Crewe (1984). 
The factors leading a Rhytidoponera worker to become a gamer- 
gate or not are unknown. Peeters and Crewe (1984) found percen- 
tages of gamergates much higher for Ophthalmopone (up to 63%) 
than reported for Rhytidoponera, and suggested that the wide vari- 
ability of this percentage during the year indicates that the determi- 
nation of gamergates in Ophthalmopone is purely a matter of 
whether or not males are available during a crucial period during 
the early period of a worker’s life. This idea remains to be tested for 
Rhytidoponera, but a major difference between the two genera is 
already known: a majority of Rhytidoponera workers have ovarian 
activity, whereas only gamergates possess oocytes in Ophthalmo- 
pone. Gamergates in both genera, however, are similar in being 
found in the nest and not outside. 
Foraging appears to be a rudimentary type-II type in the classifi- 
cation of Oster and Wilson (1978: 248-251): workers diffuse out from 
the nest and mostly act individually, but are capable of at least 
short-range recruitment when difficult food items are located. Con- 
certed defense of territory is lacking, although a kind of “defense in 
depth” operates: the further workers penetrate into the foraging 
areas of neighboring colonies, the more likely they are to encounter 
workers from these colonies and undergo potentially-deadly com- 
bat. However the density of ants is not high enough to make such 
contact invariable, and this is reflected in the fact that many forag- 
ing trips approach or exceed the line subtended by neighboring 
nests. Nevertheless, we would expect that workers would tend to 
avoid areas heavily patrolled by hostile ants, although the data are 
not numerous enough to test this hypothesis. 
The finding that foragers tend to choose the same direction in 
repeated trips is consistent with our expectation that the worker 
force would tend to avoid areas patrolled particularly heavily by 
those of neighboring nests, in that such a capacity for recollection is 
needed for the avoidance mechanism to operate. Foraging direction 
fidelity of the same kind as in R. sp. 12 has also been demonstrated 
