1984] 
Wheeler — Behavior of Proeryptoeerus 
187 
When the relative importance of characters is considered, clado- 
gram A gains plausibility over B. The ability to stridulate has rarely 
been lost in the Myrmicinae (Markl, 1973). Therefore, a single loss 
(cladogram A) can be considered more likely than a double one 
(cladogram B). Similarly, abdominal grooming movements occur in 
almost all ants (Wilson, 1962; Farish, 1972); loss is probably a rare 
evolutionary event. The appropriate pattern of abdominal groom- 
ing is derived most parsimoniously in cladogram A. Adult transport 
(carrying) on the other hand is a character expressed to widely 
varying degrees among the ants. Nestmate carrying, used primarily 
during emigration to new nest sites, may be relatively easy to lose if 
it becomes unnecessary ecologically. The adult transport character 
then does not lend strong support to either cladogram. Finally, the 
appropriate pattern for abdominal trophallaxis is derived most par- 
simoniously in cladogram B. In cladogram A, Cephalotes loses this 
character secondarily. Since intraspecific abdominal trophallaxis 
rarely occurs in ants, and is poorly understood, the difficulty or ease 
of its subsequent loss cannot be evaluated. In summary, on the basis 
of a character by character evaluation, cladogram A is more 
plausible. 
Implications for the Evolution of Worker Polymorphism 
Monomorphism is the ancestral state of the worker caste in most 
ants and probably represents the ancestral state of the Cephalotini 
as well. In myrmicines, a few cases of secondary monomorphism are 
known in species with workers that are minute in comparison to the 
queen (Wilson, 1953, 1971). If worker monomorphism is accepted 
as the ancestral state in the Cephalotini, then cladogram A provides 
the most parsimonious derivation of the pattern of worker poly- 
morphism. Cladogram B implies that the morphological worker 
caste systems characteristic of Zacryptocerus and Cephalotes 
evolved independently. According to cladogram A, the tendency to 
express morphological diversity within the worker caste evolved 
once. Cephalotes maintained a weak bimodality in the size fre- 
quency distribution over a wide size range (Corn, 1980), while the 
Zacryptocerus line intensified that bimodality, a trend which led to 
the completely dimorphic worker caste of some species. 
If worker monomorphism is ancestral and Proeryptoeerus repre- 
sents a relict state, it follows that, in the Cephalotini, soldiers must 
