102 
Psyche 
[June 
SUMMARY 
Oecophylla leakeyi Wilson and Taylor is described as a new species. 
It is from the Lower Miocene deposits of Mfwangano Island, Kenya, 
and is the first species of fossil ant described from Africa south of the 
Sahara. The type series, which contains worker subcastes, pupae, and 
larvae in all stages of development, is interpreted as comprising a 
colony fragment, the first ever recorded as a unit in the social insects. 
From statistical and morphological studies of the three-dimensional 
specimens it is concluded that the worker polymorphism conforms to 
the essential features that uniquely characterize the living Oecophylla 
species within the modern ant fauna. This constitutes direct evidence 
of the stability of a specific social system through a considerable period 
of time, i.e. 30 million years or longer. Other evidence is cited which 
suggests that the leakeyi colony also resembled the modern species of 
Oecophylla in that it nested arboreally in tropical rain forest. 
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