PSYCHE 
VOL. XXXVI MARCH, 1929 
No. 1 
THE IDENTITY OF THE ANT GENERA GESOMYRMEX 
MAYR AND DIMORPHOMYRMEX 
ERNEST ANDRE. 1 
By William Morton Wheeler 
During the examination of a considerable number of ants 
collected by Dr. L. G. K. Kalshoven in the teak-forests of Java, 
I have come upon an undescribed species of Gesomyrmex, 
represented by a graded series of workers, all taken from a 
single colony and demonstrating that the singular Formicine 
genera Gesomyrmex and Dimorphomyrmex are synony- 
mous. I have long surmised this identity, because there are 
no significant differences among the worker phases, except 
in the proportions of the head, eyes, clypeus, frontal carinse 
and mandibles. Even the antennae are the same and consist 
of only 8 joints in the worker, instead of 12, which is the 
number observed in the great majority of Formicidae. But 
hitherto so few specimens of the two genera have been seen 
and the sexual forms have been so imperfectly known that 
no definite statements could be made in regard to their 
affinities. 
Gesomyrmex was established sixty years ago (1868) 
by Mayr for a peculiar, large-eyed ant, G. hoernesi, which he 
found in the Baltic amber, of Lower Oligocene Age. In 1892 
Ernest Andre described two extant species of ants taken by 
Chaper in the Kapoewas Basin, North Borneo. One of them, 
which he called G. chaperi, was evidently very closely related 
to the amber form ; for the other, which was larger and had 
a much larger and more rectangular head and smaller eyes, 
he erected a new genus, Dimorphomyrmex. This form, 
Dimorphomyrmex janeti, he described as possessing dimorphic 
iContributions from the Entomological Laboratory of the Bussey 
Institution, Harvard University No. 308. 
