1985] 
Wilson — Dominican amber ants. 2 
15 
tion of West Indian biogeography. Army ants are among the least 
vagile of all social insects. Among the Ecitoninae of the New World, 
Neivamyrmex nigrescens has been recorded from the Islas Marias, 
100 km off the Mexican Pacific Coast, while A. klugi occurs on St. 
Vincent in the Lesser Antilles. No ecitonine is known farther away 
from the mainland, either from the northern arc of the Lesser 
Antilles or any of the Greater Antilles. Similarly, the Old World 
Dorylinae, represented by Aenictus, extends only as far east as the 
Philippine Islands, New Guinea, and Queensland (Wilson, 1964). It 
is wholly unknown from those portions of Micronesia and Polyne- 
sia that support a native ant fauna (Wilson and Taylor, 1967). The 
farthest outlier in the western part of the range is a population of A. 
fergusoni on Great Nicobar Island, 160 km from Sumatra. The 
existence of A. ectopus is therefore consistent with the common 
view based upon both geological and paleobotanical studies (Gra- 
ham and Jarzen, 1969) that the ancestral Greater Antilles were 
larger and extended closer to the Mexican mainland during the 
middle and late Tertiary than is now the case. 
Furthermore, the overall closer similarity of A. ectopus to con- 
temporary Mexican and United States species, although far from 
conclusive, is consistent with a closer approach of the Greater 
Antilles to Mexico than to the northern coast of South America 
during the Tertiary Period. 
Summary 
The first fossil army ant, Neivamyrmex ectopus, new species, is 
described from the Dominican amber, generally considered to be 
late Oligocene or early Miocene in age. Because of the extremely 
limited vagility of the Ecitoninae, and their apparent absence today 
from the West Indies north of St. Vincent, the presence of A. ecto- 
pus suggests a closer proximity of the Greater Antilles to the main- 
land during Tertiary times. Also, A. ectopus is phenotypically closer 
to species now living in Mexico and the southern United States than 
to the much richer Central and South American faunas. 
Acknowledgments 
I am grateful to F. M. Carpenter for making the photograph of 
the paratype worker and for advising me on techniques of preparing 
