1962] 
Bush — Genus Anastrepha 
99 
niques, have eliminated many arguments against inclusion of cyto- 
logical data in taxonomic studies. Cytological information in many 
cases offers the taxonomist who is interested in establishing better 
phylogenetic relationships a tool which can often supplement and 
strengthen his conclusions based on morphological data, as well as 
provide information not available by any other means. In the family 
Tephritidae this seems particularly true. 
Summary 
The karyotypes of nine species of Anastrepha (Tephritidae, 
Diptera) are described on the basis of mitotic metaphase morphology. 
The species include A. ludens, A. fraterculus , A . distincta, A. mom- 
binpraeoptans, A. zuelaniae , A. spatulata, A . striata , A. serpentina , 
and A. aphelocentema. All species have a diploid number of 12, with 
the exception of the males of A. serpentina where an X x X 2 Y sex 
determining mechanism resulted in a diploid number of n. Only 
six of the nine species investigated could be identified on the basis 
of chromosome morphology. It is suggested that A. distincta , A. 
mombinpraeoptans , and Mexican A. fraterculus , which have cyto- 
logically indistinguishable karyotypes, as well as A. ludens, A. 
zuelaniae, and the Brazilian form of A. fraterculus may represent 
part of a chromosome complex within the genus Anastrepha. The 
differences between the karyotypes of the Brazilian and Mexican 
populations of A. fraterculus, along with differences in external 
morphology and biology, suggest that these two forms may repre- 
sent sibling species. In general, it is concluded that the metaphase 
chromosomes of the family Tephritidae can be used for critical cyto- 
taxonomic and phylogenetic studies. 
Acknowledgements 
1 would like to express my appreciation to Srs. F. E. Guiza, M. 
Aguilar, and J. Ramirez for their assistance in rearing and main- 
taining field collections and laboratory populations during the course 
of this study. I wish also to express my gratitude to Drs. R. H. Foote, 
M. S. Wasbauer, and Messrs. F. L. Blanc and E. G. MacLeod 
for reading and discussing the manuscript with me. I would par- 
ticularly like to thank Dr. Kenneth W. Cooper, Dartmouth College 
Medical School, for his critical review and helpful comments con- 
cerning various aspects of this work. 
