Proceedings of 

 the United States 

 National Museum ^^^ 



SMITHSONIAN INSTITUTION • WASHINGTON, D.C. 



A SYNOPSIS OF THE ATOPETHOLIDAE, A FAMILY 

 OF SPIROBOLOID MILLIPEDS 



By Richard L. Hoffman ^ and Barbara S. Orcutt* 



Introduction 



The Sonoran region of Mexico and southwestern United States is 

 inhabited by species of the milhped family Atopethohdae, a small 

 group of the order Spirobolida apparently endemic to North America. 

 Despite its relatively limited extent, the family has fallen over the 

 years into a state of progressively increasing confusion, wliich seems 

 to be the normal course of events in this class of arthropods. Since 

 the family Atopethohdae was defined in 1918, some of its genera have 

 frequently been listed in the Spirobolidae (a completely dissimilar 

 family), while perfectly typical genera of the latter group have 

 simultaneously been considered atopetholids. No serious attempt 

 has been made to study the male gonopods of any atopetholid species; 

 hence the systematic position of the family has never been established. 

 Still worse, several genera were so poorly proposed that they have 

 remained unidentifiable up to the present time, and have provoked 

 considerable confusion and synonymy. The value of the various tax- 

 onomic characters normally used has never been critically considered. 



At this time a complete and satisfactory revision of the family 

 Atopethohdae cannot be undertaken. Many of the species are known 



' Department of Biology, Virginia Polytechnic Institute, Blacksburg, Va. 

 » Department of Conservation, Cornell University, Ithaca, N.Y. 



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