4 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 123 



terms of biology, behavior, and morphology. Acromyrmex is con- 

 sidered to be nearest it on a phylogenetic basis. It is possible that 

 species of Euparixia or related genera might occur with other ant 

 genera in this tribe, namely Cyphomyrmex, Mycetophylax, Mycoce- 

 purus, Myrmicocrypta, Apterostigma, Sericomyrmex, and Trachy- 

 myrmex. The nests of few species of Atta or related genera have 

 been investigated thoroughly for inquilines. Certainly the complex 

 association between ants, fungus gardens, and beetles has taken 

 considerable time to evolve. Weber (1958, p. 460) postulated that 

 the South American tropical forests may have been the original home 

 of the attine ants and their fungi, and that this symbiosis may have 

 become established during a period nearly 50 million years ago. 

 Since most attine ants are presently found in South America, it would 

 be surprising if no eupariine scarabs occupied this niche on that 

 continent. 



Distribution, (fig. 1). — The distribution records for the few 

 specimens available indicate that the species of Euparixia are allo- 

 patric. It is highly probable that each species of beetle occurs with 

 only one species of ant, but the distribution probably is much more 

 extensive than presently known. The known distribution of the 

 five species of Euparixia is as follows : E. bruneri Chapin from Baragua, 

 Camaguey, and Santiago de las Vegas, Cuba; E. costaricensis Hinton 

 from an undetermined locality in Costa Rica; E. formica Hinton 

 from Tejupilco, Mexico; E. duncani Brown from southern Arizona 

 and northwestern Mexico; and E. moseri, new species, from south- 

 western Louisiana. 



Borgmeier (1959) lists 14 species of Atta, most of which occur in 

 South America but no Euparixia have been found there. Smith 

 (1963) summarizes the United States and Mexican distribution of 

 the genus Atta. Using the known distribution of the ants (fig. 1), 

 we can postulate the probable distribution of the myrmecophilous 

 Euparixia. E. bruneri Chapin probably occurs with A. insularis 

 Guerin throughout the island of Cuba although it has been found 

 only at two localities. E. formica Hinton has been recorded as 

 associated with A. sexdens (L.) (Hinton, 1934), which has the greatest 

 range of the species of Atta. It has been reported from Panama, 

 Colombia, Ecuador, Bolivia, Venezuela, Guiana, Surinam, Brazil, 

 Paraguay, Argentina, and Uruguay; however, it is not recorded from 

 Mexico and the records of Hinton (1934) for this host probably refer 

 to A. mexicana Frederick Smith, which is widely distributed in Mexico 

 and recorded from El Salvador and extreme southern Arizona. 

 A. cephalotes (L.) is recorded also from southern Mexico (Vera Cruz, 

 Cordova, and Oaxaca), Central America, Ecuador, Colombia, Ven- 

 ezuela, Peru, Bolivia, Guiana, and Brazil but not within the known 



