no. 3616 GENUS EUPARIXIA — WOODRUFF AND CARTWRIGHT 3 



certainly exclude them as accidental. They have been found in the 

 active fungus gardens and in detritus chambers (pi. 2: fig. 2), which 

 consist of old fungus and debris discarded by the ants. It is rather 

 unlikely that they feed on the fungus grown by the ants (pi. 1 : fig. 2) 

 since no other members of the subfamily Aphodiinae are known to 

 have this habit. If they actually fed on the fungus, competing with 

 the ants, it would be likely that they would occasionally be thrown 

 out of the nest. This has not been observed. All of the species 

 except E. costaricensis (known from the unique type with incomplete 

 data) and E. moseri, new species, have been collected at lights and 

 possess fully developed wings. 



The behavior of Euparixia within the nests has not been observed, 

 and no evidence is available to determine if they are synechthrans 

 (unwelcome guests), synoeketes (unnoticed or tolerated guests), or 

 symphiles (true guests). The latter classification would seem most 

 likely, but many diligent hours of observation will be necessary to 

 determine the true role of Euparixia. Cazier and Statham (1962) 

 and Cazier and Mortenson (1965) have made numerous observations 

 on the myrmecophilous scarab genus Cremastocheilus and in at least 

 one case, C. stathamae Cazier, the adult beetles were found to be 

 obligatory predators on the ant larvae. We have no evidence for 

 similar habits in Euparixia. Moser (pers. comm.) believes that the 

 adult, at least, is tied to the ecology of the fungus garden, since all 

 but one of the specimens have been collected in this niche. The 

 numerous species of inquilines associated with detritus cavities are 

 practically never found in fungus gardens. 



Certainly many ecological factors are unique in the complicated 

 and extensive underground passages of these fungus-growing ants. 

 Wheeler (1900, p. 855) postulated that the vast amounts of com- 

 minuted and decomposing vegetable matter collected by the ants as 

 a soil or culture medium for their fungus would be a favorable resort 

 for numerous myrmecophiles. Walter, Seaton, and Mathewson 

 (1938) record approximately 50 species of insects and arachnids 

 found within the nests in association with Atta texana at San Antonio, 

 Tex. They record two scarabs in the subfamily Cetoniinae but no 

 members of the genus Euparixia or the subfamily Aphodiinae. Moser 

 (1963) has found a considerable number of interesting myrmecophiles 

 in his studies of the biology and ecology of this ant in Louisiana (some 

 of these have been described by Sabrosky, 1959; Spangler, 1962; 

 and Chillcott, 1965). 



Weber (1958, p. 459) stated that the true culture of fungi is con- 

 fined to the New World ants of the tribe Attiini, all known species 

 of which are dependent on fungus gardens for food. The genus 

 Atta is considered to be the most highly developed in the tribe, in 



