A novel basidiomycetous yeast was isolated from the waste deposit of the attine ant Acromyrmex lundii (Hymenoptera: Formicidae). The field colony was located in Santurce town, Santa Fe province, Argentina. The description of the novel species was based on strain LLU043T. Analysis of the D1/D2 domains of the LSU rRNA gene sequences in GenBank demonstrated that strain LLU043T, belongs to the Rhodosporidiobolus clade and is closely related to Rhodosporidiobolus lusitaniae and Rhodosporidioboluscolostri with 97 % similarity to the two species. The novel species differs from R. lusitaniae and R. colostri in some physiological characteristics such as the lack of assimilation of cellobiose, salicin, succinate, citrate and ethylamine. The name Rhodosporidiobolus geoffroeae sp. nov. is proposed, with LLU043T (=CBS 12828T=CBMAI 1618T) as the type strain.