Polyphyletic origins of yeast-like endocytobionts from anobiid and cerambycid beetles

Cladistic analysis of nucleotide characters derived from partial 18S rDNA s equences has been used to infer phylogenetic relationships among five Candi da species that exist in nature strictly as intracellular gut endocytobiont s of anobiid or cerambycid beetles. Concordant with their assumed taxonomic status, all five species resolve within Saccharomycetales. For both the an obiid-derived taxa, C. ernobii, C. karawaeiwii and C. xestobii, and the cer ambycid-derived taxa, C. tenuis and C. rhagii, this phylogenetic position c learly discriminates Candida yeasts from the anobiid yeast-like endocytobio nts in Symbiotaphrina which resolve within filamentous ascomycetes. The ana lyses provide no evidence for a discrete lineage of Candida endocytobionts within Saccharomycetales. Rather, each of the anobiid symbionts and the cer ambycid-derived species resolve in separate clades. These data confirm the polyphyletic origins of intracellular symbioses between ascomycetes and Col eoptera and provide another example of convergent evolution in fungal-arthr opod associations. The implications of the phylogenetic data for theories o n the origins of endocytobiosis are discussed.