YEASTS ASSOCIATED WITH TERMITES - A PHENOTYPIC AND GENOTYPIC CHARACTERIZATION AND USE OF COEVOLUTION FOR DATING EVOLUTIONARY RADIATIONS IN ASCOMYCETES AND BASIDIOMYCETES

Thirtynine yeast isolates or dimorphic fungi were obtained from the hi ndgut of the lower termites Mastotermis darwiniensis (Mastotermitidae) , Zootermopsis angusticollis, Z. nevadensis (Hodotermitidae), Neoterme s jouteli (Kalotermitidae), Reticulitermes santonensis, Heterotermes i ndicola (Rhinotermitidae) and the roach Crptocercus punctulatus. Using RAPD-PCR the 39 yeast isolates were assigned to 13 different species. Commonly yeast species were specific to the termite species isolates from. There were only two yeast species which were found in different species of lower termites. Based on phenotypic characters Debaryomyces hansenii showed a high score in four species. The qualitative and qua ntitative yeast cell wall monosaccharide composition, the ubiquinone s ystem, partial sequencing of 18S ribosomal DNA (bases 1273 to 948; num bering according to the gene of Saccharomyces cerevisiae), and the ult rastructure of septal pores indicate that 11 yeast species belong to t he Endomycetales. Although ascospores were lacking, two of these speci es were identified to belong to the genus Debaryomyces. One remaining yeast isolate was identified as a Sporothrix anamorph representative f or the filamentous Ascomycetes (Ophiostomataceae s. str.); the second species showed affinities to the Basidiomycetes in particular to the g enus Trichosporon. Comparing an additional 18S rDNA fragment (bases 59 5 to 993) and RAPD-PCR data using different species type strains of th e genus Sporothrix, the filamentous ascomycete was genotypically ident ified as Sporothrix albicans. Sporothrix. albicans, although phylogene tically closely related to S. schenckii var. schenckii and Ophiostoma stenoceras remains genotypically distinct. An emended species descript ion of S. albicans is presented. Evidence is provided that the yeasts isolated from the hindgut can be considered symbionts.