Phylogenetic positions of deep-sea hydrothermal fungi. This consensus tree includes environmental SSU rRNA sequences isolated from environmental ecosystems (phylotypes 1 to 9) and isolated cultures from the same samples (phylotypes 10 to 20), along with the closest known related SSU rRNA fungal sequences. The tree was constructed using the neighbor-joining algorithm. Bootstrap values of >50% are indicated at the nodes (estimated using 1,000, 500, and 50 iterations for the neighbor-joining [NJ], maximum parsimony [MP], and maximum likelihood [ML] analyses, respectively). Stars indicate the phylotypes considered new phylotypes. The scale bar indicates 0.1 change per position computed using the NJ-K2P model. The dotted lines indicate branches not recovered in all three analyses. Designations that begin with MV followed by a hyphen indicate isolates from MARVEL cruise samples (Mid-Atlantic Ridge), and designations that begin with HE followed by a hyphen indicate isolates from “HERO” cruise samples (East Pacific Rise) (Table 1). The cultures obtained from sample MV2E1 are MV-1c to MV-4c, MV-21c, MV-23c, MV-FS1c, and MV-FS3c; the cultures obtained from sample MV2E2 are MV-8c, MV-10c, MV-25c, and MV-FS4c; the cultures obtained from sample MV2E3 are MV-15c, MV-19c, MV-26c, and MV-27c; the culture obtained from sample H18E9 is HE-5c; the cultures obtained from sample H18E11 are HE-1c to HE-3c; and the culture obtained from sample H18E12 is HE-4c. In the Ascomycota, the terminal HE-1c and HE-3c cultures were not defined as new phylotypes since their phylogenetic affinities were unclear.