Mitospore stages of Disciotis, Gyromitra and Morchella in the inland Pacific Northwest USA.

Colonies of Costantinella species growing on soil, moss and woody debris in the autumn in the inland Pacific Northwest USA were established in culture. Five different mitospore taxa were distinguished based on colony color, presence or absence of setae and internal transcribed spacer region (ITS) rDNA amplicon size. Sequence data from the largest and second largest subunits of RNA polymerase II, translation elongation factor 1-α, D1 and D2 domains of nuclear large subunit rDNA and ITS were used to connect each of the distinct mitospore taxa to corresponding vernal-fruiting Pezizales, including Disciotis cf. venosa, Gyromitra cf. esculenta and three species of Morchella. Both meiospore and mitospore stages of Morchella brunnea and M. populiphila collected in spring and autumn within a meter of each other at two urban sites had identical multilocus haplotypes, providing evidence connecting the two stages of the life cycle. Among other Morchella mitospore stages collected, some had identical haplotypes to previously sampled meiospore stages, while others were distinct, possibly representing undescribed species. Mitospore isolates with sequences assigning them to Disciotis or Gyromitra had different haplotypes from meiospore stages occurring in the same area. Meiospore stages of Disciotis and Gyromitra sampled as part of the study were also genetically distinct from European collections of D. venosa and G. esculenta, indicating more diversity is present in these taxa than is reflected in the current taxonomy. The widespread occurrence of mitospore stages of these fungi suggests that the life cycles of morels, false morels and allied taxa are more complex than previously recognized.