<i>Peziza nivalis</i> and relatives—spring fungi of wide distribution

Several members of the genus <i>Peziza</i> sensu stricto occur at the edge of melting snow. These nivicolous species have been widely reported in the Northern Hemisphere and are also known from Australia and New Zealand. We have used 16 specimens from North America and Australia to study morphology and to perform DNA sequencing. In sequence analyses, we have used ITS1 and ITS2 (internal transcribed spacers), 28S, <i>RPB2</i> (RNA polymerase II gene), and two genes new to these studies, <i>GAPDH</i> (glyceraldehyde-3-phosphate dehydrogenase) and <i>HSP90</i> (heat shock protein 90). Although not all regions are available for all samples, we have recognized the following species: <i>Peziza heimii, P. nivalis</i>, and <i>P. nivis</i>. Phylogenetic analyses were done using ITS alone; combined ITS1-5.8S-ITS2, 28S, and <i>RPB2</i>; ITS, and 28S, <i>RPB2, GAPDH</i>, and <i>HSP90</i>. Even with this augmented set of genes and despite their widespread occurrence in North America, Europe, Australia, and New Zealand, we have not definitively distinguished species within this group. To assess these results, pairwise homoplasy index (PHI) analysis was employed. This showed evidence of recombination among the samples of <i>P. nivalis</i> and further supports the view of <i>P. nivalis</i> as a monophyletic cosmopolitan species. As part of this study, we also examined the variation in ITS copies in <i>P. echinospora</i>, for which a genome is available.