Phylogeny of the genus Plicaria and its relationship to Peziza inferred from ribosomal DNA sequence analysis

Controversy exists as to whether Plicaria, which has spherical spores, should be maintained as a separate genus from Peziza, which has elliptical spores. The objectives of this study were to determine if Plicaria represented a phylogenetic grouping of taxa distinct from Peziza, and to clarify Plicaria species concepts. To determine phylogenetic relationships, DNA sequences were obtained from the 5' Internal Transcribed Spacer region, the divergent domains D1 and D2 of the 28S gene, and a region near the 5' end of the 18S gene of the nuclear-encoded ribosomal DNA. We also examined ascospore ornamentation using scanning electron microscopy. Analysis of spore morphology and molecular characters revealed that the smooth spored Plicaria endocarpoides and the rough-spored Plicaria trachycarpa, Plicaria carbonaria and Plicaria acanthodictya could be distinguished. Parsimony analysis showed that Plicaria forms a monophyletic group. However, several Peziza taxa that share a number of morphological characters with Plicaria are closely related. We suggest that Plicaria be recognized as a separate genus, although Peziza is paraphyletic if Plicaria is maintained.