Phylogenetics of the Pezizaceae, with an emphasis on Peziza

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Abstract:

Phylogenetic relationships among members of the Pezizaceae were studied using 90 partial LSU rDNA sequences from 51 species of Peziza and 20 species from 8 additional epigeous genera of the Pezizaceae, viz. Boudiera, Iodophanus, Iodowynnea, Kimbropezia, Pachyella, Plicaria, Sarcosphaera and Scabropezia, and 5 hypogeous genera, viz. Amylascus, Cazia, Hydnotryopsis, Ruhlandiella and Tirmania. To test the monophyly of the Pezizaceae and the relationships to the genera Marcelleina and Pfistera (Pyronemataceae), 6 species from the families Ascobolaceae, Morchellaceae and Pyronemataceae were included. Maximum parsimony and maximum likelihood analyses of these sequences suggest that the Pezizaceae is paraphyletic, because the non-amyloid Marcelleina is nested within it. If Marcelleina were transferred to the Pezizaceae, then the family would be monophyletic. Although the Pezizaceae is traditionally characterized by amyloid asci, our results indicate that the amyloid reaction is a symplesiomorphy, which has been lost in some lineages, e.g., in those including Marcelleina and Cazia. Nodes deep in the tree could not be resolved, but 7 groups of species (I-VII) are generally well supported or present in all trees. Peziza species, which constitute the core of the family, are present in all groups except group III, confirming the non-monophyly of the genus. The analyses suggest that the other included genera of the Pezizaceae are all nested within Peziza, the placement of Iodophanus being unresolved. The morphologically distinct Peziza gerardii, which forms a clade with Marcelleina, appears to be the sister group to the rest of the Pezizaceae. Morphological features were studied and evaluated in the context of the phylogeny. Distinct types of ascus amyloid reactions were found to support different rDNA lineages, e.g., a distinct amyloid ring zone at the apex is a synapomorphy for group IV, an intense and unrestricted amyloid reaction of the apex is mostly found in group VI, and asci that are weakly or diffusely amyloid in the entire length are present in group II. Other morphological features, such as spore surface relief, guttulation, excipulum structure and pigments, while not free from homoplasy, do support the groupings. Anamorphs likewise provide clues to higher-order relationships within the Pezizaceae. Several macro- and micromorphological features, however, appear to have evolved several times independently, including ascomatal form and habit (epigeous, semihypogeous or hypogeous), spore discharge mechanisms, and spore shape. Parsimony-based optimization of character states on our phylogenetic trees suggested that transitions to truffle and truffle-like forms evolved at least three times within the Pezizaceae (in group III, V and VI). The 9 hypogeous species included are nested in lineages with epigeous pezizaceous taxa. Species with apothecia of various shapes and with forcible spore discharge are spread among all groups and the apothecium is suggested to be symplesiomorphic in the Pezizaceae. The results indicate that the apothecia forming Pezizaceae have given rise to at least 3 different forms of hypogeous ascomata without forcible spore discharge: ptychothecia, stereothecia and exothecia.

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479ppTimes Cited:46Cited References Count:164