Pindara revisited - evolution and generic limits in Helvellaceae

Area of Science:

• Mycology
• Evolutionary Biology
• Molecular Systematics
• Fungal Taxonomy

Background:

• The Helvellaceae family within Pezizomycetes (Ascomycota) exhibits diverse apothecial forms, but its evolutionary history and generic boundaries remain unclear.
• Previous classifications struggled to resolve phylogenetic relationships and delimit genera due to limited molecular data and phenotypic ambiguity.

Purpose of the Study:

• To construct a robust molecular phylogeny of the Helvellaceae using extensive molecular characters and broad taxonomic sampling.
• To resolve evolutionary relationships, clarify generic limits, and re-evaluate the taxonomic status of problematic taxa within the Helvellaceae.

Main Methods:

• Phylogenetic analysis utilizing a large dataset of 4,299 base pairs from LSU rDNA, RPB2, and EF-1α gene regions.
• Inclusion of a wide range of representative taxa from the Helvellaceae and related groups.
• Comparative analysis of molecular data with morphological and developmental characteristics, including ascus development.

Main Results:

• The genus Helvella was found to be polyphyletic, with Helvella aestivalis forming a distinct clade with hypogeous genera Balsamia and Barssia.
• The ear-shaped genus Wynnella was reclassified as Midotis, and the hypogeous genera Balsamia and Barssia, along with H. aestivalis, were combined under Balsamia.
• The enigmatic Pindara terrestris was recognized as a distinct genus, and a new genus, Dissingia, was erected for the /leucomelaena lineage of Helvella.
• Dissingia exhibits asci arising from simple septa, contrasting with the ancestral crozier-based development found in most other Helvellaceae, indicating at least two independent evolutionary events of this trait.
• Helvella astieri was confirmed as a synonym of Helvella lactea.
• Underwoodia columnaris was identified as the sister lineage to the rest of the Helvellaceae.

Conclusions:

• The study provides a refined phylogenetic framework for the Helvellaceae, necessitating significant revisions in generic circumscription and taxonomic placement.
• Molecular data reveal complex evolutionary pathways, including polyphyly in Helvella and independent evolution of ascus development mechanisms.
• The findings contribute to a more accurate understanding of fungal diversity and evolution within the Pezizomycetes.