Phylogenetic relationships and distribution of Karstenella (Pezizomycetes)

Authors: Hansen, Karen & Weber, Nancy S. & Landvik, Sara
Journal: Karstenia, Volume 48 (2008), Issue 1, pages 13-19.
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Key words: Karstenellaceae, Pezizales, cytology, LSU, SSU

Abstract: Phylogenetic analyses of partial SSU and LSU rDNA sequences confirm that Karstenella vernalis is a member of the Pezizales. Substantiating this, we definitively report that the asci of Karstenella are operculate. Karstenella vernalis has been reported only from the type locality in Finland; we expand its known distribution to North America (New Mexico). The inconspicuous ascomata of Karstenellaconsist of very thin, resupinate apothecia borne on a subiculum. Hypotheses of a close relationship with Pyronema (Pyronemataceae) or other highly reduced apothecial forms are rejected. Combined analyses show that Karstenella constitutes an independent lineage within a highly supported group of the lineages B (Morchellaceae–Discinaceae and Helvellaceae–Tuberaceae) and C (Ascodesmidaceae, Pyronemataceae, Sarcoscyphaceae and Sarcosomataceae), Caloscyphaceae and Rhizinaceae. This corroborates recognition of a monotypic genus and family of Karstenella. A possible sister group relationship with Caloscyphaceae and/or Helvellaceae–Tuberaceaeis suggested. The ascospores of Karstenella are shown to be bi- to multinucleate using DAPI staining. Excipulum structure and/or spore cytology support a shared origin with Caloscyphaceae and/or the Helvellaceae–Tuberaceae sublineage.Karstenella possesses the most reduced form of ascomata found so far outside lineages A (e.g. Ascobolaceae) and C (e.g. Ascodesmidaceae and Pyronemataceae).