Bryorutstroemia (Rutstroemiaceae, Helotiales), a New Genus to Accommodate the Neglected Sclerotiniaceous Bryoparasitic Discomycete Helotium fulvum

The new genus Bryorutstroemia is established for the red-brown, stipitate, bryoparasitic discomycete Helotium fulvum Boud. Combined phylogenetic analysis of ITS and LSU rDNA and EF1α revealed that Bryorutstroemia fulva belongs to the sclerotiniaceous clade, which comprises the paraphyletic families Rutstroemiaceae and Sclerotiniaceae. Bryorutstroemia formed with Clarireedia a supported clade (Rutstroemiaceae s.l.), though with high distance. Bryorutstroemia closely resembles other Rutstroemiaceae in having uninucleate ascospores with high lipid content and an ectal excipulum of textura porrecta, but is unique because of its bryophilous lifestyle and is extraordinary with its thick-walled inamyloid ascus apex. Although B. fulva was described in 1897, very few records came to our notice. The present study summarizes the known distribution of the species, including 25 personal collections from the years 2001–2022. Bryorutstroemia fulva was most often encountered on Dicranella heteromalla, and rarely on other members of Dicranales or Grimmiales, while inducing necrobiosis of the leaves. A detailed description based on mainly fresh apothecia is provided together with a rich photographic documentation. Six new combinations are proposed based on our phylogenetic results and unpublished personal morphological studies: Clarireedia asphodeli, C. calopus, C. gladioli, C. henningsiana, C. maritima, and C. narcissi.