The phylogenetic position of selected lechenicolous fungi: Hobsonia, Illosporium, and Marchandiomyces

The genera Hobsonia. Illosporium, and Marchandiomyces include several commo n lichenicolous (lichen-inhabiting) species that have been taxonomically li nked in the past. These mitosporic genera are frequently misidentified beca use of a paucity of morphological characters, which has led to some confusi on about their relationships. We examined the phylogenetic positions of spe cies in these genera using complete sequences of the small subunit (SSU) an d internal transcribed spacer (ITS) ribosomal DNA (rDNA), and portions of t he mitochondrial (mt) SSU rDNA obtained from isolated cultures of freshly c ollected specimens. Phylogenetic analysis of the sequence data indicated th at Marchandiomyces corallinus and M. aurantiacus are closely related member s of a basidiomycete clade. In addition, the clade includes an undescribed non-lichenicolous species that is morphologically similar to M, corallinus. Another undescribed species with marchandiomyces-like sclerotia, appears t o be in a separate basidiomycete clade. The three recognized species of Hob sonia are unrelated, with H. christiansenii appearing to be a hypocrealean ascomycete closely related to a sample of Illosporium carneum. H. santesson ii an ascomycete of unknown affinity, and H. mirabilis a basidiomycete. The latter, a plant pathogen, is the type species of Hobsonia. The new generic names Illosporiopsis and Hobsoniopsis gene. nov. are described for the lic henicolous species H. christiansenii and H. santessonii, respectively, and the necessary new combinations made.