Nova Hedwigia Vol. 93 issue 3–4, 395– 400 Article Stuttgart, November 2011 A new species of Zwackhiomyces (Xanthopyreniaceae, Ascomycota) growing on Austroparmelina from Australia Sergio Pérez-Ortega1*, Javier Etayo2, John A. Elix3 and Ana Crespo4 1 Museo Nacional de Ciencias Naturales, CSIC, c/ Serrano 1 15-dpo, E-28006, Madrid Spain. e-mail: [email protected] 2 Navarro Villoslada 16, 3° dcha., E-31003, Pamplona, S pain. email: [email protected] 3 Research School of Chemistry , Australian National University, Building 33, Canberra, A.C.T. 0200 Canberra, Australia. e-mail: [email protected] 4 Departamento de Biología Vegetal II, Facultad de Farmacia, Universidad Complutense, Plaza de Ramón y Cajal s/n, Ciudad Universit aria, E-28040 Madrid, S pain. e-mail: [email protected] With 1 figure Pérez-Ortega, S., J. Etayo, J.E. Elix & A. Crespo (2011): A new species of Zwackhiomyces (Xanthopyreniaceae, Ascomycota) growing on Austroparmelina from Australia. – Nova Hedwigia 93: 395–400. Abstract: The new species Zwackhiomyces sulcatus sp. nov. growing on Austroparmelina macrospora from Australia is described as new to science. This species represents the first lichenicolous fungus found growing on this recently described Southern Hemisphere parmelioid genus. The most important characters are discussed and compared to morphologically closely related species. Key words: Lichenicolous fungi, Ascomycota, taxonomy. Introduction The genus Zwackhiomyces Grube & Hafellner is characterized by the combination of the following characters: perithecioid ascomata, lack of ostiolar filaments, abundant branched and anastomosed interascal filaments, fissitunicate asci, a distinctive pigmentation of the peridial cells produced by a granular dark brown, K+ blackish pigment, and 1-septate, hyaline ascospores (Grube & Hafellner 1990). Together with the genera Collemopsidium Nyl., Didymellopsis (Sacc.) Clem. & Shear, Frigidopyrenia Grube and Pyrenocollema Reinke make up the family Xanthopyreniaceae (Ascomycota incertae sedis) (Lumbsch & Huhndorf 2010). © 2011 J. Cramer in Gebr . Borntraeger Verlagsbuchhandlung, Stuttgart, Germany www.borntraeger-cramer.de DOI: 10.1127/0029-5035/2011/0093-0395 0029-5035/2011/0093-0395 $ 1.50 395.