Pycnopulvinus aurantiacus gen. et sp. nov., a new sporocarp-forming member of Pucciniomycotina

Abstract

An unusual fungus producing minute orange stilboid sporocarps was found on a palm leaf mid-rib in a Neotropical forest. Morphological observations could not place this collection into any previously described species or genus and, due to an absence of sexual structures, even higher level placement was uncertain. Phylogenetic analysis of a portion of the large subunit and the internal transcribed spacer of the nuclear ribosomal DNA indicated that this fungus is related to Heterogastridium pycnidioideum and belongs to Heterogastridiales, Microbotryomycetes (Pucciniomycotina). A new genus and species, Pycnopulvinus aurantiacus, are proposed here to accommodate this fungus. Key wordsCeratocystis, Fungal biodiversity, litter fungi, palm fungi, Pycnobasidium, tropical mycology IntroductionThe majority of Pucciniomycotina (Basidiomycota) species have life cycles that include the production of microscopic fruiting structures (e.g., spermogonia of rust fungi), but only a few species within the subphylum form macroscopic fruiting bodies (Swann et al. 2001;Aime et al. 2014). Although these sporocarps vary in form (e.g., see Aime et al. 2014), many are stilboid or pycnidioid with spore masses produced at the base of the sporocarp and exiting through the tip of the neck. Fungi with such fruiting bodies can be found mostly in Atractiellomycetes (Oberwinkler and Bandoni 1982) and, as is true for many other members of Pucciniomycotina, little is known about their biology or biodiversity.