Molecular Studies of the Bionectriaceae Using Large Subunit rDNA Sequences

Abstract

Holomorphic species of fifteen genera in the family Bionectriaceae, Hypocreales, and related anamorph species were studied using nuclear large subunit rDNA sequences. Most elements of the Bionectriaceae are shown to form a monophyletic group closely related to representatives of two other families in the Hypocreales, namely the Clavicipitaceae/Hypocreaceae, which is distinct from the Nectriaceae. The genus Bionectria, represented by B. ochroleuca and its anamorph, Clonostachys rosea, and B. cf. aureofulva, appears as a monophyletic lineage that groups with three other species that may also belong to Bionectria. The Bionectria clade is distinct from a second major lineage that includes the perithecial genera Hydropisphaera, Nectriopsis, Ochronectria and Selinia, as well as two cleistothecial genera, Heleococcum and Roumegueriella. Within this lineage the cleistothecial genera, Heleococcum, represented by the nontype species, H. japonense, and the monospecific genus, Roumegueriella, group with the paraphyletic genus Hydropisphaera, including H. peziza, the type species, and H. erubescens. Another lineage includes six cleistothecial genera, namely Bulbithecium, Emericellopsis, Hapsidospora, Leucosphaerina, Mycoarachis, and Nigrosabulum, most of which have Acremonium anamorphs. These genera cluster with the type of Acremonium, A. alternatum, and two anamorph genera, Geosmithia, and Stanjemonium. Both species of Kallichroma, K. tethys and K. glabrum, form a separate lineage within the Bionectriaceae. Kallichroma is the first genus from marine habitats to be confirmed as a member of the Hypocreales. Although classified in the Bionectriaceae based on morphological evidence, species of the tropical genus Peethambara and their Didymostilbe anamorphs and the morphologically similar anamorph genera, Albosynnema and Myrothecium, fall outside of any of the supported clades. These species form a paraphyletic group at the base to the Hypocreaceae/Clavicipitaceae.