Abstract
We collected a resupinate fungus lichenized with filamentous Rhizonema cyanobacteria in Amami-Oshima Island, Japan. Microscopic observations and molecular phylogenetic analyses of both the basidioma and the lichenized thallus indicated affinities within Cyphellostereum, the first record of this basidiomycete genus from Japan. Its unique combination of structural characters and ITS rDNA sequences suggest a new species, described here as C. ushima. Light and transmission electron microscopic observations revealed tubular intracellular haustoria penetrating longitudinally within the cyanobacterial cells, a feature typically seen in the related genus Dictyonema, but unusual in Cyphellostereum. The generic circumscription of Cyphellostereum was therefore emended to include features of C. ushima and other recently described species that deviate from the conventional definition of the genus. Ultrastructural details of symbiont interactions are provided for the first time in this genus. We also succeeded in cultivating the fungus from hyphae regenerated from thallus fragments, and include a brief description of those results.TreeBASE reviewer access URL:http://purl.org/phylo/treebase/phylows/study/TB2:S28437?x-access-code=84d2007afb05bd743f34101ac2d97dac&format=html
Cyphellostereum Ushima Sp. Nov. (Hygrophoraceae, Agaricales) Described from Amami-Oshima Island (Kagoshima Prefecture, Ryukyu Islands), Japan, with Ultrastructural Observations of its Rhizonema Photobiont Filaments Penetrated Longitudinally by a Central Haustorium
