''Uncobasidium luteolum'' is a species of

crust fungus The corticioid fungi are a group of fungi in the Basidiomycota typically having effused, smooth basidiocarps (fruit bodies) that are formed on the undersides of dead tree trunks or branches. They are sometimes colloquially called crust fungi or pa ...

in the family

Meruliaceae The Meruliaceae are a family of fungi in the order Polyporales. According to a 2008 estimate, the family contains 47 genera and 420 species. , Index Fungorum accepts 645 species in the family. Taxonomy The family was formally circumscribed by E ...

, and the type species of genus ''

Uncobasidium ''Uncobasidium'' is a genus of two species of crust fungi in the Meruliaceae family . The genus was circumscribed by mycologists Kurt Hjorstam and Leif Ryvarden in 1978 with the European fungus '' U. luteolum'' as the type species. The So ...

''. The holotype was collected in Øvre Dividal National Park, in Målselv Municipality (Norway), where it was growing on '' Salix''. The fungus has a monomitic hyphal system, with individual

hypha A hypha (; ) is a long, branching, filamentous structure of a fungus, oomycete, or actinobacterium. In most fungi, hyphae are the main mode of vegetative growth, and are collectively called a mycelium. Structure A hypha consists of one or ...

e measuring 2.5–4

μm The micrometre ( international spelling as used by the International Bureau of Weights and Measures; SI symbol: μm) or micrometer (American spelling), also commonly known as a micron, is a unit of length in the International System of Unit ...

and having a clamp connection and oily refractive contents. The basidia are four- sterigmate, measure 30–50 by 8 μm, and feature a hook-shaped protuberance. Its spores are

ellipsoid An ellipsoid is a surface that may be obtained from a sphere by deforming it by means of directional scalings, or more generally, of an affine transformation. An ellipsoid is a quadric surface; that is, a surface that may be defined as the ...

to obovate in shape, measuring 9 by 6 μm. '' Uncobasidium roseocremeum'', found in South America, differs microscopically from ''U. luteolum'' in its larger, spherical spores, and the presence of encrusted hyphidia.

References

Meruliaceae Fungi described in 1978 Fungi of Europe Taxa named by Leif Ryvarden Fungus species {{Polyporales-stub