Genus of fungi
Tulasnella is a genus of effused (patch-forming) fungi in the order Cantharellales. Basidiocarps (fruit bodies), when visible, are typically smooth, ceraceous (waxy) to subgelatinous, frequently lilaceous to violet-grey, and formed on the underside of fallen branches and logs. They are microscopically distinct in having basidia with grossly swollen sterigmata (or epibasidia) on which basidiospores are formed. One atypical species, "Tulasnella aurantiaca", produces orange to red, gelatinous, pustular anamorphs on wood. Some species form facultative mycorrhizas with orchids and liverworts. Around 80 species of "Tulasnella" are known worldwide.
Taxonomy.
History.
"Tulasnella" was originally circumscribed by German mycologist Joseph Schröter in 1888, partly based on an earlier illustration by Charles Tulasne, after whom the new genus was named. Schröter believed the unusual basidia sufficiently distinct to warrant the creation of a new genus which he considered intermediate between "Sebacina" (then used for most effused "heterobasidiomycetes" with septate basidia) and "Thelephora" (then used for many effused "holobasidiomycetes" with conventional non-septate basidia). The genus was subsequently placed among the "heterobasidiomycetes" by most authors.
Between 1909 and 1928, French mycologists Hubert Bourdot and Amédée Galzin described more than a dozen new species of "Tulasnella" from collections made in France. In the USA, American mycologist D.P Rogers published a review of the "Tulasnellaceae" in 1933 in which he extended the definition of "Gloeotulasnella", originally established to accommodate cystidiate species, to include "all mucous forms", though "Gloeotulasnella" was subsequently considered synonymous with "Tulasnella" by most authors. Later, in Australia, Jack Warcup and P.H.B. Talbot described several new "Tulasnella" species isolated from orchid mycorrhizas. In 1987 American mycologist Royall T. Moore proposed the new genus "Epulorhiza" for anamorphic (hyphal) states of "Tulasnella" previously referred to the form genus "Rhizoctonia". In the UK in the 1990s, Peter Roberts described additional new species of "Tulasnella" and monographed the genus in a series of papers with a worldwide key to species. 
Current status.
Molecular research, based on cladistic analysis of DNA sequences, has confirmed "Tulasnella" as a distinct genus, but has placed it within the Cantharellales rather than in its own order the "Tulasnellales".
Following changes to the International Code of Nomenclature for algae, fungi, and plants, the practice of giving different names to teleomorph and anamorph forms of the same fungus has been discontinued, meaning that "Epulorhiza" has become a synonym of the earlier name "Tulasnella". As a result, existing anamorphic species have been transferred to "Tulasnella" and new anamorphic species have been described in this genus.
Molecular research has also shown that the anamorphic, pustular, wood-inhabiting genus "Hormomyces" is a synonym of "Tulasnella", not "Tremella" as previously thought.
An updated morphological key to species was published in 2016.
Association with orchids.
In 1899 French botanist Noël Bernard discovered that orchid seeds require a fungal associate to germinate and most if not all orchids maintain this mycorrhizal association with fungi throughout their lifecycle. In the 1960s, cultures derived from orchid mycorrhizas that were induced to form teleomorphs (fruit bodies) showed that "Tulasnella" species (together with "Rhizoctonia" species) were frequent associates of terrestrial orchids in Australia. Direct DNA sequencing of orchid mycorrhizas has confirmed this association on a global scale, for both terrestrial and epiphytic orchids. Most recently described anamorphic "Tulasnella" species have been isolated from orchid mycorrhizas, but many more await formal description.
Association with liverworts.
Molecular research has shown that thalloid liverworts in the family Aneuraceae associate frequently and perhaps exclusively with species of "Tulasnella", ether in a mycorrhizal or parasitic relationship.
Species.
Species currently accepted by Species Fungorum.
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Species currently regarded as synonyms by Species Fungorum.
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References.
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