Thaxterogaster tenuipes

A species with a revised name

The supplied catalogue lists Cortinarius tenuipes. Index Fungorum now accepts Thaxterogaster tenuipes (Hongo) Zhu L. Yang & Zi R. Wang. The basionym is Cortinarius claricolor var. tenuipes Hongo (1969); the familiar 1987 combination Cortinarius tenuipes (Hongo) Hongo is treated as invalid in the 2025 taxonomic revision. The older name is retained here as an alias because food and field guides use it.

The 2025 treatment ties the name to the Japanese holotype from Ōtsu, Shiga Prefecture, collected in 1954, and designates a sequenced epitype from Yunnan, China. Its description gives a pale yellow, sticky, plano-convex cap with fine pale fibrils, a whitish stem with basal mycelium and sometimes a faint violet tint, and small weakly ornamented spores. Those details explain the taxonomic work; they are not a safe field identification guide.

Japanese woodland and autumn records

Ishikawa Prefecture’s forestry guide lists the species under its old name as an autumn fungus of broadleaf woods. A Japanese technical guide describes fruiting on soil in oak woods, often in groups. A Miyagi regional picturebook records a specimen photo from Shichikashuku Town dated October 2010. Together these support regional Japanese autumn records; they do not establish a universal season or distribution.

The 2025 paper’s Yunnan epitype was collected on 10 August in a subtropical broad-leaved Fagaceae forest at 1,774 metres. That date is a single collection, not a repeatable fruiting season. The same paper points to different ecological and taxonomic sources but does not offer a food-use account for that locality.

What the edible labels mean

The FAO 2004 global annex lists Cortinarius tenuipes as edible, but supplies no country-level location for the entry. The annex explains that “edible” in its source compilation does not always mean a fungus is actually eaten; the category “food” requires a clear report. The word “global” describes the compilation, not proof that this mushroom grows or is eaten worldwide.

Ishikawa Prefecture’s guide marks the older name edible, and a Miyagi regional picturebook also gives an edible field-guide status. These are useful Japanese classifications. The sources reviewed do not provide a validated preparation method, species-specific toxicology, or evidence that would support a general safety recommendation.

Names, lookalikes and webcap hazards

The Japanese common name can overlap with the name of a poisonous mushroom. JATAFF explicitly cautions that local names are not enough to identify the specimen. It describes pale orange-brown caps, crowded gills that darken with age, a curved stem and cobwebby veil, but those observations should not be used as a recipe for determining a mushroom is safe.

Some Cortinarius relatives, including C. rubellus and C. orellanus, can cause severe kidney injury with delayed symptoms. Those sources do not claim that Thaxterogaster tenuipes contains orellanine. They do show why old names, folk names and broad resemblance are inadequate safety evidence. This page does not recommend gathering, tasting, cooking or eating wild specimens.

No documented fermentation method

The reviewed global classification and Japanese guides do not establish a fermentation or preservation method for this fungus. No fermentation use is documented. It should not be treated as a supported Fermentea fermentation ingredient, and no claim is made that cooking, drying, pickling or fermentation removes a wild mushroom hazard.