Clarifying the identity of marketed edible Huotanjun (Burnt Charcoal Mushroom) in southern China

Huotanjun (Burnt Charcoal Mushroom) is a group of edible mushrooms widely hunted and eaten in southern China. Taxonomically, they belong to Russula sect. Nigricantinae. Confusion with the fatal Russula subnigricans cause many poisoning incidents in Asia. For a long time, European names were used in Asia but the Asian genotypes are not the same as European species. We studied specimens collected in the field or bought from markets in southern China. Analysis of four DNA loci (ITS, nc LSU, TEF1-alpha, RPB2) showed that, except for a specimen of Russula adusta from subalpine Abies forest in southwestern China, all the specimens represent species different from European and North American ones, suggesting prevalent continental endemism in this group. Four new species are here described. Among these, Russula sinoadusta and R. zhuzuijun are Asian counterparts of European R. adusta; R. brunneocystidiata and R. huotanjun are closely related and morphologically highly similar to European R. densifolia and R. fuliginosa. Using multi-locus data, we were able to establish the phylogenetic position of R. subnigricans. It is nested in R. sect. Nigricantinae and sister to R. latolamellata, a species also having distant lamellae and only reddening context. Except for R. sinoadusta which is known only from China, all of our other species are shared by China and Japan. We analyzed the presence/absence of the diagnostic toxin of R. subnigricans cycloprop-2-ene carboxylic acid for 12 species and did not detect the polymeric products in any of them but R. subnigricans. Nevertheless, considering the fact that several potentially edible species share the spaced lamellae and only reddening discoloration with R. subnigricans, we strongly recommend to only eat species with decidedly blackening context and gills.

Automated summary

This study focuses on the edible mushroom group known as Huotanjun in southern China, which is different from European and North American species. The research identifies four new species and establishes the phylogenetic position of the potentially fatal Russula subnigricans. The study also recommends caution when consuming mushrooms with similar characteristics and advises to only eat species with a blackening context and gills.