Heilmann-Clausen et al. (2017) reported Tricholoma roseoacerbum appearing to be remarkably widely distributed globally, with almost perfect ITS sequence matches connecting collections samples from Finland, Japan, Canada and environmental samples from Mexico. The conspecificity of European, American and Asian collections should be tested with more genetic markers, as should the populations in northern and southern Europe associating with pines and broadleaved trees respectively. Here it is treated as one taxon.

Tricholoma roseoacerbum is a rare fungus with an insufficiently understood ecology and oddly wide global distribution. It forms mycorrhiza with Pinus in dry, old-growth Pinus forests in northern Europe, and with with Picea, Castaea and Quercus in xerophilic forests in southern Europe. It also occurs in eastern Canada. Sequencing of environmental samples and sporocarp collections implies it is also present in Mexico and Japan. It is rare everywhere and Red Listed in multiple European countries where it has its centre of occurrence, predominantly in Fennoscandia, where the estimated number of localities is several hundred. The global population size is estimated to exceed 20,000 mature individuals. It is estimated to have declined and to be continuously declining in the boreal zone at a rate of 30-50% over 50 years (three generations) due to decreasing area of old-growth forests and an apparent poor ability to spread and re-establish after cutting due to its rareness. Taking into account the uncertainty of its ecology, distribution and overall status and trend, the global rate of decline is suspected to be in the range of 20-29% over three generations. T. roseoacerbum is, therefore, assessed as Near Threatened (A2c+3c+4c) based on the relation between potential area and quality of habitat and population size.

Tricholoma roseoacerbum is widespread in boreal and temperate Europe, but appears to be rare everywhere (Christensen and Heilmann-Clausen 2013). Most European records are from Fennoscandia (GBIF 2024). In Russia it is rare and only reported from Krasnoyarsk Krai (T. Svetasheva pers. comm). However, it appears to be remarkably widely distributed, with almost perfect ITS sequence matches connecting sporocarp collections and environmental samples from Finland, Japan, Canada and Mexico (Heilmann-Claussen et al. 2017). The associated map is incomplete.

Tricholoma roseoacerbum is a very rare species with a poorly understood ecology and global distribution. The major part of the known population is in Fennoscandia where it is estimated to be occurring in 200 localities in northern Sweden (SLU Artdatabanken 2020, GBIF 2024), possibly with a similar number of localities in Finland (see Hyvärinen et al. 2019). The number of individual mycelia seems to be small in the limited number of forests it occurs in. Although it is considered very rare in the remaining distribution, the total global population it is estimated to exceed 20,000 mature individuals (see Dahlberg and Mueller 2011).

In northern Europe, T. roseoacerbum is primarily threatened by clear-cutting of old-growth pine forests (see e.g. Svensson et al. 2019 from Sweden, Kotiaho 2017 from Finland). It is not reported to reappear in forests that regenerate after clear-cutting. The major part of the potential pine habitat is located in northern Europe and some parts of Russia. Around 1% of the forest is estimated to be cut annually. A conservative estimate of the potential decline of appropriate habitat is in the range of 30-49% in the boreal zone over a 50 year period (three generations, Dahlberg and Mueller 2011). Taking into account uncertainties of numbers, and size of subpopulations and rates of forest cutting in Russia, and elsewhere in its range, the overall population decline is suspected to be 20-29% over 50 years.

Tricholoma roseoacerbum forms ectomycorrhiza with Pinus in sandy or gravelly, dry, old-growth forests in the northern parts of Fennoscandia (Christensson and Heilmann-Clausen 2013, Nitare 2023). In southern Europe, it is reported to be associated with Picea, Castanea and Quercus in dry conditions (Christensson and Heilmann-Clausen 2013). It always shows a preference for xerophilic conditions. It is very rare everywhere with only scattered occurrences, typically only a few mycelia in a forest, if present. These mycelia are considered to be long-lived, potentially several decades to centuries (cf. Dahlberg and Mueller 2011). The almost perfect sequence match between soil samples from Mexico, sporocarps in Japan (named T. japonicum) and sporocarp collections from northern and southern Europe implies it to have a remarkably wide distribution and wide ecology (see Heilmann-Clausen et al. 2017).

In northern Europe, Tricholoma roseoacerbum is primarily threatened by clear-cutting of old-growth sandy pine forests (see e.g. Svensson et al. 2019 from Sweden, Kotiaho 2017 from Finland). It is not reported from forests regenerated after clear-cutting. The major part of the potential pine habitat is located in northern Europe and some parts of Russia. Around 1% of the forest is cut annually, and a conservative estimate of the potential decline of appropriate habitat is in the range of 30-49 % over a 50 year period (three generations, Dahlberg and  Mueller, 2011) taking into account uncertainties of numbers and size of subpopulations and rates of forest cutting in Russia.

The species is not used.

The subpopulations in Fennoscandia are nationally Red Listed as Near Threatened/Vulnerable (Hyvärinen et al. 2019, SLU Artdatabanken 2020). The population in Canada is assessed as apparently secure (NatureServe 2020). In southern Europe it is very rare and nationally Red Listed as Endangered in Austria and Switzerland and Data Deficient in Germany (Senn-Irlet et al. 2007, Dämmrich et al. 2016, Dämon and Krisai-Geithuber 2017). Further research is required on this species.