Extremely rare, very large and characteristic Tricholoma.

-16 records in NA
-2 in NY 1983, 1911; one in Mass 1911, one in Connecticutt 1916, four in NC 1918 twice, 1926, 1938; four times in Quebec 1995, 1996 and 2010 in two localities.
-3 recent new collections in NH and Mass
-one record in Italy but not confirmed by mycologist
-very large characteristicTricholoma, easy to identify
-in USA, it was found in many areas that have been deforested and this species may have extirpated from its southern USA AOO before 1950 as southern areas have been extensively surveyed by mycologists like Petersen and Vilgalys in the last 40 years without any new reports.

With reports from only 4 localities since 1980 for this large, distinctive and easy to identify species, we believe it is now identified when collected. 
Found in 4 localities worldwide, but the number of localities may be up to 50 times higher, so we estimate is to be found in 200 localities. This estimate corresponds to 400 genetically unique mycelia. The number of ramets are expected to be 2-3 times higher due its observed field presence, so total number of individual worldwide is estimated to be 1200.

This small population qualifies it for Near threatened (NT) under criterion D1.

A mycorrhizal fungi found on calcarous soils in northeastern mixed hardwood forest in USA or the southern Québec hardwood forest under oak, beech and hemlock.

This species is a mycorrhizal fungus species so it is dependent on living host trees for population viability. This mutually beneficial symbiotic association between fungus and plant host roots conveys numerous critical advantages for plant host survival. Mycorrhizal fungi are essentially the uptake organs for many nutrients i.e., nitrogen, phosphorus, numerous micronutrients, i.e., boron, selenium, copper, and plays a major role in uptake of water. Both the fungus and the plant host does not exist in nature without each other.

In USA, it is found in many areas that were deforested due to suburban land occupancy, therefore loss of habitat in its historic southern distribution, where no new reports were made after 1950 despite considerable mycological survey activity.
Same threats apply in Canada where it grows in the southern hardwood forest under oak, beech and hemlock which are threatened by suburban development and agricultural expansion in the St-Lawrence river valley.

Surveys by mycological clubs to confirm its presence to acheive local protection.

There is a large uncertainty on the number of possible new localities as the northeastern hardwood forest covers a very large territory.  For this reason we had to estimate the number of possible new localities to be 50 times higher than the known ones.

In northeastern North America, where this species is found, there are numerous groups of amateur mycologists. Members of these groups can be recruited and instructed where to find and how to identify this species so they can target this species during forays. Data from amateur mycologists can be critical to define A. ristichii population size, distribution and trends, as well as its ectomycorrhizal associations.

New surveys with the help of local mycological clubs and a campaign for **Species wanted** will be used to refine this estimate of unknown sites.
Collectors will also be asked to be more precise on the potential mycorrhizal host.