Status suggested is Data Deficient. Lactarius fulignellus is a somewhat cryptic species, so is likely under-reported. Further documentation of its occurence is desired to determine habitat requirements. It may favor oak woodland in wetter conditions.
Microscopic characters must be examined to reliably separate this species from other similar Lactarius mushrooms. The spores are larger and the caulocystidia are wider and more strongly pigmented than in L. fumosus var. fumosus and var. fumosoides. Important macroscopic characters are the reddish staining, the close to subdistant, broad gills (not narrow and crowded), and the mild to mildly bitter taste.
Lactarius fuliginellus is a poorly documented species in North America. It is recorded from Michigan, Minnesota, Illinois, Indiana, and West Virginia in the USA; and Nuevo León and Veracruz in Mexico.
In 1996, Lactarius fuliginellus was listed as a special concern species in Minnesota (at the northwestern limits of its known range).
It is recorded from five states in the USA and two in Mexico. Described from Michigan in 1962 it has been collected 23 times from nine or more locations in Michigan from 1937 to 1987. There are three collections from Minnesota (Anoka County, 1990’s, 2002), four from Illinois (2001, 2009), and two from Indiana (1998, 2004) (Mycoportal and Leacock collection data). There is a tentative identification in West Virginia (2008, Mycoportal). There are records from Mexico: three for Nuevo León (Santiago, 1984, Mycoportal) and reported for Veracruz (Montoya et al. 1990). There were no records on Mushroom Observer.
Population size cannot be estimated well because Lactarius fuliginellus is likely overlooked, being a member of the Lactarius subgenus Plinthogalus. Collections and reports represent about 25 known sites. Total population of mature individuals is roughly estimated at greater than 60,000 (based on 10 genets per site, 5 ramets per genet, and number of sites at least 50 times greater).
Population Trend: Uncertain
Lactarius fuliginellus may prefer hardwood habitats in areas that are near water or that are periodically inundated. The Michigan type collection was from under hardwoods at the edge of a bog. In Mississippi, it was found in bottomland hardwood forest. One of the Minnesota populations, found in two successive years in Anoka County, was located in leaf litter under hardwoods, primarily Quercus spp. and Rubus spp. (blackberry), in a low area that holds water in wet years.
Lactarius fuliginellus is a presumed ectomycorrhizal fungus, one that forms a symbiotic relationship between itself and the roots of oaks and possibly other hardwoods.
In Minnesota, the habitat of lowland hardwoods and the location in Anoka County are vulnerable to disturbance from human activity, including habitat loss and changes in hydrology. Ectomycorrhizal fungi in general are sensitive to nitrogen deposition and other forms of pollution that affect the soil.
There are no current conservation actions. This species can be placed on a watch list to bring it to the attention of mycologists in order to add to its distribution and ecology.
The distribution of L. fuliginellus in North America may be poorly known because this species is easily mistaken for L. fumosus and can only be reliably separated by microscopic characters. Further surveys are needed to accurately document its distribution and abundance, but based on current knowledge its population sizes within the states of Minnesota, Illinois, Indiana, and West Virginia appear to be small. It has been better documented in Michigan. It may be more widespread in Mexico as well.
Hesler, L. R., and A. H. Smith. 1979. North American Species of Lactarius. The University of Michigan Press, Ann Arbor, Michigan. 841 pp.
Smith, A. H., and L. R. Hesler. 1962. Studies on Lactarius - III, the North American species of section Plinthogali. Brittonia 14:432.
David J. McLaughlin
Department of Plant Biology
University of Minnesota
1475 Gortner Ave
Saint Paul, MN 55108