Hygrophorus nemoreus is a European species, but the variety raphaneus was described by from Riverside County, California, USA (Largent 1985). It needs to be elevated to species rank.
Hygrophorus nemoreus var. raphaneus is a rare mushroom known from southern and central California live oak woodlands.
Currently known from five records from four locations, from a habitat in decline due to droughts, fire and development.
Currently known from three voucher confirmed locations, and a photo record from a fourth location. Two sites are within two miles of each other in the Santa Ana Mountains, and two records are from Santa Cruz county. A single specimen was brought into the Santa Cruz Fungus Fair in 2012, which likely came from Monterey County. Potentially, it could occur in coastal and coast range oak forests from Santa Cruz County, south into Mexico (no records currently exist south of Riverside County), and in the oak zone in the Sierra Nevada foothills.
A collection made in Douglas Co., Oregon, USA, called Hygrophorus nemoreus is likely a different species, and is not included in this assessment.
Currently known from three voucher confirmed locations, and a photo record from a fourth location. Two sites are within two miles of each other in the Santa Ana Mountains, and two records are from Santa Cruz county. A single specimen was brought into the Santa Cruz Fungus Fair in 2012, which likely came from Monterey County.
Habitat is under treat, due to droughts, fire, and urban development, and populations are likely decreasing.
Population Trend: Decreasing
Typically solitary, more rarely scattered in soil or duff under oaks; typically in hot, and often dry oak woodlands of southern California. Ectomycorrhizal, with oaks; (Quercus agrifolia, Q. dumosa). Fruiting in winter and spring.
Habitat loss due to climate change, leading to droughts and prolonged dry spells, which in part lead to stand replacing fires. Urban development in much of southern California.
Add to conservation list to protect this species. Do minimal invasive fuels reduction remediation in known and potential habitat to limit damage from wildfires.
Targeted surveys for this species, and a better understanding of habitat requirements and restraints. Taxonomic work, elevating it species rank.
Largent, D.L. 1985. New taxa of Hygrophorus from California. Mycotaxon. 23:383–404.
Largent, D.L. 1994. The Agaricales (Gilled Fungi) of California 5. Hygrophoraceae. Mad River Press, Eureka, California.
MyCoPortal. 2021. http://mycoportal.org/portal/index.php. Accessed on February 23.
Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. and Ikeda, D. 2019. A Field Guide to the Rare Fungi of California’s National Forests. Bookmobile: Minneapolis, MN. 313 p.