• Proposed
  • 2Under Assessment
  • 3Preliminary Assessed
  • 4Assessed
  • 5Published

Lactarius paulus P.M. Kirk

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Scientific name
Lactarius paulus
P.M. Kirk
Common names
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
Proposed by
Noah Siegel
Comments etc.
Noah Siegel

Assessment Notes

Taxonomic notes

Described as Arcangeliella parva from a collection made in Sierra County, California, near Sattley (Thiers 1984). These sequestrate Lactarius have been called Arcangeliella; however, it’s a fruitbody form that has evolving multiple times within the genus Lactarius. Thus, this species was transferred to Lactarius (Kirk 2015).

Why suggested for a Global Red List Assessment?

Lactarius paulus is a small sequestrate and hypogeous Lactarius white to pale yellow cap and reduced stipe, a gleba which is completely enclosed, white latex, and acrid taste. Microscopically, it has ellipsoid to ovoid spores, ornamented with a strongly amyloid, complete or broken reticulum.

It is a rare species; currently known from five locations, four around Yuba Pass in the northern Sierra Nevada (California, USA), and one in the central Sierra Nevada, in Stanislaus National Forest.

Geographic range

Only known from five locations in the central and northern Sierra Nevada mountains in California, USA; four of which are in the Yuba Pass area.

Population and Trends

Little is known about the habitat associations of Lactarius paulus. It appears to occur in drier, east-side pine forest. More work is needed to describe the species’ habitat associations and limitations.  Too little is known about habitat and occurrences for a proper assessment of population or trends.

Currently known from five collections, from five locations (Siegel et al. 2019).

Population Trend: Uncertain

Habitat and Ecology

Hypogeous, solitary or scattered, buried under duff and in soil under pines (Pinus spp.) and fir (Abies spp.). Ectomycorrhizal, associated with Pinaceae. Fruiting in spring and early summer. This species is likely dependent on mycophagy (primarily eaten by small mammals) for spore dispersal.


Too little is known about habitat and occurrences for a proper assessment of threats to this species.

Conservation Actions

Research needed

Targeted surveys and revisiting known occurrences, as most collections are historic.

Population size, distribution & trendsPopulation trends

Use and Trade

None known.


Kirk, P.M. 2015. Index Fungorum 278: 1.

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.

Thiers, H.D. 1984. The genus Arcangeliella Cav. in the western United States. Sydowia. 37: 296–308.

Trappe, J.M., R. Molina, D.L. Luoma, E. Cázares, D. Pilz, J.E. Smith, M.A. Castellano, S.L. Miller, & M.J. Trappe. 2009. Diversity, Ecology, and Conservation of Truffle Fungi in Forests of the Pacific Northwest. United States Department of Agriculture. Forest Service. Pacific Northwest Research Station. General Technical Report. PNW-GTR-772.

MyCoPortal. Mycology Collections Portal. Available at: http://mycoportal.org

Country occurrence

Regional Population and Trends

Country Trend Redlisted