Currently Hydnotryopsis setchellii is know from 11 locations; many of which are quite disjunct. These include historic collections from the Bay Area of California, USA; but no collections have come from this area in over a hundred years. It is reported to occur scattered throughout the Sierra Nevada mountains plus from three collections from the Siskiyou Mountains in southern Oregon. There is a single collection reported from Utah that needs to be reexamined, it is not considered in this assessment. This species appears to be rare but widespread in lower elevation oak woodlands and higher elevation conifer forests which both are under threat.  While it is not possible to rigorously estimate population size, even multiplying the known number of specimens (minus those collected in the late 1800s) 500-1000 times results in a conservative population size of between 4,000-8,000 distributed in several small disjunct subpopulations.  The species is precautionarily assessed as Endangered.

Hydnotryopsis setchellii was described from a collection with no specific details for location beyond “California” (Gilkey 1916).

Choiromyces setchellii (Gilkey) Gilkey and Choiromyces ellipsosporus Gilkey (as Choeromyces ellipsosporus) are synonyms.

Hydnotryopsis setchellii is a rare and poorly known species, with most known populations in the Sierra Nevada of California, with historic collections from the San Francisco Bay Area; also reported from southern Oregon.

There is a single collection reported from Utah (Mycoportal 2021), this highly disjunct collection needs reexamination before being considered in this assessment.

Currently Hydnotryopsis setchellii is know from 11 locations; many of which are quite disjunct. They include historic collections from the Bay Area of California, USA; but no collections have come from this area in over a hundred years. It is reported to occur scattered throughout the Sierra Nevada mountains plus three collections from the Siskiyou Mountains in southern Oregon. There is a single collection reported from Utah (GBIF 2024); this highly disjunct collection should be reexamination and is not being considered in this assessment.

The species is currently known from 11 widespread locations in western USA. Three of the eight California collections are historic, (late 1800’s/early 1900’s) (Mycoportal 2020), and despite efforts to recollect it from the Guadeloupe Mines area (one of the historic sites), it has not been found (Siegel et al. 2019). Three more recent collections come from southern Oregon, in the Medford-Ashland area in oak woodlands.
This species appears to be rare, but widespread in both lower elevation oak woodlands, and higher elevation conifer forests which both are under threat.  While it is not possible to rigorously estimate population size, even multiplying the number of known specimens (minus those collected in the late 1800s) 500-1000 times results in a conservative population size of between 4,000-8,000 distributed in several small disjunct subpopulatons.

Hypogeous, solitary or scattered, buried in duff or soil. Most likely ectomycorrhizal. Collections come from a number of different habitats, and most have oaks (Quercus garryana, Q. kelloggii and Q. agrifolia) as the dominant tree species, a few have Douglas-fir (Pseudotsuga menziesii) and Madrone (Arbutus menziesii) mixed in with the oaks. Many of the Sierra Nevada sites are mixed conifer forests dominated by White fir (Abies concolor). The Utah collection came from an Engelmann Spruce (Picea engelmannii) forest. Fruiting in spring and summer. This species is dependent on mycophagy (primarily eaten by small mammals) for spore dispersal.   

Loss of habitat due to development and urban sprawl in the Sierra Nevada foothills and Silicon Valley. Prolonged droughts and decades of fire suppression have drastically altered western montane forests, leading to thicker, denser, Abies dominated forests. As a result, hotter, stand replacing fires (rather than patchwork and understory burns) are commonplace, altering appropriate habitat drastically, and making it ill-suited for this species.

No specific conservation actions has been identified with regards to this species at this time.

Targeted surveys for this species, especially in the Sierra Nevada, are needed to assess if it is rare or under reported.

None known.

Gilkey, H.M. 1916. A revision of the Tuberales of California. University of California Publications in Botany 6: 275–356

MyCoPortal. 2021. http://mycoportal.org/portal/index.php. Accessed on February 03.

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.