Chaetothiersia vernalis is a rare cup fungus known from 8 voucher confirmed locations, and a few additional photograph records, from the central Sierra Nevada in California, north into the Cascade Range in southern Oregon. It has also been reported from coast range forest in Santa Cruz County, CA. With less than 10 confirmed records, information on the status and trend of this species is limited. However, increased fire frequency and intensity along with a reduction in persistent snow banks throughout its range likely is negatively impacting its population size. Even assuming up to 1000 times the number of known specimens results in an estimated population size of only 10,000 mature individuals distributed in relatively small disjunct supopulations.  It is precautionarily assessed as Vulnerable.

Described from collections made in the Sierra Nevada of California, USA. (Perry & Pfister 2008)

A rare cup fungus known from montane forest in the southern Cascades and Sierra Nevada in California and Oregon, USA. Currently known from ~10 locations.

Chaetothiersia vernalis is currently only known from 8 voucher confirmed locations, and a few additional photograph records in high elevation forest from the central Sierra Nevada in California, north into the Cascade Range in southern Oregon. It has also been reported from coast range forest in Santa Cruz County, CA.

The species is known from the southern Sierra Nevada into southern Oregon, and a purported location from the California Coast Range. Being relatively recently described (Perry & Pfister 2008) with less than 10 confirmed records, information on the status and trend of this species is limited. However, increased fire frequency and intensity along with a reduction in persistent snow banks throughout its range likely is negatively impacting its population size. Even assuming up to 1000 times the number of known specimens results in an estimated population size of only 10,000 mature individuals distributed in relatively small disjunct supopulations.

The species can be found fruiting in spring soon after snowmelt scattered or clustered on decaying logs, stumps, bark and woody debris in soil, typically in Red Fir (Abies magnifica) forests.

Prolonged droughts and decades of fire suppression have drastically altered the high Sierra Nevada forests, leading to thicker, denser Abies dominated forest. As a result, hotter, stand replacing fires (rather than patchwork and understory burns) are commonplace, altering appropriate habitat drastically, and in particular, consuming much large woody debris, likely resulting in habitat ill-suited for this species (Steel et al., 2023).
Although this species hasn’t been shown to require thick winter snowpacks, it appears to benefit from them as it fruits in the spring and summer as the snow melts and recedes. As the climate changes; warmer and drier winters have increased the average elevation of snowpack, and lessened the average depth of the snowpack (Mote et al., 2018). Likewise, hotter temperatures can melt the snowpack more rapidly in spring and summer, shortening the fruiting window.

Little is known of the life history of this species or of its habitat requirements; until they are identified, conservation actions are unknown.

A poorly known species; habitats requirements need to be identified and a better understanding of ecology is needed. Research into the species’ requirement of a dense winter snowpack for fruiting, and if so, is declining snow fall detrimental. Targeted surveys should be made in suitable habitat to better document the species population trends.

None known.

Desjardin, D.E., Wood, M.G. & Stevens, F.A. (2015). California Mushrooms: The Comprehensive Identification Guide. Timber Press: Portland, OR. 560 p.

Mote, P.W., Li, S., Lettenmaier, D.P. et al. 2018. Dramatic declines in snowpack in the western US. npj climate and atmospheric science 1, 2 (2018). https://doi.org/10.1038/s41612-018-0012-1

Perry, B.A. & Pfister, D.H. (2008). Chaetothiersia vernalis, a new genus and species of Pyronemataceae (Ascomycota, Pezizales) from California. Fungal Diversity 28: 65-72.

Siegel, N., Vellinga, E.C., Schwarz, C., Castellano, M.A. & Ikeda, D. (2019). A Field Guide to the Rare Fungi of California’s National Forests. Bookmobile: Minneapolis, MN. 313 p.

Steel, Zachary L., Gavin M. Jones, Brandon M. Collins, Rebecca Green, Alexander Koltunov, Kathryn L. Purcell, Sarah C. Sawyer, et al. 2023. “ Mega-Disturbances Cause Rapid Decline of Mature Conifer Forest Habitat in California.” Ecological Applications 33(2): e2763. https://doi.org/10.1002/eap.2763