• Proposed
  • Under Assessment
  • Preliminary Assessed
  • Assessed
  • DDPublished

Amanita zayantensis nom. prov.

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Scientific name
Amanita zayantensis
nom. prov.
Common names
Sandhill Amanita
IUCN Specialist Group
Mushroom, Bracket and Puffball
Assessment status
IUCN Red List Category
Proposed by
Christian Schwarz
Christian Schwarz
Comments etc.
Anders Dahlberg

Assessment Notes



Taxonomic notes

Although currently undescribed (UCSC-F-0079 proposed as the type specimens), this taxon has been known to local mycologists for at least 40 years, but went under the application of the European name A. baccata. In combination with the very distinctive habitat, the elongate/low Q value spores (unusual for an Amanita, see sporograph images), this taxon is distinctive and recognizable, among the few Lepidella in California.

However, although strongly expected that this species is a distinct taxon, publication will require resolution of the use of the name A. baccata in North America. That name has been used indiscriminately to refer to any Lepidella growing in sand. Publication will require inspection of various other collections, including a number of 1935 collections made by Burlingham in Pacific Grove (under Monterey Pine in sandy soil, all made within the span of a few weeks); as well as a number of Idaho and Michigan collections.

Why suggested for a Global Red List Assessment?


This species is a conspicuous agaric, apparently restricted to an extremely rare habitat (the Zayante Sandhills) endemic to Santa Cruz County, California. Less than 4,000 acres of this soil type remain, and of this total, only a small fraction (~ 240 acres) is of the sand parkland that this is suitable habitat for Amanita zayantensis nom. prov.; the entire extent of its global distribution is tiny.

The inherent rarity of the substrate upon which this species specializes, in combination with ongoing threats posed by degradation of its habitat by human foot traffic, invasive plant species, and commercial mining make it a high-priority candidate for assessment and protection.

Geographic range

Only known from Santa Cruz County, California, USA. Occurrence limited to a few areas within Zayante-series soil substrates, which are derived from the degradation of Santa Margarita sandstone (uplifted marine sediments). These sandhill habitats are extremely limited in geographic area, naturally highly fragmented, and are entirely confined to Santa Cruz County. This habitat is home to a number of endemic plants and animals, some of which are federally listed as Endangered species. Entire area of occupancy likely < 240 acres.

Population and Trends

Population size uncertain, but known from fewer than 10 sites, with little room for extrapolation in estimates due to the extreme scarcity of suitable habitat.

Trends: Population likely deteriorating due to increasing impact of invasive species and and degradation of habitat by human activities (both recreational and commercial).

Population Trend: Uncertain

Habitat and Ecology

Ectomycorrhizal; obligate mutualist with either Quercus agrifolia and/or Pinus ponderosa (research needed), but only where these trees are found only on Zayante-series sand soils in Santa Cruz County; especially the small fraction of the sandhills classified as “Sand Parkland”. These soils drain very quickly, and fruiting thus occurs in limited windows of one to two weeks, usually in winter, with records from November through early March depending on rainfall patterns. Peak fruiting often in December. Usually as scattered single fruitbodies, but sometimes in groups of up 8 or so in a small area.

Temperate Forest


Restricted to naturally rare soil substrates that are very vulnerable to degradation by increased foot traffic, unauthorized mountain bike trail construction and off-road vehicle use, habitat change (increase of weedy native trees/bushes displacing Ponderosa Pine and oak), invasion of exotic species (especially Genista and Cytisus spp which prevent recruitment of oak and pine in the understory), climate change directly and indirectly (increased fire risk selects against Ponderosa Pine in favor of Knobcone pines and other floristic assemblages). Much of sandhills subject to resource extraction (sand mining), which is particularly intensive in this area due to low acidity and high aluminum content of Zayante sand.

Mining & quarryingRecreational activitiesIncrease in fire frequency/intensityInvasive non-native/alien species/diseasesHabitat shifting & alteration

Conservation Actions

Remove Scotch Broom from prime areas of critical habitat. [2.2]
Work with land managers of public and private lands to conserve extant populations and habitat. [1.1, 4.3]

Site/area protectionInvasive/problematic species controlAwareness & communications

Research needed

Targeted surveys paired with lab work, focused on micromorphological criteria as well as comparison of sequences obtained using tailored sequencing methodology to determine actual geographic extent of this taxon. Although expected that this provisional taxon is extremely limited in geographic extent, the macromorphological similarity of Lepidella is confounding. The obscuring effect of the use of European names for sand-dwelling Amanita in North America will need to be undone before this species can be published.

Determine host association - if associated with Ponderosa Pine at this locality, much more threatened due to lower rate of recruitment of host compared to oak.

Life history & ecology

Use and Trade


McGraw, J. (n.d.). Santa Cruz Sandhills Habitat Loss. Retrieved April 25, 2016, from http://www.santacruzsandhills.com/habitat_loss.html

Arora, D. (1986). Mushrooms demystified: A comprehensive guide to the fleshy fungi. Berkeley: Ten Speed Press.

Tulloss, Rodham. ” Amanita Baccata Sensu Arora.” Amanita Baccata Sensu Arora. Amanitaceae. Web. 25 Apr. 2016.

Country occurrence

Regional Population and Trends

Country Trend Redlisted