Wetm.
Identity
Unique IDELEMENT_GLOBAL.2.125966
Element CodeNLLEC1C050
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryFungus
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomFungi
PhylumAscomycota
ClassLecanoromycetes
OrderPeltigerales
FamilyNephromataceae
GenusNephroma
Other Common NamesNéphrome cryptique (FR)
Concept ReferenceEsslinger, T.L. and R.S. Egan. 1995. A sixth checklist of the lichen-forming, lichenicolous, and allied fungi of the continental United States and Canada. The Bryologist 98(4): 467-549.
Taxonomic CommentsNephroma occultum is the only North American representative of a group of Nephroma species otherwise endemic to southern South America (McCune and Geiser 1997).
Conservation Status
Rank Method Rank calculation - Biotics v2
Review Date2025-03-05
Change Date2025-03-05
Edition Date2025-03-05
Edition AuthorsDaphne Stone, rev. Johnson, J. (2025)
Threat ImpactHigh
Range Extent200,000-2,500,000 square km (about 80,000-1,000,000 square miles)
Number of Occurrences81 - 300
Rank ReasonsNephroma occultum is a foliose lichen found in humid old-growth forests of the Pacific Northwest, from southern Alaska to western Oregon, United States. Approximately half of the occurrences are found in British Columbia, Canada. Since it is primarily restricted to old-growth forests in very humid intermontane areas at lower elevations, it is very threatened by logging with additional threats from climate change and forest pests.
Range Extent CommentsNephroma occultum is restricted to the Pacific Northwest, from Anchorage, Alaska to southwest Oregon. It occurs in the coastal mountains, Cascade Range, and northern Rocky Mountains (CLH 2025, NatureServe 2025). Range extent was estimated using herbarium specimens and NatureServe Network occurrence data collected between 1994 and 2025 (RARECAT 2024, GBIF 2025, NatureServe 2025, CLH 2025).
Occurrences CommentsBy applying a 1 km separation distance to herbarium specimens and NatureServe Network occurrence data documented between 1994 and 2025, it is estimated that there are 220 occurrences rangewide (RARECAT 2024, GBIF 2025, iNaturalist 2025, NatureServe 2025, CLH 2025).
Threat Impact CommentsLogging of old-growth forests is a major threat to Nephroma occultum (Goward 1994). Calculations in a study area in southwestern Oregon show that cutting with retention of individual trees surrounded by small buffers could result in the eventual loss of Nephroma occultum (Rosso et al. 2000). Examination of satellite imagery shows that in British Columbia, 100 of 119 occurrences, in Oregon 54 of 74 occurrences, and in Washington 6 of 18 occurrences are within or near the edge of a recent clear-cut and may be extirpated since the last observation (RARECAT 2024). Despite plans by the British Columbia provincial government to protect old-growth forests in 2020, more than 11,000 hectares of old-growth forest had been logged by 2023 (Labbe 2023). Clear-cuts may also be more susceptible to wildfire due to decreased water storage capabilities (Labbe 2023).
Climate change may directly impact Nephroma occultum by reducing humidity in the forest canopy through warming and drying trends. Climate change may also impact Nephroma occultum by increasing the severity and extent of hemlock looper infestations and wildfires (COSEWIC 2006).