Basidioma (Alice Hill, iNat59990981)
Basidioma (Alice Hill, iNat59990981)
Upper surface of reflexed cap (R. A. Cronce, iNat299323765)
Brown bruising basidiocarp (Huafang Su, iNat184739306)
Young basidiocarp (Jonathan Frank, iNat302486591)
Very young developing basidiocarp (Taye Bright, iNat197443219)
Generative hyphae and clamp connections
Basidia
Basidiospores
Dextrinoid basidiospores in Melzer's reagent
Sarcoporia polyspora P. Karst.
Sarcoporia polyspora is an effused-reflexed, poroid crust that produces brown rot on downed conifer logs (and rarely hardwood logs). Macroscopically, it is characterized by a soft, cream-colored hymenophore that bruises reddish brown over a few minutes. Under the microscope, its dextrinoid spores separate it definitively from lookalikes such as Fuscopostia fragilis and Postia ptychogaster. Sarcoporia polyspora is across the Northern Hemisphere from America to Europe and Far East Asia (Vlasák et al. 2015). The similar Sarcoporia longitubulata grows on hardwood logs, is thicker, lacks a cartilaginous layer in the basidiocarp, and has a brown spore print.
Details
Brown-rot on saprotroph on conifer and hardwood logs.
Effused-reflexed, poroid, cream-colored, bruising reddish brown over a few minutes with up to four pores per mm; very moist and soft when fresh, brittle when dry, breaking with the appearance of fiberglass; the context contains a gelatinous layer, which is useful for identification in the field, and is seen as thick darker layering in the dried basidioma; margin fimbriate.
Odor described variously as intensely earthy, sweet, or indistinct. Taste slighlty sour.
Not determined.
White.
Found across the temperate Northern Hemisphere. View all sequenced specimens on iNaturalist.
Microscopy
Hyphal system: Monomitic, all septa with clamps; subhymenial hyphae width (3) 3.2–4 (4.3) µm (n = 10); larger gloeopleurous (gelatinous) hyphae observed, staining darker than other hyphae with phloxine, but individuals difficult to make out. Basidia: Clavate, sometimes appearing constricted, with four sterigmata; length (9) 9.8–16.3 (19) µm, width (3.8) 4.1–5.4 (6.1) µm, x̄ = 13 ✕ 4.7 µm (n = 10). Basidiospores: Cylindrical to narrowly cylindrical, smooth, dextrinoid, weakly to moderately cyanophilic, thin-walled to somewhat thick-walled, filled with lava lamp-like lipid globules that are yellowish green in KOH and phloxine; length (5) 5.2–6.1 (6.6) µm, width (2.4) 2.5–3.1 (3.4) µm, x̄ = 5.7 ✕ 2.8 µm, Q (1.7) 1.8-2.3 (2.5), x̄ = 2.1 (n = 30). Sterile structures: Absent.
Studied Specimens
iNat59990981. 18 September 2020. Angell, Ann Arbor, Washtenaw Co., MI, USA, 42.2792 -83.7220. University of Michigan Fungarium (MICH340650). Sequences: MW718874 (ITS).
References
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Vlasák J, Vlasák Jr. J, Kinnunen J, Spirin V. 2015. Geographic distribution of Sarcoporia polyspora and S. longitubulata sp. nov. Mycotaxon 130:279–287. PDF Link
Citation
Dirks, Alden. 2026. Species profile for Sarcoporia polyspora P. Karst. CrustFungi.Com. https://crustfungi.com/species/sarcoporia-polyspora/. Accessed 2026-01-11.