Epithet = dense, thick or compact. Genus = horn-pore.
Annual effused poroid crust, spreading over wide area; up to 3 mm thick. Brightly colored orange, reddish orange to brownish orange, drying reddish brown. Margin pale and matted mycelioid. Texture cheesy or rubbery, can peel or scrape off the log. Pores very small at 7 to 8 per mm.
Microscopic characters: generative hyphae with clamps, cystidioles absent; spores narrowly allantoid (curved), small, 3.5–4.5 × 1–2 µm.
Most similar pored crusts in the Midwest have different coloration, larger pores, or different spores.
Meruliopsis taxicola is reddish to dark purple with a broad white margin; pores angular, 2 - 4 per mm; clamps absent, spores 4.5–6 × 1–2 µm; typically on conifers.
Ceriporia punicans has pore surface even, white or pale pink in fresh condition, orange to pinkish orange when dry, with vinaceous red stains when bruised; spores are 4–5.5 × 1.5–2 µm.
White rot on dead hardwoods, less common on conifers.
Summer and fall; July to November for Chicago area. Old fruitbodies can be found in the spring, often with margins peeling away from the wood.
North America, Cuba, in French and British Guiana, Ecuador, Canary Islands (Spain), Tahiti, New Zealand, and reported from Japan. Note that old historic collections must be physically verified; two-thirds of the Field Museum collections labeled as such are obviously not this genus.
Chicago Region status
Uncommon. Nine or more collections known for Chicago. The historic collections for Chicago area were misidentified apparently due to incorrect species concepts.
The nearest historic collections identified as P. spissa are from Geneseo, Henry County, in western Illinois, collected by E. T. Harper, August 1915, and then split among several herbaria (BPI, MICH, TENN, UC); but these are likely misidentified. There is a 1954 collection from Lee County. The species Poria spissa is incorrectly described in Moffatt (1909, p. 122, as perennial!), giving three Chicago area locations, but the Field Museum herbarium specimens are a perennial, resupinate Phellinus s.l.
The actual historic collection of C. spissa by E. T. Harper, River Forest, 1908, was misidentified as Poria rufa (= Poria taxicola); this collection was split among several herbaria: Mich, NY, TENN, UC.
The Morton Arboretum herbarium has a collection from their east woods made by Arboretum naturalist Richard Wason in November 1988. We found it recently on a foray in northern Cook County, October 2014. I looked through our unknowns and found one more collection, August 2000, for southern Cook County. Then it was found again in July 2015 in northern Cook County. IMA forays found it in DuPage county in 2017 and several places in 2018.
Taxon Details and Links
Ceriporiaspissa(Schwein. ex Fr.) Rajchenb.,
Mycotaxon 17: 276 (1983)
USA, North Carolina, Juglans trunk (walnut). Lectotype: USA, Massachusetts
Apparently the name by Fries is based on the earlier Schweinitz name since the type specimen was from a Juglans trunk.
This species was also transferred to Mucronoporus (1889), Physisporinus (1942), Meruliopsis (1968), Caloporus (1973), Ceriporia (1985), and Gloeoporus (2006). See links below for other synonyms. See the Rajchenberg link below for a discussion of its resemblance to Meruliopsis taxicola (Caloporus), a merulioid species that has a continuous hymenium over the folds.