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Species Information
Summary: Features include 1) a slightly flattened, short-lived, white, bracket-like fruitbody that is finely tomentose at first, often with a yellowish pellicle, 2) spongy or cheesy texture when fresh, 3) small pores, 4) a fragrant odor when fresh, and 5) microscopic characters including characteristically branched generative hyphae in the context.
Tyromyces chioneus has been found in BC, WA, OR, ID, MB, NB, NF, NS, ON, PQ, SK, AK, CT, FL, IA, IN, KY, MA, MD, ME, MI, MN, MO, MT, NC, NH, NJ, NY, OH, PA, TN, VA, VT, WI, and Europe, (Gilbertson).
Cap: up to 8cm broad and 10cm wide, 0.5-2cm thick, bracket-like, flattened horizontally to slightly convex, "broadly attached to semicircular and dimidiate, more rarely spathulate", "soft and fleshy when fresh, drying rather hard and brittle"; at first whitish, then cream, light yellowish, or pale grayish to straw-colored, when old dirty yellowish to pale sordid gray; not zoned, at first finely tomentose, soon becoming bald, then finely scrupose and warted, a smooth pellicle develops that on drying becomes radially to irregularly wrinkled, (Gilbertson)
Flesh: up to 1.5-2cm thick at base, usually distinctly thicker than tube layer; dense and white when dry, (Gilbertson), "soft and watery at first, drying hard and chalky; white", (Phillips), 0.2-1.5cm thick, soft and spongy or cheesy when fresh, crumbly when old and dry, (Arora)
Pores: 3-4(5) per mm, angular to round, mostly thin-walled; white to pale cream, slightly shiny, drying somewhat darker; tube layer up to 0.8cm thick, colored as pore surface, (Gilbertson)
Odor: weakly to moderately aromatic, sweetly spicy with a citrus tinge, (Ginns), with a slight aromatic scent when fresh, (Gilbertson), fragrant when fresh (Phillips)
Microscopic: spores mostly 4-5 x 1.5-2 microns, cylindric to slightly bent, smooth, inamyloid, colorless, thin-walled; basidia 4-spored, 10-15 x 4-5 microns, clavate, with basal clamp; cystidia absent, fused cystidioles 9-13 x 4-5 microns; hyphae dimitic, "generative hyphae with clamps, in the context intricately branched and twisted and difficult to separate in long sections, sidebranches partly as tube-like hyphae, often separated by a septum, but also with repeated branchings, these hyphae are very characteristic and diagnostic for the species, they are randomly oriented, occasionally mixed with more unbranched, long hyphae, both types with rather numerous clamps, thin- to thick-walled, 3-8 microns wide, in parts collapsed, in the trama more or less parallel and more straight, mostly 2-4 microns wide"; skeletal hyphae present only in trama, 2-4.5 microns wide, straight, thick-walled, (Gilbertson), spores 4-5 x 1.5-2.0 microns, cylindric, some slightly curved, (Ginns)
Spore Deposit: white (Phillips)
Habitat / Range
annual, single or a few specimens together, on dead wood of hardwoods, causing a white rot, (Gilbertson), summer to fall (Buczacki)
Similar Species
Tyromyces galactinus has a cap surface that is white to pale gray, and strigose to hispid, spores are 2.5-3.0 x 2.0-2.5 microns, and skeletal hyphae are lacking, whereas T. chioneus has a cap surface that is white to dark gray, and finely tomentose to bald, spores are 4-5 x 1.5-2.0 microns, and there are skeletal hyphae in the trama, (Ginns(28)). Calcipostia guttulata and Postia stiptica are similar in appearance and microscopically, but those species have a bitter taste, fresh or dried, and they are not restricted to hardwoods. In addition, Postia stiptica has a rough cap that usually has small, back dots on the surface, and C. guttulata has a weakly zonate cap with saucer-shaped depressions 0.1-0.3cm in diameter, an exudation of drops of liquid on most fresh fruitbodies, and a faint greenish cast to the pore surface. (Ginns(28)). Postia tephroleuca has slightly narrower spores (4.5-6 x 1-1.5 microns), a monomitic hyphal system without the characteristic branched generative hyphae, and produces a brown rot, (Gilbertson). Postia tephroleuca may lack its typical mouse-gray cap surface, in which case it is differentiated by its narrower (1.0-1.5 microns), allantoid spores, (Ginns(28)).
