Summary:
Also listed in Polypores category. Trechispora mollusca differs from other resupinate white pore surfaces in its cottony-delicate consistency and spiny spores. It differs from crust fungi in general in its distinct pore-like surface. Features include 1) resupinate growth on wood, 2) a soft, fragile, white fruitbody, the pores sometimes splitting to become almost hydnoid, the margin cobwebby to fringed or rhizomorphic, 3) spores that are oval to nearly round, finely spiny, inamyloid, and colorless, and 4) hyphae that are monomitic, the septa with or without clamp connections, often inflated at the clamp connections or septa.

Microscopic:
SPORES 3.5-4.5 x 2.5-3.5 microns, oval to nearly round, echinulate [with slender sharp spines], inamyloid, colorless; BASIDIA 4-spored, up to 14 microns long, 4.5-5.5 microns wide, short-cylindric, with basal clamp connection; CYSTIDIA none; HYPHAE monomitic, hyphae of subiculum 2.5-5 microns wide, colorless, thin-walled, "often ampullate and incrusted, frequently branched, with clamp connections", (Gilbertson), SPORES 4-5.5 x 3.5-4.5 microns including warts, broadly elliptic to elliptic, verrucose; BASIDIA 4-spored, 10-15 x 5-6 microns, short-cylindric often with slight median constriction, with basal clamp connection; HYPHAE monomitic, "in the subhymenium and in the dissepiments straight, thin-walled to slightly thick-walled 2-5 microns wide, encrusted, forming byssoid mats and cordons in the subiculum, septa in the cordons often ampulliform, hyphae in the byssoid mats often with large, globose vesicles 20-25(40) microns, subhymenium lacking or composed of a few layers of richly branched, very short-celled, nearly isodiametric or irregular hyphae but often basidia are born directly on the dissepiment hyphae", (Hjortstam), SPORES 2.5-4 x 2.5-3 microns (not including spines), oval to nearly round, echinulate, inamyloid, colorless, thin-walled; BASIDIA 4-spored, 8.5-16.5(18) x 4-6 microns, subcylindric to clavate; CYSTIDIA absent; HYPHAE monomitic 2-4 microns, colorless, thin-walled, frequently encrusted with irregularly shaped crystalline material, septate with or without clamp connections, frequently with ampulliform swellings at the clamp connection or septum up to 8 microns wide; hyphae of trama similar, (Liberta), SPORES 4-5 x 3-4 microns, broadly elliptic, (Breitenbach)

Notes:
Trechispora mollusca has been found in BC, WA, OR, ID, MB, NB, NF, NS, ON, PE, AK, AZ, CA, CO, LA, MA, MO, MT, NC, NM, NY, PA, SC, TN, and VA, (Gilbertson), also NT, PQ, and MN, (Ginns), and MI, Czechoslovakia, Denmark, Estonia, Finland, France, Poland, Russia, Sweden, Australia, New Zealand, and the United Kingdom, (Liberta). It is common in the whole of Scandinavia (Hjortstam).

Synonyms and Alternate Names:
Hydnum calvatum K.A. Harrison