Summary:
Features include 1) resupinate growth on wood, 2) a waxy-gelatinous fruitbody that is grayish blue, grayish white, or even pale ochraceous, the surface smooth to uneven, the margin distinct to diffuse, 3) spores that are nearly round to elliptic, with a pronounced suprahilar depression, warted, inamyloid, and colorless, 4) basidia that are short-cylindric and pleural, 5) a monomitic hyphal system, the hyphae with clamp connections.

Microscopic:
SPORES 4-6 x 3.5-5 microns excluding warts, broadly elliptic-dacryoid [elliptic - tear-shaped], verrucose (ornamentation not soluble in KOH), inamyloid, colorless; BASIDIA 4-spored, 10-18 x 6.5-8 microns, cylindric, pleural, without basal clamp connection; HYPHAE monomitic, 1-3.5 microns wide, gelatinized, septa not observed (but according to the literature, septa are present), (Breitenbach), SPORES nearly round to elliptic, "adaxial side concave with a distinct suprahilar depression", warted, when fully developed usually 6-6.5(7) x 4.5(5) microns, inamyloid; BASIDIA short-cylindric, pleural, generally 10-18 x 6-8 microns, with 4 sterigmata and a basal clamp connection; HYPHAE monomitic, some hyphae parallel to substrate, 2-2.5 microns, thin-walled, and rather straight, other hyphae intermingled, conglutinate and strongly gelatinized, often irregularly inflated, all hyphae with clamp connections, (Hjortstam), SPORES 3.5-6 x 3-6 microns; HYPHAE mostly parallel to the substrate, nodose-septate, (1)1.5-2.5 microns wide, "conglutinate or the walls becoming gelatinized", (Liberta)

Notes:
Xenasma tulasnelloideum has been found in BC, OR, NS, ON, FL, GA, IA, IL, IN, MA, MO, NC, NH, NJ, NY, OH, RI, and VT, (Ginns). Distribution includes Denmark, Finland, Norway, and Sweden, (Hjortstam), and Switzerland and Asia (Breitenbach).