Summary:
Features include 1) resupinate growth on conifer wood or on hardwood, 2) a grayish white to yellowish fruitbody, poroid-floccose and reticulate under a hand lens with visible cystidia, the margin indistinct and the subiculum usually sparse, 3) spores that are slightly allantoid, smooth, inamyloid, and colorless, 4) cystidia that are cylindric and thick-walled, often dissolving in KOH, slightly to distinctly amyloid, usually slightly flexuous [wavy], narrowing slightly towards the obtuse apex with the narrow lumen gradually expanded so that the apex is thin-walled, the base bifurcate, and 5) a monomitic hyphal system, the hyphae with clamp connections.

Microscopic:
SPORES (8)9-10(11) x 1.8-2 microns, suballantoid, smooth, thin-walled, "in some specimens slightly flexuose"; BASIDIA 4-spored, 10-15(18) x 4-4.5 microns, subclavate, narrowing toward the base but not distinctly stemmed, (often with a suburniform appearance), in fairly loose clusters, thin-walled, inamyloid, with a basal clamp connection; CYSTIDIA cylindric, "usually with a slightly flexuose appearance", generally up to 100 microns long and with a width of 5 microns in the middle part, "narrowing slightly towards the obtuse apex with the capillary lumen gradually expanded" so that apex is thin-walled, in Melzer''s reagent varying from grayish to a distinct bluish reaction; HYPHAE monomitic, 2-2.5 microns wide, "thin-walled or with slightly wall thickening", "composed of a fairly dense, inamyloid tissue", all hyphae with clamp connections, (Hjortstam), SPORES 7-9 x 1.5-2 microns, cylindric, slightly allantoid, smooth, inamyloid, colorless; BASIDIA 4-spored, 8-15 x 4-6 microns, clavate, with clamp connection; LYOCYSTIDIA 60-130 x 4-6 microns, narrowly cylindric, thick-walled, "lumen gradually enlarging toward the tip, soluble in KOH", amyloid, base rooting; HYPHAE monomitic, 1.5-3.5 microns wide, thin-walled to thick-walled, septa with clamp connections, (Breitenbach), SPORES (6)7-10(11.5) x 1.5-2(2.5) microns, narrow cylindric, "sometimes slightly broadened and somewhat curved just above the base"; BASIDIA 4-spored, (7.5)8.5-14(18.5) x (2.75)3.5-4.5 microns, subclavate, sterigmata about 4.5 microns long, slender, erect; CYSTIDIA (20)50-100(135) microns long, subcylindric, 3.5-5.5(6) microns wide near base, narrowing to (2.5)3-4.5(5.5) microns at apex, smooth, inamyloid to slightly amyloid, walls thick but thinning with a gradual expansion of the capillary lumen to end in an obtuse, thin-walled apex, (1/10)1/8-1/3(1/2) the length of the cystidium, "the thickened walls sensitive to KOH, in some specimens showing a delayed solubility especially in the upper half of the cystidium", the stem in some collections showing a series of constrictions along its length; SUBICULUM composed of hyphae 2-3 microns wide, rigid-walled or sometimes thick-walled, with clamp connections, the "walls swelling more or less, sometimes dissolving in 10% KOH", (Weresub)

Notes:
Tubulicrinis angustus has been found in BC, OR, ON, PQ, MA, RI, and WI, (Ginns). It also occurs in Denmark, Finland, Norway, and Sweden, (Hjortstam), and Switzerland (Breitenbach).

Synonyms and Alternate Names:
Hypoxylon hydnicolum (Schwein.: Fr.) Sacc.
Sphaeria hydnicola Schwein.