Summary:
Phaeomarasmius erinaceus is recognized by its small size (cap up to 1.5cm), dark brown color, squarrose [rough-scaly] cap and stem and habitat on dead twigs and branches of hardwoods.

Cap:
0.5-1.4cm across, convex, often becoming flat on disc; bay to umber on disc, rust to umber elsewhere, often with ochreous flesh visible in sparsely tomentose areas, "occasionally bleached nearly white on old arctic collections"; "dry, opaque, densely tomentose to fibrillose-scaly", margins fibrillose, (Redhead(26)), 0.5-1.5cm across, "usually convex, sometimes slightly depressed on the disc or disc slightly umbonate"; medium to dark rusty brown, paler and more ochraceous near edge; dry, densely covered with fibrillose scales, the scales erect and nearly spine-like over the disc, toward the margin somewhat appressed, the edge usually fimbriate [fringed] with over-hanging fibrils, (Smith), 0.5-1.5cm across, convex to slightly umbonate; rusty-tawny to dark brick with cinnamon or sienna cinnamon outer part; dry, densely covered in more or less erect fibrillose scales, (Watling)

Flesh:
fleshy-tough, ochreous to dark brick, (Redhead(26)), thin and fairly "tenaceous"; pallid brownish, becoming pallid, (Smith), pallid brown (Watling)

Gills:
adnate, moderately spaced, often becoming broadly ventricose, subgills in 2-3 tiers; buff to fulvous, (Redhead(26)), bluntly adnate, close to subdistant, broad; "whitish becoming pinkish-cinnamon or darker", (Smith), broadly adnate, or adnate-decurrent, subdistant; fulvous or then deep cinnamon, (Watling)

Stem:
0.5-1cm x 0.05-0.15cm, central to slightly off-center, widening downwards, usually curved, stuffed, becoming hollow, tough, often erumpent [appearing to burst through the bark], "arising from a tomentose subcortical subiculum of pale yellowish to cinnamon mycelium"; "bay to chestnut or umber, sometimes with vinaceous tints"; "velvety to sparsely tomentose in minute patches", (Redhead(26)), 0.8-1.5cm x 0.1-0.2(0.25)cm, "equal or base somewhat enlarged, stuffed by a narrow pith, pliant and tough"; pallid brownish in upper part, rusty-red in lower part; lower part densely squarrose-scaly with fine fibrillose squamules [scales], "somewhat silky above the fringe left by the broken veil", (Smith), 0.4-1.5cm x 0.05-0.25cm, equal or slightly enlarged at base, tough; pallid in upper part, colored as cap in lower part: cinnamon or rusty-tawny to date or umber brown; dense erect scales below, with annular fringe of veil fibrils 1/2-1/3 of the way down, (Watling)

Veil:
fringe left on stem by broken veil, (Smith), annular fringe or veil fibrils 1/3 to 1/2 the way down the stem, (Watling)

Odor:
not distinctive (Redhead(26), Smith, Watling)

Taste:
not distinctive (Redhead(26), Watling)

Microscopic spores:
spores 7.2-10.8 x 5.0-6.4 x 5-7.4 microns, oval to obscurely rhomboid in face view, oval to obscurely amygdaliform [almond-shaped] in side view, "slightly compressed, frequently collapsed in revived mounts, smooth, pale reddish brown in KOH", apiculus minute, walls thin to pronounced, paler at apices; basidia 2- or 4-spored, prominently projecting when mature, 26.5-32 x 6.5-9 microns, clavate to obscurely utriform, colorless or rarely pale yellow, "basidioles sometimes fusoid ventricose and cystidia-like"; cheilocystidia "abundant, forming a sterile margin", 26-32 x 6.5-7 microns, "ventricose to fusoid basally, neck elongated, often undulating, mostly irregularly capitate or branched apically or subacute", colorless in upper part, often brownish and some with walls thickened at base, "occasionally with a loose wrinkled membrane over the apex", some cystidia, just below the pileipellis near the cap margin "with distinctly clavate often septate bases", (Redhead(26)), spores 7-10 x 4-5.5 (9-11 x 6-8) microns, "broadly ovate to subrhomboid in face view varying to elliptic", in side view "elliptic to broadly elliptic, some slightly compressed dorsiventrally", apiculus distinct, no germ pore; basidia 1-, 2-, and 4-spored, 18-22 x 7-9 microns, narrowly clavate, colorless to pale ochraceous in KOH and Melzer''s reagent; pleurocystidia scattered, 30-42 x 7-10 microns, fusoid-ventricose with subacute apex, colorless, thin-walled, smooth, in some caps apparently absent, cheilocystidia 20-35 x 4-9 microns, "ventricose at base and with an elongated often crooked and branched neck ending in a subacute to acute apex", neck part with thin, colorless walls "but in basal part the walls often yellowish as revived in KOH"; all tissues inamyloid to weakly dextrinoid; clamp connections regularly present, (Smith), spores 10-14 x 7-9 microns, ovate or pear-shaped to elliptic in face view, no germ pore, smooth, thin-walled, pale honey color in water, slightly more ochraceous in KOH; pleurocystidia absent, cheilocystidia 30-60 x 3-6 microns, apex 1-4 microns, slightly lageniform, or +/- cylindric, sometimes irregular, swollen apex from very acute to obtuse, sometimes irregularly shaped, more rarely branched, colorless, smooth although yellowish at base in alkali solution; clamp connections present, (Watling)

Spore deposit:
amberish-ochreous (Redhead(26)), cinnamon color (Watling), red-brown (Buczacki)

Notes:
It has been found at least in BC, WA, MB, NL, NS, ON, QC, YT, CA, MA, ME, (Redhead(6)).

EDIBILITY

Synonyms and Alternate Names:
Crinipellis alnicola Murrill
Naucoria badia Murrill
Phaeomarasmius aridus (Pers.) Singer
Pholiota erinacea (Fr.) Rea