Summary:
Features include 1) resupinate growth on much decayed wood, 2) a whitish to ochraceous, soft, waxy fruitbody with conic to cylindric spines up to 0.2cm long, each with a tip that is tomentose or brush-like, 3) a fruitbody margin that when immature thins out to a pruinose periphery but when mature is more abrupt, 4) a subiculum that is porose-reticulate, more obvious when immature, 5) spores that are broadly elliptic, smooth, inamyloid, cyanophilic, and colorless, 6) cystidia of 2 types, a) projecting, similar to hyphae, each with a rounded head (normally resinous-encrusted) and enlargements along its length, b) lagenocystidia each consisting of a hypha ending in a needle-like tip that is characteristically encrusted, and 7) a monomitic hyphal system, the hyphae cyanophilic and somewhat thick-walled, with clamp connections.

Microscopic:
SPORES 4.5-6 x 3.5-4 microns, broadly elliptic, smooth, inamyloid, slightly cyanophilic, thin-walled, with 1-2 droplets; BASIDIA 4-spored, at first clavate, then subcylindric with median suburniform constriction, often sinuous, 15-18 x 3.5-5 microns, with basal clamp connection; CYSTIDIA of two types: 1) "capitate, somewhat projecting, little differentiated from sterile hyphal ends", the apical head in the living fruitbody often with a resinous drop (visible under 50x lens), "drying to a brittle cap-like encrustation", the length to first septum 40-75 microns, the head 5-7 microns wide, the encrustation 7-10 microns, beside the apical head also often enlargements along the length of the hyphae, 2) lagenocystidia, appearing like a hypha ending in a needle-like part that is encrusted in its distal part, the apical encrustation about 8-10 microns long, the length to the first septum 30-50 microns; HYPHAE monomitic, about 2-3 microns wide, distinct, cyanophilic, somewhat thick-walled, with clamp connections; sparsely branched and rather straight in the center of the spines, in other parts richly branched and irregularly intertwined, denser and thinner in the subhymenial texture; young hyphae colorless, mature ones yellowish, (Eriksson), SPORES 4.5-5.5 x 3.5-4 microns, oval, smooth, inamyloid, cyanophilic, colorless, with droplets; BASIDIA 4-spored, 12-18 x 3-4 microns, narrowly clavate, with basal clamp connection; CYSTIDIA of 2 types: 1) leptocystidia 35-60 x 3-4 microns, cylindric, with capitate ends that sometimes are surrounded by an amorphous substance, thick-walled, usually with a single septum and clamp connection, and 2) lagenocystidia 25-35 x 2-3.5 microns, "subulate to ventricose, usually with incrusted tips", basal septum with clamp connection; HYPHAE monomitic, 1.5-4 microns wide, cyanophilic, +/- thick-walled, septa with clamp connections, (Breitenbach)

Notes:
Hyphodontia arguta has been found in BC, ID, MB, NB, NS, ON, PE, AZ, CO, GA, IA, IN, MD, MI, MN, MS, NC, NM, NY, PA, and WI, (Ginns), ON, PQ, Austria, Germany, Italy, Spain, Sweden, Tanzania, Iran, Australia, (Langer), Denmark, Finland, and Norway, (Eriksson), and Switzerland (Breitenbach).