Summary:
Features include 1) growth in pupal chambers and on the walls of larval galleries of the mountain pine beetle, 2) a fruitbody at first consisting of a thin, white, cottony layer and delicate radiating strands, 3) spores that are mostly elliptic (occasionally broadly elliptic to nearly round), smooth, and inamyloid, 4) basidia that are usually 4-spored, occasionally 1-spored, 2-spored, or 6-spored, 5) cystidia that are thick-walled in the lanceolate to ventricose distal part which becomes encrusted, but thin-walled and sometimes collapsing in the more basal part, 6) hyphae with clamp connections, branches originating between clamp connections. |Mountain pine beetles, which are associated with major damage to lodgepole pine, carry a variety of micro-organisms into host trees at the time of penetration: this basidiomycete grows in the pupal chambers and on the walls of larval galleries (young beetles eat the fungus lining of their pupal chambers), and it is most likely that E. dendroctoni is carried from tree to tree by adult mountain pine beetles, (Whitney), the spores lack an active release mechanism (Ginns).

Microscopic:
SPORES elliptic and (7)8-10(12) x 4-6 microns (mostly), "frequently narrowed slightly near the middle, rounded distally, tapered slightly proximally to a broad, truncated attachment", occasionally broadly elliptic to nearly round and 8-10.5 x 7.5-10 microns, smooth, inamyloid, acyanophilic, wall thick and appearing multilayered, spores "accumulating to form a fragile crust on the hymenium"; BASIDIA 24-27(31) x 5.5-6.6 microns, "clavate or suburniform, often irregular, frequently secondarily septate, collapsing after spore production (often while the spores are still attached), mostly 4-spored, a few with 1, 2, or 6 spores, these born symmetrically on short, broad sterigmata"; CYSTIDIA 22-60 x 5-10 microns, "smooth, thick-walled above, mostly becoming incrusted, thin-walled and sometimes collapsing below the incrustation, incrusted portion lanceolate to ventricose or irregular, often sharply bent basally, especially in those formed initially"; HYPHAE 3-5(6) microns wide, walls thin to slightly thickened, remaining distinct, with a clamp connection at each septum, branches originating between clamp connections; HYMENIUM begins with scattered clusters of basidia and cystidia, "arising either directly on the subicular hyphae or elevated on erect hyphae arising from the subiculum, the hymenium spreading, becoming continuous", the initial hymenial layer about 45-50 microns thick, "with abundant cystidia, the extremely thin underlying parallel layer of hyphae inconspicuous except at margins and in the initial stages of basidiocarp development, the hymenium thickening, the basidiocarp eventually layered and successive hymenia with few or no cystidia", the total thickness eventually up to about 500 microns; the RADIATING STRANDS "mostly composed of less than 10 closely adherent, clamped hyphae that branch infrequently, the branches recurving and adherent, single large crystalline deposits at frequent intervals on the strands"

Notes:
Entomocorticium dendroctoni has been found in BC and MT (Ginns).