Russulales » Peniophoraceae » Entomocorticium

Entomocorticium dendroctoni

Entomocorticium dendroctoni H.S. Whitney 1987, in Whitney et al., Canadian Journal of Botany, 65, 95-102 (1987).

Diagnosis: Basidiocarp primordia at first consisting of an extremely thin, adherent, whitish, byssoid layer and delicate readiating strands, these 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. Scattered clusters of basidia and cystidia develop, arising either directly on the subicular hyphae or elevated on erect hyphae arising from the subiculum, the hymenium spreading, becoming continuous (Figure 1), the initial hymenial layer about 45 -50 µm 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 ca. 500 µm, white to pale cream or buff (Pinkish Buff, Light Buff, or Olive Buff (Ridgway 1912)), the surface smooth, separating readily from the substratum. Hyphae 3-5(-6) µm, the walls thin to slightly thickened, remaining distinct, with a clamp at each septum, branches originating between clamps. Cystidia (Figure 1) 22-60 x 5-10 µm, 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. Basidia (Figure 1) 24-27(-31) X 5.5-6.6 µm, 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. Basidiospores accumulating to form a fragile crust on the hymenium (Figure 2-4), the individual spores mostly ellipsoid and (7 -)8- 10(- 12) x 4-6 µm, frequently narrowed slightly near the middle, rounded distally, tapered slightly proximally to a broad, truncated attachment, occasionally broadly elliptic to subglobose and 8 - 10.5 x 7.5 - 10 µm; wall smooth, thick, appearing multilayered (Figure 8, 9), inamyloid, acyanophilous. Growing in pupal chambers and on the walls of larval galleries of Dendroctonus ponderosae Hopkins on Pinus contorta Dougl. var. latifolia Engelm. Sometimes growing beyond galleries and chambers if separation of bark and wood occurs.

            Index Fungorum Number: IF129958

Figure 1. Drawing of a young fructification of Entomocorticium dendroctoni. (A) Variation in size and shape of mature thick-walled basidiospores, one germinating. (B) Development of basidia and basidiospores. (C) Cystidia. (D) Subhymenial hyphae with abundant clamp connections.

Figures 2-3. Habitat of Entornocorticiurn dendroctoni. Figure 2. Near the start of mountain pine beetle egg galleries (arrows), suggesting a vector relationship with the beetle. ~0.25. Figure 3. In pupal chambers, pupae removed. x0.66.