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Description type:Original description 
Description:Clavariadelphus occidentalis Methven, sp. nov.
Figs. 8, 12
HOLOTYPUS: TENN: United States, California, Yuba Co., Bullard's Bar Recreation Area, Schoolhouse Campground, 4 Jan 1987, legit A. S. Methven No. 5068 (TENN 47402).
BASIDIOCARP 5-20 cm high, 5-12 mm diam basally, 10-30 mm diam apically, simple, initially subcylindric to subfusiform, enlarged upward in age, then clavate to broadly clavate, finally irregularly, laterally compressed; mycelial hyphae interwoven or aggregated into rhizomorphic strands up to 1 mm diam, white to pallid; base terete, smooth, pruinose, white to pallid where covered, otherwise yellowish white (3A2) to pale yellow (4A3), "ivory yellow," "cartridge buff," "light buff," "pale ochraceousbuff"; hymenium initially smooth, longitudinally rugose to rugulose in age, initially light yellow (4A5-4) to orange white (5A2), "light buff," "pale ochraceous-buff," "pale ochraceous-salmon," "warm buff," "chamois," "light ochraceous-buff," "cream buff," finally light orange (5A4-3) to greyish orange (5B4-3, 6B4-3), "capucine buff," "pale yellow-orange," "cinnamon-buff," "pinkish cinnamon"; apex initially subacute, then obtuse or broadly rounded, smooth, concolorous with the hymenium; surface staining slowly, irregularly brown (6E6-4, 7E6-4) to dark brown (7F6-4), "verona brown," "mikado brown," "russet," "mar's brown" where cut or bruised, staining more conspicuously downward; flesh initially solid, becoming soft and spongy upward as the apex enlarges, white to pallid, an exposure staining slowly, irregularly brown (6E6-4, 7E6-4) to dark brown (7F6-4), "verona brown," "mikado brown," "russet," "mar's brown". ODOR AND TASTE not distinctive.
MACROCHEMICAL REACTIONS: FeC13, FeCl3 + EtOH, ANO, PHN, PYR, PCR, GUA, SYR = positive; KOH, NH40H, NAP, TYR = negative.
MYCELIAL HYPHAE 2.5-4 µm diam, branched, clamped, uninflated; walls thin or irregularly thickened to 1 µm, hyaline in KOH, refractive under phase contrast, smooth, echinate or echinulate; projections up to 1 µm high, hyaline, insoluble in KOH, refractive under phase contrast, acyanophilous; clamps uninflated or inflated (-9.5 µm), sometimes medallion or ampulliform; hyphal contents amorphous, hyaline in KOH. TRAMAL HYPHAE 4-12 µm diam, more or less parallel to longitudinally interwoven basally, more loosely interwoven upward, radially interwoven beneath the subhymenium, uninflated, inflated (-13.5 µm) or broadly undulate, branched, clamped; walls thin or irregularly thickened to 1 µm, hyaline in KOH, refractive under phase contrast, smooth; clamps uninflated or inflated (-16 µm), sometimes medallion or ampulliform; hyphal contents amorphous, hyaline in KOH. GLOEOPLEROUS HYPHAE 2.5-5 µm diam, arising from generative hyphae at clamp connections, scattered throughout the trama, more abundant downward, uninflated, inflated (-8 µm) or strangulated, branched, clamped; walls thin, hyaline in KOH, smooth; clamps uninflated or inflated (-12 µm), sometimes medallion or ampulliform; hyphal contents subopalescent, yellow in KOH, refractive under phase contrast, cyanophilous. SUBHYMENIUM rudimentary; hyphae 2.5-5 µm diam, interwoven, branched, clamped, uninflated; walls thin, hyaline in KOH, smooth; clamps uninflated; hyphal contents amorphous, hyaline in KOH. HYMENIUM thickening, extending from near the base of the basidiocarp over the apex, composed of basidia and leptocystidia: LEPTOCYSTIDIA 55-85 x 2.5-5 µm, scattered among and scarcely projecting beyond the basidia, cylindric, subcylindric or strangulated, inflated apically at maturity, then narrowly clavate, at times apically or subapically branched, clamped; walls thin, hyaline in KOH, smooth; clamps uninflated; hyphal contents amorphous, pale yellow in KOH, acyanophilous: BASIDIA 70-125 x 9.5-14 µm, narrowly clavate to clavate, inflated apically at maturity, then broadly clavate, clamped; walls thin or irregularly thickened, hyaline in KOH, smooth; clamps uninflated; basidial contents multiguttulate and refringent to aguttulate and amorphous, pale yellow in KOH; sterigmata (2) -4, 8-12 µm long, broadest basally, narrowed to an obtuse apex, incurved. BASIDIOSPORES white in deposit, 9.5-13 x 5.5-7 µm (Lm = 11.1 µm; Wm = 6.3 µm; E = 1.4-2.0; Em = 1.7); broadly ovate to amygdaliform; walls thin, hyaline in KOH, smooth; contents multiguttulate and refringent to aguttulate and amorphous, pale yellow in KOH; acyanophilous, inamyloid; hilar appendage oblique with an obtuse apex.
HABIT, HABITAT, AND DISTRIBUTION: Scattered to gregarious, infrequently in caespitose clusters; terrestrial; duff; coniferous or mixed coniferousdeciduous forests: Alaska, Arizona, California, Idaho.
Clavariadelphus occidentalis is one of several taxa in sect. Clavariadelphus passing under the name C. pistillaris sensu lato. Clavariadelphus occidentalis differs from the latter by its light yellow basidiocarps which darken to greyish orange in age, habitat in coniferous or mixed coniferous-deciduous forests, and smaller basidiospores (10.5-14 x 6-7.5 µm for C. pistillaris). Other taxa within sect. Clavariadelphus with which C. occidentalis might be confused include C. subfastigiatus, C. caespitosus, and C. fasciculatus: Clavariadelphus subfastigiatus is distinct from C. occidentalis in its pallid fleshcolor to light cinnamon basidiocarps, forest green staining reaction with KOH, and smaller basidiospores (8-10.5 x 5-6 µm). Clavariadelphus caespitosus differs from C. occidentalis by its slender, narrowly clavate, greyish red to dull red basidiocarps with subacute apices, caespitose growth habit, and smaller basidiospores (8-11 x 4.5-6.5 µm). Clavariadelphus fasciculatus, known at this writing only from Mexico, is unique in its strongly fasciculate growth habit, pinkish orange basidiocarps, larger basidiospores (11-14 x 5-7 µm), and acerose- to acicular-shaped crystals encrusting the walls of the mycelial hyphae.
Small, immature basidiocarps of C. occidentalis might also be confused in the field with C. ligula and C. sachalinensis. These taxa can readily be segregated microscopically, however, by size and shape of basidiospores. Basidiospores of C. occidentalis are broadly ovate to amygdaliform in profile with an Em <2.0, while those ofC. ligula and C. sachalinensis are narrowly ellipsoid to boletoid in profile with an Em> 3.0.
 
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