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Page number:154 
Description type:Non-original description 
Description:Clavariadelphus americanus (Corner) Methven, stat. nov.
Figs. 1,3-5
= Clavariadelphus pistillaris var. americanus Corner. 1950. Ann. Bot. Mem. 1: 692.
= Clavaria pistillaris var. americana (Corner) Leathers. 1955. The genus Clavaria Fries in Michigan. Ph.D. dissertation (ined.), University of Michigan, Ann Arbor. 344 pp.
NEOTYPE (des. mihi.): TENN: United States, Massachusetts, Berkshire Co., White Oaks Road, vicinity of Williamstown, 16 Aug 1986, legit A. S. Methven No. 4724 (TENN 47403).
BASIDIOCARP 3-15 cm high, inserted 1-4 cm in the substrate, 3-12 mm diam basally, up to 30 mm diam apically, simple, initially subcylindric to narrowly clavate, enlarged upward in age, then clavate to broadly clavate; mycelial hyphae interwoven or aggregated into rhizomorphic strands up to 1 mm diam, off-white to pallid; base terete, smooth, pruinose, white or pallid where covered, otherwise yellowish white (4A2) to orange white (5A2), "light ochraceousbuff," "pale ochraceous-buff," "pale pinkish buff"; hymenium initially smooth, longitudinally rugose to rugulose in age, initially pale orange (5A3-2) to greyish orange (5B4-3), "light ochraceous-buff," "pale ochraceous-buff," "cartridge buff," "light buff," "pinkish buff," then brownish orange (6C6-4) "cinnamon-rufous " "cinnamon buff," "cinnamon," "orangecinnamon," finally light brown (7D6-4) to brown (7E6-4) "mikado brown " "verona brown," "fawn color," "army brown"; apex obtuse to broadly rounded, smooth, more or less concolorous with the hymenium; surface staining slowly, irregularly brown (6E6-4, 7E6-4) to dark brown (7F6-4), "verona brown," "mikado brown," "mar's brown," "russet" 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 (7F64) "verona brown " "russet " "mar's brown " "mikado brown". ODOR AND TASTE not distinctive.
MACROCHEMICAL REACTIONS: FeCl3, FeCl3 + EtOH, ANO, PYR, PHN, GUA, PCR, SYR = positive; KOH, NH40H, TYR = negative.
MYCELIAL HYPHAE 2.5-5 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 mm high, hyaline, insoluble in KOH, refractive under phase contrast, acyanophilous; clamps uninflated or inflated (-8 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 (-16 µm) or broadly undulate, branched, clamped; walls thin or irregularly thickened to 1 µm diam, 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 (-8 µm), sometimes medallion or ampulliform; hyphal contents amorphous, 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 55-80 x 2.5-5.5 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 60-110 x 8-12.5 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, 7-9.5 µm long, broadest basally, narrowed to an obtuse apex, incurved. BASIDIOSPORES white in deposit, 8-12 x 4.5-6.5 µm (Lm = 9.6 µm; Wm = 5.2 µm; E = 1.6-2.1; Em = 1.8); 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, less commonly in caespitose clusters; terrestrial; duff; mixed coniferous-deciduous forests in association with Quercus and Pinus, eastern North America: Illinois, Maine, Massachusetts, Michigan, Minnesota, New York, North Carolina, Nova Scotia, Ohio, Ontario, Pennsylvania, Tennessee, Vermont, and Wisconsin.
Corner (1950) described C. pistillaris var. americanus from frondose wood in eastern North America. Although Corner (1950) published a Latin diagnosis for var. americanus he did not designate a type specimen having examined no North American specimens at the time.
Instead, Corner based his variety an previous literature reports of C. pistillaris in North America, noting that it differed "in colour, form, and small spores from the European species."
In an attempt to bring order to the taxa similar to C. pistillaris in North America, Wells and Kempton (1968) proposed C. cokeri based an "Coker's excellent notes, the good spore deposit, Miss Eaton's fine illustration (Coker, 1932 [sic], P1. 23)" and Coker's specimen (No. R 27, NCU). Wells and Kempton (1968) did not include Corner's var. americanus in their preliminary study of Clavariadelphus in North America, concluding that var. americanus was "based an literature" and because "we have seen no specimens which could be referred to it." Corner (1970), in a critical rebuttal, noted that Wells and Kempton dismissed "Coker's contribution and discarded the idea of var. americanus because it was based an literature and because they had seen no specimens which could be referred to it." Corner (1970) went an to say that var. americanus was based "not an literature (? belles lettres) but an the scientific researches of Harper, Coker, and Wehmeyer by direct citation and of Burt and Doty by reference in my Table XXI (Monogr. p. 282)." In Corners own words then, his protologue (Corner, 1950) for var. americanus was taken from literature and in no part from specimens he had examined. After examining the collections for which Corner (1950) cited spore measurements in Table XXI, I found them to be representative of several discrete taxa. Coker's specimen from Connecticut (No. R 27, NCU) is the holotype of C. cokeri Wells and Kempton, Wehmeyer's collections (Smith 1417, Wehmeyer 1417x, MICH) are C. americanus, Doty's specimens areC. occidentalis, two of Coker's collections cited from New York (Burnham 68, 71, NCU) are C. americanus and C. truncatus, respectively, and Coker's collections from North Carolina are C. americanus (Nos. 1913, 3793, NCU) and C. unicolor (No 4770, NCU). It is little wonder, then, that Wells and Kempton were confused by Corner's concept of var. americanus.
Following an examination of specimens labeled as C. pistillaris from eastern North America I believe one element of Corner's conglomerate taxon is more accurately recognized as autonomous. In order to provide maximum taxonomic data, one of my collections has been selected as a neotype for this taxon. Although the basidiocarps of C. americanus are similar in coloration to those of C. pistillaris, they are generally not as robust, the flesh has a sweet or nondistinctive taste, the basidiospores are smaller (10.5-14 x 6-7.5 µm for C. pistillaris), and it grows in mixed deciduous-coniferous forests in association with Pinus and Quercus.
In eastern North America, C. americanus is most likely to be confused with C. cokeri and C. flavidus. Clavariadelphus cokeri is distinct in its caespitose to fasciculate growth habit in hemlock forests, pinkish buff to rose pink basidiocarps, which are at times branched apically, and longer, narrower basidiospores (Lm = 10.3 µm; Wm = 4.4 µm). Clavariadelphus flavidus occurs in mixed coniferous-deciduous forests, produces bright yellow to lemon yellow basidiocarps, flesh without a distinctive taste, and the smallest basidiospores in subg. Clavariadelphus (7-10.5 x 4.55.5.um).
In cases where the apex of the basidiocarp has been damaged during development, and becomes more or less truncate or turbinate as a result, C. americanus might be confused with C. unicolor (Rav. apud Berk.) Corner, which is found in similar habitats. Clavariadelphus unicolor is distinct, however, by its violet-brown to lavender-brown basidiocarps which become truncate early in development, often appearing cantharelloid or craterelloid at maturity, and longer, narrower basidiospores (Lm = 10.3 µm; Wm = 5.0 µm). As long as several basidiocarps at different stages of development are available, there is little problem in segregating these two taxa.
 
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