On the type of Coprinus alnivorus Van De Bogart
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Original description
Coprinus alnivorus Van De Bogart in Mycotaxon 4: 241. 1976 (The genus Coprinus in Western North America, part 1: sect. Coprinus).
Holotype: North America: state Washington, Lewis, Cispus Center, Gufford Pinchot Nat. Forest, 25 Oct. 1975, F. Van De Bogart 3370 (WTU).
Pileus at first short-glandiform, then campanulate, then margin becoming laciniate and somewhat revolute, when unexpanded 2.0 cm in length, expanding to 2.0 cm in width. At first white except pale brown at the apex, then becoming grey, then black, but only brownish grey at the apex. Surface at first with a thin arachnoid univeral veil with some minute squamules, in maturity the arachnoid veil largely vanishing but the minute squamules persisting although scattered, surface eventually slightly plicate-striate. Pileal margin at first connected to the stipe with a prominent, scaly white annulus. Flesh thin and fragile. Stipe slender, tapering only slightly from base towards apex, 9.0 cm x 4.0-6.0 mm, hollow, lumen with some loosely interwoven hyphal webbing, surface smooth, glabrous, white. Flesh slightly fibrous, but very fragile. Loose membranous annulus present, 1.0 mm in width, white, very friable and soon disintegrating into small fragments. Lamellae lanceolate, free, very crowded, at first white, then black. Autolysis complete. Odor faint odor of mushrooms.
Spores subglobose to short ellipsoidal, 7.5-10.7 x 6.2-7.5 µm, apiculus small, often not visible, germ pore apical 1.5 µm in diameter. Color soot black en masse and at first dark purple or brownish purple microscopically, then soon black and opaque in 3% KOH. Wall smooth. Basidia trimorphic, short clavate and 16.5-17.5 x 8.0-10.5 µm, clavate and 18.0-26.0 x 8.0-9.0 µm, long pedicellate-clavate and 27.0-29.0 x 8.0-9.0 µm, all four-spored. Cheilocystidia clavate to ellipsoidal-fusiform, apices obtuse to subacute, 28.0-135.0 x 11.0-35.0 µm; hyaline, thin walled, smooth. Pleurocystidia ellipsoidal to subfusiform, apices obtuse to slightly branching, 145.0-182.0 x 30.0-45.0 µm, hyaline, thin walled, smooth. No other cystidia present. Pileal surface a cutis of slender, cylindrical, radially oriented, hyaline, thin walled hyphae. Universal veil of small scales and a thin arachnoid web on pileal surface and base of stipe, scales ar web consisting of slender, non swollen, thin walled, hyaline, cylindrical, septate and clamped hyphae, very interwoven, some branching, most cells separating readily at the septations, 2.5-10.0 µm in diameter, some scales with membranous surface. Clamp-connections present on the hyphae of stipe base, in the universal veil, and in the lamellar trama.
Habitat. Lignicolous, on hard scarcely rotted wood of Alnus sp. in a hardwood rain forest.
This species is similar in many features to C. arachnoideus and likewise appears to be transitional to section Lanatuli in its veil characteristics and possession of pleurocystidia. It differs from C. arachnoideus in most of its microscopical features.
Observations
Spores [20,1,1] 8.0-9.6 x 5.4-7.3 µm, ovoid with slightly conical base and rounded to somewhat truncate apex, and almost central, hardly visible, 1.3-1.5 µm wide germ pore, dark red-brown; Q = 1.25-1.50, av. Q = 1.35; av. L = 8.8, av. B = 6.5 µm. Basidia 16-38 x 8-10 µm, 4-spored, surrounded by (5-)6-7(-8) pseudoparaphyses. Pleurocystidia 90-125 x 27-40 µm, subutriform, narrowly ovoid or subcylindric. Cheilocystidia 80-120 x 28-38 µm, narrowly ovoid, (sub)utriform, oblong or subcylindric. Pileipellis hyphoid. Veil made up of hyphoid, cylindrical, thin-walled elements, up to 150 x 3-8 µm, rather sparse branched and diverticulate. Clamp-connections present.
Notes: The collection of Coprinus alnivorus exists of only one basidiocarp, available in parts, but in good condition. The large cystidia noted by Van De Bogart we did not found in the material.
Coprinus alnivorus belongs to subsect. Alachuani on account of the branched and diverticulate veil. No European species known in that subsection agree Coprinus alnivorus (see: Uljé & Noordeloos, 1997).
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