Cleistocybe vernalis

Cleistocybe vernalis Ammirati, A.D. Parker & Matheny 2007, in Ammirati, et al., Mycoscience, 48, 282-289 (2007)

Etymology: vernalis (Latin: occurring in spring).

Diagnosis: Pileus 2.0–6.0 cm in diameter, convex at first with an incurved margin, becoming depressed with decurved margin in age; surface dry, not viscid, appressed fibrillose to squamulose with vinaceous brown fibrils like “kidskin” over a pale pinkish gray ground, becoming slightly more ochraceous brown in extreme age or on drying, at times cracked-areolate and/or margin with scattered patches of submembranous veil remnants; context pale pinkish gray brown, up to 12 mm thick near the stipe apex, tapering to a point at the margin, not changing color where cut, firm, odor strongly farinaceous; cap surface greenish to pale green when KOH applied on fresh material. Lamellae decurrent, close (40–70 reach the stipe), more or less equal number of lamellulae, narrow, up to 10 mm broad near the stipe, pale pinkish gray. Stipe 3.0–6.0 cm long, 7–15 mm wide, equal to slightly tapering downward, concolorous with pileus, surface fibrillose above the annular zone, with coarse irregular patches of veil tissue below, at times several (two to four) basidiomata arising from a common bulbous base; annulus submembranous, superior, pale pinkish gray. Basidiospores (6.3–)7.4–8.4–10.4 × 3.7–4.6–4.8 μm, in face view elliptical to somewhat ovate in outline, in profile view somewhat variable, a few shorter and broad, some reniform, often more elliptical, typically more or less inequilateral and tending to be amygdaliform in outline, apiculus well developed, more or less thin-walled, colorless, empty or with droplets and granules, inamyloid. Basidia 37–44 × 5–6 μm, 4-spored, narrowly clavate, colorless, some with granular materials. Pleurocystidia and cheilocystidia absent. Lamella edges fertile. Lamella trama interwoven to strongly interwoven, more parallel in some areas, somewhat divergent in the compact subhymenium with elements similar to those of Hygrophorus, hyphae mostly 3–12 μm diameter, straight to twisted, walls refractive, thin to somewhat thickened, smooth, only rarely seen with incrustations, colorless to slightly yellowish (walls), no granules, pigments, or oleiferous hyphae seen. Pileipellis interwoven to strongly interwoven, in a few places hyphae more radially arranged (similar in cross section), mostly 3–4.5 μm in diameter, cylindrical, smooth to encrusted, some colorless, often yellowish, not embedded in a gelatinous matrix; pileal trama interwoven to strongly interwoven in cross section, in some places hyphae more radially oriented, cylindrical to broadly cylindrical, at times more enlarged, mostly colorless, wall somewhat thickened, refractive, colorless to yellowish, smooth, rarely encrusted, no oleiferous hyphae seen. Clamp connections present throughout basidiomata. Habit and habitat: Solitary or clustered on soil at edge of dirt road and on sloped road bank, in mixed conifer forests of Abies, Betula, Larix, Pseudotsuga, and Thuja.

Index Fungorum Number: IF531935

Notes:  Cleistocybe vernalis is known from a single locality where it consistently produces basidiomata each spring, and it appears to be a rare species. The pileipellis is not gelatinous, in contrast to C. gomphidioides (see following), and the pileus surface turns green with KOH when fresh. Whether the KOH color reaction is similar for C. gomphidioides is unknown because specimens were not tested with KOH by A.H. Smith. The basidiospores are somewhat smaller, and more consistently elliptical in profile view than in C. gomphidioides, but these features cannot be evaluated from only a single population of C. vernalis. ITS sequences of C. vernalis and C. gomphidioides (including sequences of type collections) differ at 76 nucleotide positions (excluding gaps) among 605 non-gapped sites (648 total aligned sites). The genetic or “p” distance between the two species at the ITS locus is 12.5%. Thus, the vernal occurrence, nongelatinous pileipellis, and ITS data serve to distinguish C. vernalis readily from the otherwise morphologically similar C. gomphidioides. Cleistocybe vernalis was earlier misinterpreted as C. subvelosa by Matheny et al. (2006).