Harmajaea harperi (Murrill) Dima & P. Alvarado, in Alvarado et al., Fungal Diversity. 90:109-133 (2018)
Pileus 5–11 cm, slightly depressed and presenting a central umbo with age, margin enrolled, smooth or minutely scaly, dry, whitish or grayish in color, brown or pale brown at the center. Lamellae shortly decurrent, crowded, thin, pale brown or gray to whitish. Stipe 4.5–8 x 1.3–2.2 cm, solid, cylindrical, concolorous with the pileus. Context whitish to brownish.
Basidiospores (4.5–) 5.0–6.0 (–7.0) x (2.5–) 3.0–3.7 µm (on average 5.3 x 3.5 µm), Q = 1.40–1.65 (Qm = 1.53), Vm = 34 µm3, ellipsoid in front view, somewhat obovoid or amygdaliform in side view, smooth, spore wall slightly amyloid after a few minutes, not cyanophilous, not collapsing and not adhering in tetrads. Basidia 15–23 x 3.8–5.8 µm, 4-spored, cylindro-clavate, with sterigmata 4 µm long, without carminophilic/siderophilous granulation, apical portion slightly amyloid. Cheilocystidia 26 x 8 µm, cylindrical, scattered, with apical protrusions like ‘‘stag’s antlers’’. Pleurocystidia absent. Subhymenium ramose, arbuscular, 15 µm thick, hyphae shortly branched 3.0–3.5 µm wide. Hymenophoral trama regular, made of broad cylindrical to inflate hyphae 5–16 µm wide, and of thromboplerous hyphae 5–7 µm wide, with yellow content, especially frequent towards in the otherwise hardly differentiated hymenopodium, as well as towards edge. Pileipellis a dry trichocutis of radially arranged, inflate hyphae 5–12 µm wide, with intracellular yellow pigment forming minute granulations, mixed with slender hyphae 2.5–3.0 µm wide, scattered, narrowed at septa, with incrusted wall. Subpellis thick, characterized by an abundance of thromboplerous hyphae with yellowish content in Melzer’s reagent, mixed with regular cylindrical thin walled hyphae 3–8 µm wide. Pileitrama homomorphous, made of mostly parallel hyphae 4.0–6.5 µm wide, with walls 0.3–0.8 µm thick, smooth, mixed with thrombopleurous hyphae 5–9 µm wide, branching and anastomosing, with homogeneous yellowish content, especially abundant towards subpellis. Stipitipellis a caulohymenium. Clamp connections absent, even at the base of basidia and mycelium.
Habitat: widespread in North America (western USA to eastern Canada) and Northern Europe. Under conifers such as Pseudotsuga, Pinus sylvestris and Picea abies.
Index Fungorum number: IF823307
Notes: This species can be easily differentiated because of its habit, ecology and clampless hyphae. Weakly amyloid spores were observed on the collections studied as well as TENN 061314 (USA, North Carolina, Sánchez-García pers. comm.), while spores of C. harperi are usually described as inamyloid, even by such reliable observers as Harmaja (1979) or Bigelow (1982). This could suggest that this feature varies within the same taxon, depending on age, environment, strain, or most probably, on the specific protocol employed. Clitocybe griseifolia Murrill was proposed in the same work as C. harperi (Murrill 1913) from Seattle (USA), and was separated from C. harperi because of its broad lamellae, white stipe, and fragrant odor different from the crowded lamellae, concolorous stipe, and odorless basidiome of C. harperi (Bigelow 1965, 1982). However, some authors (Harmaja 1979) considered C. griseifolia a synonym of C. harperi because of their very similar macro- and microscopical features, as well as identical chemical reactions of the types to Melzer’s reagent (inamyloid), cotton blue (cyanophobic, but weakly cyanophilic in spore and basidia walls) and acetocarmine (carminophobic spore and basidia walls, carminophilic spore nuclei) (Harmaja 1979). This collections of C. harperi have medium-distanced lamellae,a concolorous stipe, and odorless basidiomes, so they do not match C. griseifolia. A single report from France of H. harperi by Bon (1997), corresponding to coll. 741006 in herb. Bon (LIP), was checked under the microscope and revealed clamps in hymenophoral tissues, so it is here reinterpreted as C. alexandri. Finally, some confusion might have existed because of the name Lepista harperi (Murrill) Singer, originally described by Murrill (1913) as Melanoleuca harperi, and later combined to Lepista by Singer (1951) on account of its verrucose spores. When Bigelow (1982) subsumed Lepista within Clitocybe, he noticed the existence of Clitocybe harperi Murrill, and renamed the first species as Clitocybe brunneocephala H.E. Bigelow.