Four new species of Albomagister (Agaricales) from eastern North America Author Matheny, P. Brandon Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996 - 1610, USA; Author Lebeuf, Renée Saint-Casimir, QC, G 0 A 3 L 0, Canada; Author Sánchez-García, Marisol Department of Forest Mycology and Plant Pathology, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden; Author Graddy, Mary G. Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37996 - 1610, USA; Author Trudell, Steven A. Herbarium, Burke Museum, University of Washington, Seattle, WA 91895 - 5325, USA; Author Wood, Michal G. , and Else C. Vellinga & 14856 Saturn Drive, San Leandro, CA 94578 - 1349, USA; Author Vellinga, Else C. UC Herbarium, University of California at Berkeley, Berkeley, CA 94720 - 2465, USA text Botany 2024 2024-09-01 102 9 355 365 https://doi.org/10.1139/cjb-2024-0058 journal article 310886 10.1139/cjb-2024-0058 89735046-c669-4e4d-a02a-f527e690b996 add_ISSN_here 15809477 Albomagister griseosquamosus Lebeuf, Matheny & Vellinga , sp. nov. ( Figs. 2A–2F , 3A , 6A–6C ) MYCOBANK: MB851399. Fig. 2. Basidiomes of Albomagister griseosquamosus . ( A and B ) ECV4038 (holotype, TENN-F-064609). ( C and D ) ECV5690 (TENN-F-068763). ( E and F ) HRL3282 (DAOM 984972). Bars = 1 cm. Photos (A–D) by M.G. Wood; photos E–F by R. Lebeuf. Fig. 3. Basidiomes of Albomagister . (A) Albomagister griseosquamosus HRL 4268 (R.L. pers. fung.). (B) Albomagister leucoloma ECV 4202 (holotype, TENN-F-065323). Bars = 1 cm. Photo (A) by R. Lebeuf; photo (B) by E.C. Vellinga. TYPE : USA , Tennessee , Sevier County , Great Smoky Mountains National Park, Elmont, Jakes Creek Trail ( 35.6764 -83.3971 ), in humus in acidic cove hardwood forest under various hardwoods and Tsuga canadensis , 4 August 2009 , J. Lennie ECV4038 ( holotype designated here, TENN-F-064609 ) . DIAGNOSIS: Differs from the white species of Albomagister by the gray squarrose to appressed-scaly pileus and stipe. Habit tricholomatoid. Pileus 25–50 mm wide, campanulate to plano-convex and at times with a low broad umbo, more flattened with age; margin decurved, occasionally torn or undulating; surface dry, initially with a whitish ground color, becoming gray and completely covered with dense small dark gray to blackish squamules, these squarrulose when young and more like fibrillose-scales in more-or-less concentric bands in age, not hygrophanous; context pale gray with dark gray areas, odor, and taste indistinct, absent, or mild. Lamellae sinuate to adnate, close to crowded with ca. 55–60 L and 1–3 tiers of lamellulae, thick, narrow ( 3–5 mm ), white to pale gray or gray with white edges that darken to gray, edges sometimes eroded. Stipe 35–70 × 4–7 mm , equal to slightly narrowed or slightly enlarged at the base; surface dry, veil absent, fibrillose at the apex but mostly with gray scaber-like squamules or with the squamules covering the entire length on a whitish or paler background, squamules smaller towards the base, becoming lacerate-scaly with age; context pale gray, becoming paler towards the nearly white base; hollow. Basidiospores 6– 7.1 –8 × (4)4.5– 5.6 –6.7 µm, Q 1.10– 1.28 –1.57 ( n = 65/4), smooth, elliptic to broadly so or subglobose, with a guttule, hyaline, inamyloid, with a distinct apiculus, white in deposit. Basidia 25– 37 × 7–9.5 µm, 4-spored, clavate to subcylindric, hyaline. Pleurocystidia 38–74 × 11–20 µm, obovate, sphaeropedunculate, broadly clavate, or fusiform-rostrate, with a long pedicel, with a rounded or mucronate apex, with thin or slightly thickened wall, brown pigmented. Cheilocystidia forming a sterile lamellar edge, 24–80 × 7–15 µm, often narrowly lageniform to abruptly fusiform, very long pedicellate, walls slightly thickened and brown pigmented. Pileipellis an irregular trichoderm with chained elements, these narrowed gradually, hyphae incrusted; terminal cells 45–115 × 9–18 µm, utriform to somewhat conical, less often narrowly lageniform, base generally broad, apices often with a moniliform excrescence, at times rostrate, brownish pigmented. Stipitipellis similar to pileipellis. Clamp connections present, large, and conspicuous. TAXONOMIC NOTES: Albomagister griseosquamosus was previously reported as “undet gray scaly” in Sánchez-García et al. (2014 , 2017 ). This species resembles Tricholoma squarrulosum Bres. and T. atrosquamosum Sacc. , but in its outward appearance A. griseosquamosus differs from these by the more elongated non-bulbous stipe and non-farinaceous odor and taste. Microscopically, A. griseosquamosus differs readily from these by the presence of distinct pleuro- and cheilocystidia and the large conspicuous clamp connections found throughout the all tissues. Fig. 4. Basidiomes of Albomagister luteifolius . (A) HRL2773 (holotype, DAOM 984969). (B) HRL3286 (DAOM 984970). Bars = 1 cm. Photos by R. Lebeuf. Fig. 5. Basidiomes Albomagister subaustralis . (A) MGW1296 (TENN-F-068710). (B) SAT-12–217-02 (TENN-F-067343). Bars = 1 cm. Photo A by M.G. Wood; photo B by S.A. Trudell. The basidiospores of the Quebec collections (6– 6.5 –7.5 × 4– 4.8 –5) µm, Q 1.09 – 1.30 –1.63 are somewhat smaller than the type and ECV5690 from Tennessee . Although not analyzed here, an rpb1 sequence was also produced from the type of A. griseosquamosus —— KU139073 ( Sánchez-García and Matheny 2017 ). ETYMOLOGY: griseosquamosus (Latin) , gray scaly, in reference to the gray scales on the pileus and stipe DISTRIBUTION AND ECOLOGY: Albomagister griseosquamosus apparently is widely distributed in eastern North America, having been found in both Quebec and Tennessee , although there is a broad sampling gap between these regions. It occurs on acidic soils (where known) at relatively low elevations (< 600 m ), in mixed and cove hardwood forests containing some mixture of the following ectomycorrhizal trees: Abies , Fagus , Betula , Tsuga and/or Tilia . Basidiomes have been observed August to September. OTHER SPECIMENS EXAMINED : Canada , Quebec , Saint-Stanislas, Parc de la rivière Batiscan, secteur Murphy, trial Le Buis ( 46.5891 -72.4125 ), solitary on ground in leaf litter in mixed forest under Abies balsamea , Betula alleghaniensis , 7 September 2020 , R. Lebeuf & A. Paul HRL3282 (DAOM 984972); Saint-Alexis-des-Monts, chemin Yvon-Plante ( 46.5099 -73.1955 ), gregarious on soil in northern hardwood forest under Fagus grandifolia , Abies balsamea , Acer , 16 Aug. 2023 , R. Lebeuf & A. Paul HRL4268 (R.L. pers. fung., iNat178773906). USA , Tennessee , Sevier Co., Great Smoky Mountains National Park, Greenbrier, Ramsey Cascades Trail ( 35.7028 -83.3575 ), acidic cove hardwood forest including Tsuga canadensis , Betula alleghaniensis , Tilia americana , Quercus , 5 September 2013 , E. C. Vellinga ECV5690 (TENN-F-068763).