Four new species of Albomagister (Agaricales) from eastern North America Matheny, P. Brandon Lebeuf, Renée Sánchez-García, Marisol Graddy, Mary G. Trudell, Steven A. Wood, Michal G. Vellinga, Else C. Botany 2024 2024-09-01 102 9 355 365 Matheny, Sanchez-Garcia & Vellinga Matheny, Sanchez-Garcia & Vellinga 2024 Agaricomycetes Tricholomataceae Albomagister Fungi Agaricales 6 361 Basidiomycota species parviniveus sp. nov.  MYCOBANK: MB851402.   TYPE:  USA, Tennessee, Sevier County, Great Smoky Mountains National Park, Cherokee Orchard, last turn-off before Rainbow Falls( 36.1328 -83.8144), on acidic soil in cove hardwood forest near  Tsuga canadensis,  Pinus,  Quercus,  31 August 2013,  E.C. VellingaMSG144( holotypedesignated here, TENN-F-071074).  DIAGNOSIS: Differs from other  Albomagisterby the absence of pleurocystidia, small basidiome size, and occurrence in eastern North America. Differs from  A. virgineusby the slightly smaller spores, none of which are dextrinoid, and occurrence in acidic cove hardwood forests of eastern North America.   Habitsmall, mycenoid to inocyboid. Pileusup to 15 mmwide, convex, whitish, smooth, dry. Lamellaeadnexed, close, whitish. Stipe20 × 2 mm, slightly enlarged at the base; surface dry, fibrillose, off-white. Basidiospores5– 5.3–6(– 6.5) × 4– 4.7–5.5 µm, Q 1.08– 1.16–1.28 ( n= 40/1), subglobose to broadly elliptic, with a guttule, hyaline, inamyloid and nondextrinoid, with a distinct apiculus, white in deposit. Basidia24–29 × 6–8 µm, 4-spored, narrowly clavate to subcylindric, hyaline. Pleurocystidiaabsent. Cheilocystidia24– 52 × 5–7.5 µm, cylindric to narrowly utriform, at times narrowly clavate-flexuous, very long pedicellate, forming a sterile lamellar edge. Pileipellishyphae slightly interwoven with some tips projecting upwards; terminal hyphae 55–98 × 6– 9 µm, these narrowly cylindric to somewhat clavate-fusiform, hyaline, apices generally obtuse (rarely rostrate). Stipitipelliswith scattered terminal cells 15–39 × 6–8 µm, these cylindric to clavate, smooth, thin-walled, hyaline. Clamp connectionspresent in all tissues.  TAXONOMIC NOTES:  Albomagister parviniveusis the same as “undet small white” in Sánchez-García et al. (2014, 2017). The species is distinguished from other American  Albomagistermost notably by the very small basidiomes and absence of pleurocystidia. We have only observed this species twice over a span of 15 years, but on both occasions at Cherokee Orchard in the Great Smoky Mountains National Park. The species is sister to the European  A. virgineus, which also lacks pleurocystidia; however, it differs from  A. parviniveusby the slightly larger spores with occasional dextrinoid walls and occurrence in a boxwood (  Buxus) habitat in France.  ETYMOLOGY:  parviniveus(Latin), small and white, in reference to the small white basidiomes.  DISTRIBUTION AND ECOLOGY:  Albomagister parviniveusis known only from the typelocality in the Great Smoky Mountains National Park where it has been collected in two different years. This species occurs singly on acidic soils in cove hardwood forests near  Tsuga,  Quercus,  Betula, and  Pinus. Basidiomes were observed in August.  ADDITIONAL SPECIMENS EXAMINED: USA, Tennessee, Sevier County, Great Smoky Mountains National Park, Cherokee Orchard Loop Road ( 35.6758, −83.4861), on ground in cove hardwood forest near  Tsuga canadensis,  Quercus,  Betula,  Pinus, 6 August 2009, M.B. PilkingtonMBP6.VIII.09 (TENN-F-064359). 5209581304 on acidic soil in cove hardwood forest near Tsuga canadensis, Pinus, Quercus 2013-08-31 E. C. Vellinga United States of America Sevier County 36.1328 Great Smoky Mountains National Park, Cherokee Orchard, last turn-off before Rainbow Falls 6 -83.8144 6 361 TENN-F-071074 1 Tennessee holotype