Pluteus pellitus Justo, Malysheva, Bulyonkova, Vellinga, Cobian, Nguyen, Minnis & Hibbett, 2014, sp. nov.

Pluteus pellitus (Persoon: Fries) Kummer (1871: 98). Fig. 25

Basionym: Agaricus pellitus Persoon (1801: 366); Agaricus pellitus Persoon: Fries (1821: 198). Neotype (Bonnard 1995):— FRANCE. Môle, 31 July 1960, R. Kühner SA-60-2 (G-K!).

Synonym: Pluteus sandalioticus Contu & Arras (2001: 137). Neotype (Justo et al. 2006):— SPAIN. Sevilla, Cazalla de la Sierra, La Atalaya, on decayed wood of Quercus suber, 21 March 2002, N. Rodriguez-Ramos s.n. COFC-F 2959 (COFC!).

Pileus 30–75(–130) mm in diameter, hemispherical or campanulate when young, expanding to convex or planoconvex, with or without a low, broad umbo; surface smooth or innately radially fibrillose, usually with well-defined squamules at center; brown at center (7.5YR 4/4–4/6) and much paler towards margin (7.5YR 7/4–7/8) or white all over; dry or slightly viscid when moist; margin smooth or slightly translucent-striate. Lamellae crowded, free, ventricose, up to 7 mm broad, white when young, later pink, with even, or white, flocculose edges. Stipe 35–70 × 5–15 mm, cylindrical, with slightly broad base; surface white, smooth or with longitudinal brown or gray-brown fibrils especially near the base. Context in stipe and pileus white. Smell indistinct. Taste indistinct. Spore print not recorded.

Basidiospores [140, 5, 5] 5.0–7.5(–8.0) × 3.5–5.0(–5.5) µm, avl × avw = 5.8–6.5 × 4.3–4.6 µm, Q = 1.24–1.71, avQ = 1.34–1.46, broadly ellipsoid, ellipsoid or oblong, sometimes ovoid or slightly constricted in the middle. Basidia 15–32 × 6–10 µm, tetrasterigmate, clavate, some with median constriction. Pleurocystidia metuloid, 50–95 × 12–25 µm, fusiform, narrowly fusiform or narrowly utriform, provided with 2–4 apical hooks, rarely fusiform and without hooks at apex, a few with lateral hooks (usually entire), hyaline, with up to 3 µm thick wall, frequent all over lamellar faces. Intermediate cystidia similar to the pleurocystidia but smaller and/or with thinner walls, a few irregularly shaped, without distinct apical hooks and/or with rounded apices; in some collections fusiform cystidia and cystidia with no hooks dominate, in others there is no predominant morphological type. Lamellar edge sterile. Cheilocystidia 34–100(–115) × 10–27 µm, clavate, narrowly clavate or cylindrical (either type predominant), a few spheropedunculate, hyaline, crowded, forming a well-developed strip. Pileipellis a cutis, with terminal elements 60–165 × 7–25 µm; individual elements cylindrical, usually strongly tapering towards apex, hyaline or filled with brown intracellular pigment, with thin, smooth walls. Stipitipellis a cutis; hyphae 5–20 µm wide, cylindrical, hyaline or with brown intracellular pigment, with thin, smooth walls. Clamp-connections common and readily seen on pileipellis hyphae but not at every septum; also observed in other parts of the basidiocarp.

Habit, habitat and phenology:—Solitary or subgregarious, growing on well-decayed wood of hardwoods (e.g. Quercus, Eucalyptus) more rarely terrestrial. In temperate or Mediterranean forests, also in Eucalyptus plantations. May–November.

Distribution:— Eurasia. France, Italy, Spain, South-western Russia.

Observations:—The present concept of P. pellitus is in agreement with the neotypification made by Bonnard

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(1995) that defines P. pellitus as a species with relatively small basidiospores, with clamp-connections in the pileipellis and growing on angiosperm wood or terrestrial. For a detailed discussion about this species and its different interpretations see Vellinga (1987), Bonnard (1995) and Justo & Castro (2007b). In the field it can be confused with white variants of other species, and the name has been variously misapplied. Pluteus pellitus is restricted to Europe.

Collections corresponding to the morphological concept of P. sandalioticus (Contu 2001; Justo et al. 2006), with pigmented pileus and longer cheilocystidia, fall within the molecular variation of P. pellitus (coll. AJ200, AJ60; Fig. 5a).

Additional collections examined: — ITALY. Sardinia: Olbia-Citta, urban park, apparently terrestrial, 25 May 2008, M. Contu s.n. AJ 72, nrITS HM562036, tef1 KJ009988 (LOU). RUSSIA. Southern Federal District: Krasnodarsky Territory, broadleaf forest (Quercus, Carpinus), 23 June 1974, A.E. Kovalenko s.n. LE 9686, nrITS KJ009700, tef1 KJ009990 (LE); ibid., Stanitsa Kaluzhskaya, Quercus forest, on stump, 19 September 1979, A.E. Kovalenko s.n. LE 9687, nrITS KJ009699, tef1 KJ009983 (LE). Volga Federal District: Samara Region, Zhigulevsky Nature Reserve, vicinities of Bakhilova Polyana, broadleaf forest, on fallen trunk of deciduous tree, 08 August 2000, E.F. Malysheva s.n. LE 289374, nrITS KJ009698, tef1 KJ009984 (LE). SPAIN. Huelva: Los Romeros, Quercus forest, on decayed wood of Quercus, 06 November 2003, J. Siquier s.n. AJ 60, nrITS HM562107, tef1 KJ009986 (MA). La Rioja: Villaroya, Quercus forest, on decayed wood of Quercus ilex, 20 October 2011, A. Caballero s.n. AJ 200, nrITS HM562052, tef1 KJ009989 (LOU). Pontevedra: Vigo, urban park, apparently terrestrial, October 2008, A. Justo 74, nrITS HM562047, tef1 KJ009985 (LOU). Sevilla: mixed forest, on decayed wood of Alnus glutinosa, March 2003, N. Rodriguez s.n. AJ 202, nrITS HM562037, tef1 KJ009987 (LOU).

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Pluteus leucoborealis Justo, E.F. Malysheva, Bulyonkova & Minnis, sp. nov. Fig. 26

MycoBank 808732

Diagnosis:—Differs from Pluteus petasatus in the comparatively larger basidiospores and in the boreal distribution. 58 Phytotaxa 180 (1) © 2014 Magnolia Press

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Holotype:— RUSSIA. Siberian Federal District: Krasnoyarsky Kray, Turukhansky District, right bank of Yenisei River, on decayed Betula trunk, 26 August 2009, A. V. Aleksandrova s.n. LE 289421, nrITS KJ009746, tef1 KJ009994 (LE!).

Etymology:— leucoborealis is a combination of the Greek “λευκοϛ” (white or pale) and the Latin borealis (derived from the Greek “βορειος” meaning northern), making reference to the external aspect and distribution of this species.

Pileus 20–60(–80) mm in diameter, hemispherical or campanulate when young, expanding to convex or planoconvex, with or without a low, broad umbo; surface completely smooth, squamose-fibrillose only around center, with radial fibrils all over (sometimes forming a star-shaped pattern) or with distinct brown squamules all over; pure white but fibrils and squamules (when present) are brown or gray-brown (7.5YR 7/2–7/6, 6/2–6/8); slightly to distinctly viscid when moist; margin smooth or translucent-striate. Lamellae crowded, free, ventricose, up to 8 mm broad, white when young, later pink, with even, or white, flocculose edges. Stipe 30–80 × 3–8 mm, cylindrical with slightly broad base; surface white, or yellowish near base, usually with distinct gray-brown squamules and fibrils near the base or all over, more rarely smooth. Context in stipe and pileus white. Smell indistinct. Taste indistinct. Spore print pink to pinkish brown.

Basidiospores [90, 3, 3] (5.5–)6.0–8.0(–8.5) × (4.5–)5.0–6.0 µm, avl × avw = 6.8–7.4 × 5.3–5.5 µm, Q = 1.17–1.50, avQ = 1.26–1.36, ellipsoid or broadly ellipsoid, sometimes ovoid or slightly constricted in the middle. Basidia 14–28 × 5–10 µm, tetrasterigmate, clavate, some with median constriction. Pleurocystidia metuloid, 40–93 × 10–30 µm, fusiform, narrowly fusiform or narrowly utriform with 2–3(–4) apical hooks (usually entire, sometimes bifid or poorly developed), some fusiform and without apical hooks, sometimes this later type is predominant, some with small lateral hooks, hyaline, with up to 3 µm thick wall, frequent all over lamellar faces. Intermediate cystidia in most collections predominantly fusiform and without apical hooks, some similar to the pleurocystidia but smaller and/or with thinner walls. Lamellar edge sterile. Cheilocystidia 30–72(–85) × 10–23 µm, the majority narrowly clavate or clavate, a few cylindrical or narrowly utriform, hyaline, thin-walled, forming a well-developed strip, more rarely scarce and scattered. Pileipellis a cutis or ixocutis, with terminal elements 85–140(–170) × 7–17 µm; individual elements cylindrical, some strongly tapering towards apex, hyaline or filled with brown intracellular pigment, with thin, smooth walls; in some collections a gelatinous matrix is present in the most external part, with embedded hyphae 2–5 µm wide, some with irregular outline. Stipitipellis a cutis; hyphae 5–25 µm wide, cylindrical, hyaline or with brown intracellular pigment, with thin, smooth walls. Clampconnections absent on pileipellis hyphae; in some collections present (but very scarce) in pileitrama, hymenophoral trama and/or stipitipellis.

Habit, habitat and phenology:—Commonly gregarious, more rarely solitary. Growing on decayed wood of Betula, more rarely Alnus. In boreal or transitional boreal/temperate forests. June–September.

Distribution:— Eurasia. Widespread from north-western Russia to Siberia. North America:—Widespread. In the East recorded from the northern parts of Michigan (Emmet Co., Tahquamenon Falls) and New York (Adirondacks). In western North America, only recorded from Alaska.

Observations:— Pluteus leucoborealis resembles externally P. petasatus, and has a similar degree of extensive morphological variation. Basidiospore size is the most reliable character to tell both species apart. P. leucoborealis has usually a well-developed strip of cheilocystidia but this character is less reliable than basidiospore size.

Pluteus leucoborealis is widespread geographically, from the St. Petersburg area in Russia to the Adirondacks in New York, but seems to be confined to boreal or transitional forests, and has not been recorded in geographically close but ecologically different areas like the temperate forests of western Europe or eastern North America. It has a strong preference for wood of Betula and Alnus.

Pluteus glaucus (Singer 1961a: 114) can also have very pale and squamulose pileus but it differs from P. leucoborealis in the presence of bluish green tinges on the pileus, the pigmented lamellar edges, the much smaller cheilocystidia (up to 27 µm long) and the abundant clamp-connections. This species is only known from Chile (Singer 1961a).

Additional collections examined: — MONGOLIA. North Mongolia, Research Station “Khonin Nuga”, Mandal Sum, Selenge Aimak West-Khentee, riparian Betula-Picea forest, on fallen Betula trunk at site of fire, 14 August 2007, A.V. Aleksandrova s.n. LE 289424, nrITS KJ009743, tef1 KJ009999 (LE). RUSSIA. Far East Federal District: Primorsky Territory, Ussuriisky Nature Reserve, vicinities of Peishula Reserve Field Station, floodplain Ulmus forest, on decayed wood of Alnus, 13 August 2011, E.F. Malysheva s.n. LE 289373, nrITS KJ009734, tef1 KJ009992 (LE). Northwestern Federal District: Leningrad Region, Luzhsky District, Shalovo- Perechinsky Reserve, Picea forest with isolated Betula and Quercus, on fallen trunk of Betula, 21 August 1997, O.V. Morozova s.n. LE 216010, nrITS KJ009744, tef1 KJ009991 (LE). Leningrad Region, Vyborgsky District, vicinities of Lebedevka, Betula forest, on decayed wood of Betula, 24 July 1997, O.V. Morozova s.n. LE 215340,

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nrITS KJ009742, tef1 KJ010002 (LE); ibid., vicinities of Roschino, “Lindulovskaya Roscha” Reserve, on fallen trunk of Alnus, 09 June 1995, E.A. Fomina s.n. LE 289364, nrITS KJ009748, tef1 KJ010001 (LE). Novgorod Region, vicinities of Syuiska, mixed forest, on fallen trunk of Betula, 04 July 2011, S. Arslanov s.n. LE 289375, nrITS KJ009745, tef1 KJ010000 (LE). Pskov Region, Sebezhsky District, National Park “Sebezhsky”, bank of Midino Lake, Picea forest, on fallen trunk of Betula, 23 July 2002, O.V. Morozova s.n. LE 217548, nrITS KJ009739 (LE). St Petersburg, Primorsky District, “Yuntolovsky” protected area, mixed forest (Pinus, Betula), on fallen trunk of Betula, 08 September 2004, O.V. Morozova s.n. LE 234709, nrITS KJ009751 (LE). Siberian Federal District: Baikal region, Barguzinsky Nature Reserve, conifer forest (Pinus, Larix), on fallen trunk, 10 August 1969, E.L. Nezdoiminogo s.n. LE 9808, nrITS KJ009749, tef1 KJ010006 (LE). Novosibirsk Region, Novosibirsk District, Akademgorodok, planted Betula pendula grove with many fallen trees and dense shrub undergrowth, on Betula, rotten trunk, 19 July 2011, T.M. Bulyonkova s.n. LE 289399, nrITS KJ009741, tef1 KJ010004 (LE). ibid., mixed forest (Betula pendula, Pinus sylvestri s), on Betula, rotten wood, 14 August 2007, T.M. Bulyonkova s.n. LE 289419, nrITS KJ009747, tef1 KJ009995 (LE); ibid., planted Betula pendula grove ca. 40 years old with dense shrub undergrowth and relatively scarce grassy vegetation, on rotten trunk, 05 July 2011, T.M. Bulyonkova s.n. LE 289405, nrITS KJ009735, tef1 KJ009993 (LE). Tyumen Region, Berezovsky, Pripolarny Village, on fallen trunk of Betula at a burn site, 30 June 2010, E. Zvyagina s.n. LE 235802, nrITS KJ009736, tef1 KJ010007 (LE). Ural Federal District: Yugra, Khanty-Mansiykiy District, Shapsha Village, mixed dark conifer taiga (Picea obovata, Abies sibirica, Pinus sibirica with scarcer Betula pendula, Populus tremula, Pinus sylvestris), on decayed wood, 04 August 2007, N.V. Filippova s.n. LE 289402, nrITS KJ009740, tef1 KJ010003 (LE). Yugra, Khanty-Mansiyskiy District, Mukhrino Field Station of the Ugra SU UNESCO chair, mixed dark conifer taiga (Picea obovata, Abies sibirica, Pinus sibirica with scarcer Betula pendula, Populus tremula, Pinus sylvestris), on rotten trunk of deciduous tree, 25 July 2009, N.V. Filippova s.n. LE 289408, nrITS KJ009737, tef1 KJ009996 (LE). UNITED STATES OF AMERICA. Alaska: Fairbanks North Star Borough, Fairbanks, Large Animal Research Station, on decayed wood of Betula, 05 August 2011, MSA Foray pak-2, nrITS KJ009732 (BPI); ibid., on decayed wood of Betula, 05 August 2011, A.M. Minnis pak-1, nrITS KJ009750, tef1 KJ010009 (BPI). Michigan: Chippewa Co., Tahquamenon Falls State Park, on unidentified wood of broadleaf tree, 03 September 1953, A.H. Smith 42452, nrITS HM562060, tef1 KJ009997 (MICH). Emmet Co., Hemlock Bog, on wood, 14 September 2007, J. Steinke SF5-BPI 882768, nrITS HM562177, tef1 KJ010005 (BPI). New York: Essex Co., Adirondack Ecological Center, Huntington Wildlife Forest, mixed forest, on decayed wood, 17 August 2012, O. Miettinen s.n. AJ 587, nrITS KJ009738, tef1 KJ010008 (CUW); ibid., on decayed wood of hardwood, 16 August 2012, O. Miettinen s.n. AJ 595, nrITS KJ009733, tef1 KJ009998 (CUW).

V. salicinus clade. Fig. 6

Species growing on angiosperm wood (P. salicinus, P. americanus, P. saupei) or on conifer wood (P. sepiicolor, P. oreibatus). Blue-green, or blue-gray tinges common on pileus, stipe and/or context. Clamp-connections common and easy to spot on pileipellis hyphae. For additional information on tropical and subtropical taxa belonging in the salicinus clade see Justo et al. (2011 a, 2011b).