Poriella subacida (Peck) C.L. Zhao, comb. nov. Figures 3 and 4.

MycoBank number: MB 840062; Index Fungorum number: IF 840062; Facesoffungi number: FoF;

Basionym: Polyporus subacidus Peck, Ann. Rep. N.Y. St. Mus. nat. Hist. 38: 92, 1885.

=Poria subacida (Peck) Sacc., Syll. fung. (Abellini) 6: 325 (1888).

=Chaetoporus subacidus (Peck) Bondartsev & Singer, Annls mycol. 39(1): 51 (1941).

=Oxyporus subacidus (Peck) Komarova, Mycoth. Eston. 3: 13 (1961).

=Perenniporia subacida (Peck) Donk, Persoonia 5(1): 76 (1967).

=Poria colorea Overh. & Englerth, Bull. Yale Univ. School For. 50: 21 (1942).

=Poria fuscomarginata Berk. ex Cooke, Grevillea 15(no. 73): 24 (1886).

=Poria subaurantia Berk. ex Cooke, Grevillea 15(no. 73): 27 (1886).

Fruiting body: Perennial, resupinate to effused-reflex, becomes corky when dried, about 22 cm or more at the longest dimension, 15 cm or more at the widest dimension, and up to 17 mm thick at the center. Pore surface pale yellowish to dingy-yellowish when fresh, dingy-yellowish to pale tan to ochraceous when dry; pores round to angular, 4–6 per mm; dissepiments thin, entire. Subiculum thin, cream to buff, up to 1 mm thick. Tubes concolorous with pore surface, up to 16 mm thick.

Hyphal structure: Hyphal system di-trimitic; generative hyphae with clamp connec- tions; skeletal hyphae strongly dextrinoid, CB+; dissolving in KOH.

Context: Generative hyphae infrequent, hyaline, thin-walled, 2.5–4 µm in diameter; skeletal hyphae dominant, thick-walled with a wide lumen, unbranched, subparallel, 3–5.5 µm in diameter; skeletal-binding hyphae hyaline, thick-walled, frequently branched, flexuous, interwoven, 1–2 µm in diameter.

Tubes: Generative hyphae infrequent, hyaline, thin-walled, 2.5–3.5 µm in diameter; skeletal hyphae dominant, thick-walled with a wide lumen, unbranched, subparallel, 3–4.5 µm in diameter; skeletal-binding hyphae hyaline, thick-walled, frequently branched, flexuous, interwoven, 0.7–1.7 µm in diameter. Cystidia absent, but fusoid cystidioles present, hyaline, thin-walled, 13–16  ×  3–4.5 µm. Basidia barrel-shaped, with four sterig- mata and a basal clamp connection, 20–22.5 × 7–8 µm; basidioles similar in shape to basidia, but slightly smaller.

Basidiospores: Ellipsoid, not truncate, hyaline, thick-walled, smooth, non-dextrinoid, CB+, (4.2–)4.5–6.2(–6.4) × (3.2–)3.6–4.6(–4.9) µm, L = 5.25 µm, W = 3.92 µm, Q = 1.13–1.42 (n = 450/15).

Associated wood-rot: White.

Substrates and distribution: Mainly on conifers, but also on hardwood, causes white rot in Abies Mill and Tsuga Carr. and common on dead fallen trees in many areas. A boreal eastern species in Europe, widely distributed in forest regions of Asia and North America [8,10,11].

Additional specimen examined: CANADA, Ontario, Gull lake, on Thuja occidentalis L., July 25 1919, J.H. Faull (5088) (FH 00605379); Lake Timagami, Timagami Is., on fallen trunk of Abies balsamea (L.) Mill., September 10 1918, J.H. Faull (3365) (FH 00605372); Lake Rosseau, on Tsuga Carr., September 1902, Harper (587) (FH 00605380); Lake Rosseau, on Pinus Linn log, October 1903, S.A. Haper (832) (FH); Lake Rosseau, on fallen log of Abies balsamea (L.) Mill., 18 August 1921, J.H. Faull (6013) (FH 00605381); Humber Valley, on roots of Thuja occidentalis L., September 1914, J.H. Faull (169) (FH 00605373); Humber Valley, on dead hardwood, September 1914, J.H. Faull (156) (FH 00605375); Sudbury District, Cleland Tp., on dead coniferous wood, 15 September 1918, J.H. Faull (3502) (FH 00605377). CHINA, Fujian Province, Wuyishan Nature Reserve, on fallen angiosperm trunk, 21 October 2005, Dai 7316 (IFP); Guizhou Province, Jiangkou County, Fanjingshan Nature Reserve, on fallen angiosperm trunk, 21 August 2010, Yuan 5511 (IFP); Heilongjiang Province, Yichun, Fenglin Nature Reserve, on fallen trunk of Picea Dietr., 2 August 2011, Cui 9849, 9853 (BJFC); Yunnan Province, Baoshan, Gaoligong Mountain, on angiosperm trunk, 23 September 2007, Yuan 3850, 3854 (IFP); Zhejiang Province, Linan, Tianmushan Nature Reserve, on fallen trunk of Picea Dietr., 11 October 2005, Cui 2705 2712 (BJFC). FINLAND, Pera-Pohjanma, Pisavaara National Park, on fallen trunk of Picea Dietr., 14 September 1997, Dai 2648 (BJFC); Pisavaara National Park, on Picea Dietr., 4 November 2011, Dai 12619 (BJFC). USA, Arizona, Coronado National Forest, on conifer, 28 August 1958, Lowe (9407) (FH 00605393); Connecticut, New Haven, Sleeping Giant State Park, on fallen trunk of Betula L., 22 July 2012, Dai 12773 (BJFC); as above, on fallen trunk of Tsuga Carr., 22 July 2012, Dai 12785 (BJFC); as above, 24 July 2012, Dai 10287 (BJFC); as above, on fallen trunk of Pinus Linn, 24 July 2012, Dai 10285 (BJFC); Idaho, Bovill County, on dead fallen trunk of Pinus Linn, 2 October 1920, A.S. Rhoads (15891)(FH 00605391); Priest River, on Picea engelmanni, September 1915, J.R. Weir (9551) (FH 00605392); Priest River, on Abies grandis (Dougl ex D Don) Lindl, September 1915,

J.R. Weir (8152) (FH 00605394); Kansas, Rooks County, Rockport, on underside of old log, 9 December 1893, (1315) (FH 00605389); Maine, Norcross, on fallen Populus L. log, 20 August 1940, D.H. Linder s.n. (FH 00605344), Kittery Point, on log of Quercus L., 28 July 1922, J.R. Weir (897)(FH 00605347); Linekin, on Picea Dietr., September 1899, Burt (2125B) (FH); as above, 16 August 1899, Burt 2127 (FH); Massachusetts, Norfolk County, Sharon, 28 June 1946, A.P.D.Piguet (54) (FH 00605353); Michigan, Neebish, September 1911, E.T.Harper & S.A.Harper s.n. (FH 00605383); Isle Royal, Rock Harbor, August 1904, E.T.Harper & S.A.Harper s.n. (FH 00605384); Pleasant Ridge, on fallen Tsuga Carr., 25 September 1915, P.Spaulding & J.F.Collins s.n. (FH 00605345); New York, Osceola, on Tsuga Carr., August 1885, C.H. Peck, BPI 844697 (Holotype, BPI); as above, on Picea Dietr. log, FH 0053717 (FH);

Dryden, Ringwood Preserve, on old wood, 9 June 1952, W.B.Cooke & V.G.Cooke (29105) (FH 00605356); Ithaca, on Betula lutea F.Michx., nom. illeg. 21 March 1935, W.L. White (1568) (FH 00605360); Floodwood, on conifer, August 1900, Burt 2122B (FH); Floodwood, on Picea Dietr. log, 20 August 1900, 2123B (FH); Pennsylvania: Bedford County, New Paris, on fallen Quercus L., 1 September 1916, J.H. Faull (1490) (FH 00605366); Lackawanna County, Carbondale, on Tsuga Carr. log, 13 December 1898, Burt 2124C (FH); Tennessee, Knox County, Ball Camp Pike, on Pinus Linn log, 18 December 1938, L.R. Hesler (11907) (FH 00605387); Vermont: Addison County, Ripton, on hardwood log, 31 October 1896, (FH 00605346); Addison County, Ripton, on Picea Dietr., 4 November 1896, Burt 2126A (FH); Addison County, Ripton, on Picea Dietr., 31 October 1896, Burt 2126B (FH); Abby, on Tsuga Carr. log, 31 October 1896, Burt 2123A (FH); Underhill, on hardwood, 18 May 1880, Pringle (1025) (FH 00605350); as above, on dead conifer, August 1897, Burt 2121A, B, C (FH); as above, on fallen trunk of Tsuga Carr., September 1902, Harper 625 (FH); Dunamase, on Tsuga Carr. log, 14 September 1896, Burt 2121E (FH); Dunamase, on Tsuga Carr., October 1896, Burt 2122A (FH); Snake Mountain, January 1896, 2124A (FH); as above, September 1902, Harper 746 (FH); Washington: Marymere Falls, Olympic National Park, on Pseudotsuga taxifolia (Lamb.) Britton, WB (27590) (FH 00605395); Clallam County, Sol Duc Hot Springs, on fallen Tsuga heterophylla (Raf.) Sarg., 4 July 1920, J.R. Weir (650) (FH 00605396); as above, on fallen trunk of Picea sitchensis (Bong.) Carr., 14 July 1920, J.R. Weir (609) (FH 00605397); Wisconsin, June 21 1946, Neuman (162) (FH 00605386).

Figure 3. Basidiomata of Poriella subacida (Holotype, BPI 844697). Scale bar = 1 cm.

Figure 4. Microscopic structures of Poriella subacida (Holotype). (a) Basidiospores. (b) Basidia and basidioles.  (c) Cystidioles.  (d) Hyphae from trama.  (e) Hyphae from context.  Bars:  A = 5 µm; B–E = 10 µm.