Inonotus sideroxylicola Vlasák & Y.C. Dai, 2013

Vlasák, Josef, Li, Hai-Jiao, Zhou, Li-Wei & Dai, Yu-Cheng, 2013, A further study on Inonotus linteus complex (Hymenochaetales, Basidiomycota) in tropical America, Phytotaxa 124 (1), pp. 25-36 : 32-33

Inonotus sideroxylicola Vlasák & Y.C. Dai , sp. nov. ( Figs. 6 , 7 )

MycoBank MB 803768

Holotype.—USA. US Virgin Islands, St. John Island , on Sideroxylon obovatum , 6 September 2004, J. Vlasák Jr., JV 0409 /30- J (Holotype in PRM 861186 , isotype in JV and BJFC 14698 ).

Etymology.— sideroxylicola (Lat.) : living on Sideroxylon .

Fruitbody. —Basidiomata perennial, pileate, semicircular to dimidiate, ungulate, woody hard when dry. Pilei projecting up to 20 cm, 30 cm wide and 20 cm thick at base. Pileal surface fuscous to black, often with greenish cover of algae in older parts, concentrically zonate and sulcate with about one zone per cm, matted, cracked with age; margin obtuse, fuscous. Pore surface cinnamon to greyish brown when dry, slightly glancing; sterile margin distinct, buff-yellowish to buff, up to 1 mm wide; pores circular, 2–3 per mm; sometimes elongated up to 1 mm, dissepiments thin, entire. Context cinnamon, woody hard, up to 2 cm thick. Tubes cinnamon to yellowish-brown, woody hard, usually with several buff-yellowish context layers,

single layer up to 5 mm, tube layers mostly indistinct.

Hyphal structure. —Hyphal system dimitic both in context and trama; generative hyphae simple septate; tissue darkening in KOH.

Context. —Generative hyphae yellow to golden brown, varying from slightly thick-walled to thick-walled, frequently simple septate, straight, more or less regularly arranged, 3.5–6 Μm in diam.; skeleto-binding alike hyphae present (similar to those in Phellopilus nigrolimitatus ), thick-walled with a narrow lumen, occasionally septate, frequently branched, strongly winding, 1.5–3 Μm in diam.

Tubes. —Generative hyphae hyaline to pale yellowish, thin- to slightly thick-walled, moderately branched, frequently septate, 2.2–3.7 Μm in diam; skeletal hyphae dominant, yellowish brown, thick-walled with a narrow lumen, unbranched, straight, subparallel along the tubes, 3–4 Μm in diam. Hymenial setae rare in the hymenium and dissepiments, mostly subulate, sometimes ventricose, dark brown, thick-walled, 27–35 × 6–8 Μm; cystidioles present, fusoid, 13–19 × 5–7 Μm; basidia clavate to barrel-shaped, with four sterigmata and a simple septum at the base, 10–20 × 6–8 Μm; basidioles in shape similar to basidia, but slightly smaller. Small rhomboid crystals frequently present.

Basidiospores. —Broadly ellipsoid to ellipsoid, usually collapsed when mature, yellowish and thick-walled, smooth, IKI–, CB –, 6–7(–7.2) × (4.2–)4.4–5.1(–5.5) Μm, L = 6.61 Μm, W = 4.76 Μm, Q = 1.38–1.40 (n = 60/2).

Paratypes. —USA. US Virgin Islands, St. John Island , on Sideroxylon obovatum , 4 September 2004, J . Vlasák Jr., JV 0409 /18- J ( JV); 6 September 2004, JV 0409 /32- J ( JV, BJFC 14699 ); 4 July 2012, JV 1207 /4.3- J ( JV).

Notes.— Inonotus sideroxycola is readily distinguished from other species in the I. linteus complex by its large pores, big basidiospores and presence of cystidioles. Morphologically, I. sideroxycola is similar to Fulvifomes rimosus (Berk. in Berkeley 1845: 54) Fiasson & Niemelä (1984: 26), but the latter is a setaless species and its basidiospores are broadly ellipsoid to subglobose ( Dai 2010). In addition, its occurrence in America is questionable.

Figures

FIGURE 6. Basidiocarp of Inonotus sideroxylicola sp. nov. (Holotype).

FIGURE 7. Microscopic structures of Inonotus sideroxylicola sp. nov. (drawn from the holotype). a: Basidiospores; b: Basidia and basidioles; c: Cystidioles; d: Setae; e: Hyphae from trama; f: Hyphae from context.