Megasporia rimosa Y. Yuan, X.H. Ji & Y.C. Dai

Yuan, Yuan, Ji, Xiao-Hong, Chen, Jia-Jia & Dai, Yu-Cheng, 2017, Three new species of Megasporia (Polyporales, Basidiomycota) from China, MycoKeys 20, pp. 37-50 : 40

Megasporia rimosa Y. Yuan, X.H. Ji & Y.C. Dai sp. nov. Figure 2

Diagnosis.

Differs from other Megasporia species by its extremely thin and cracked basidiocarp (less than 0.5 mm thick) when dry.

Holotype.

CHINA. Guangxi Auto. Reg., Shangsi County, Shiwandashan Nature Reserve, on fallen angiosperm branch, 06 June 2015, Y.C. Dai 15357 (BJFC019468).

Basidiocarps.

Annual, resupinate, corky, without odor or taste when fresh, becoming hard corky and cracked upon drying, up to 17 cm long, 4 cm wide, and 0.4 mm thick at centre. Sterile margin thinning out, white when fresh, cream when dry, very narrow to almost lacking. Pore surface white to cream when fresh, cream when dry; pores angular, 3-4 per mm; dissepiments thick, entire. Subiculum pale buff, corky, up to 0.1 mm thick. Tubes cream, paler than subiculum, corky, up to 0.3 mm long.

Hyphal structure.

Hyphal system dimitic; generative hyphae bearing clamp connections; skeletal hyphae weakly dextrinoid, CB+; tissues unchanged in KOH.

Subiculum.

Generative hyphae infrequent, hyaline, thin-walled, occasionally branched, sometimes encrusted by crystals, 1.5-2.5 µm in diam; skeletal hyphae dominant, thick-walled with a narrow to medium lumen, moderately branched, mostly flexuous, interwoven, slightly gelatinized, sometimes encrusted by crystals, 2.5-3.5 µm in diam.

Tubes.

Generative hyphae hyaline, thin-walled, occasionally branched, 1.5-2.5 µm in diam; skeletal hyphae dominant, thick-walled with a narrow lumen, unbranched, more or less straight, subparallel along the tubes, 2-3 µm in diam. Hyphal pegs absent, dendrohyphidia present along hymenium, cystidia absent; cystidioles present, mostly ventricose, thin-walled, smooth. Basidia broadly clavate to pear-shaped, with four sterigmata and a basal clamp connection, 20-28 × 5-7.5 µm; basidioles in shape similar to basidia, but smaller. Small tetrahedric or polyhedric crystals frequently present among subhymenium and hymenium.

Spores.

Basidiospores cylindrical, hyaline, thin-walled, smooth, sometimes with one or two guttula, IKI–, CB–, (16.5 –)16.8–20.2(– 21) × (4.1 –)4.3–5.5(– 5.9) μm, L = 18.49 μm, W = 4.88 μm, Q = 3.97 (n = 30/1).

Etymology.

Rimosa (Lat.): referring to the cracked hymenophore when dry.