From Ryvarden & Johansen’s A Preliminary Polypore Flora of East Africa, 1980.
HEXAGONIA HYDNOIDES (Fr.) M. Fidalgo
Mem. New York Bot. Gard. 17(2):35-108, 1968.- Polyporus hydnoides Fr. Syst. Mycol. 1:362, 1821 – Boletus fibrosus Hook. in Kunth., Syn. Pl. 1:10, 1822 (K:).
FRUITBODY annual, rarely perennial, pileate, solitary to imbricate, narrowly attached to the substrate by a thick and small pilear portion, 3-19 cm broad, 2.5-10(14) cm wide and 0.2-1(2) cm thick, but usually thin. Consistency more flexible and coriaceous when fresh, rigid on drying. PILEUS dimidiate to flabelliform, convex or flat, upper surface dark brown to almost black, first densely covered with up to 6 mm long dark branched hairs, erect or prostrate, soon falling off completely or in concentric zones, rarely glabrous, but often shiny. Margin thin, acute, entire or slightly incised and lobed, concolorous with the surface. PORE LAYER fulvous to dark brown with a distinct greyish tint, pores round to somewhat irregular, 3-4(5) per mm, dissepiments thick and entire, tubes pruinate, brown to grey, single-layered, occasionally with a few indistinct layers 0.1-0.5(1) cm long. CONTEXT cinnamon-brown to dark brown, darkening in KOH, 1-10(14) mm thick, but usually very thin.
HYPHAL SYSTEM trimitic, generative hyphae hyaline, thinwalled and clamped, 2-2.5 µm wide, early collapsed and not easy to demonstrate, skeletal hyphae yellow to pale brown, thick-walled, sometimes with few secondary simple septa, 3-6 µm wide. Binding hyphae hyaline to yellowish with slightly thickened walls, weakly to heavily branched 1.5-2.5 µm in diameter. The pilear hairs are dominated by parallel yellowish-brown skeletal hyphae. CYSTIDIA, cystoid hyphae and pseudo-setae absent. SPORES cylindrical, hyaline, smooth and thin-walled (9)11-13.5(15 x (3)3.5-4.5(5) µm, nonamyloid.