Megasporia insularis Melo, Salcedo, C.A. Garcia & Olariaga, 2023

Melo, Ireneia, Salcedo, Isabel, Garcia, Cesar A. & Olariaga, Ibai, 2023, Two new species of resupinate poroid fungi (Basidiomycota, Polyporaceae) from São Tomé and Príncipe Archipelago, Phytotaxa 607 (1), pp. 41-56 : 48-50

Megasporia insularis Melo, Salcedo, C.A. Garcia & Olariaga , sp. nov. ( Figs. 3 , 4 )

MycoBank No: MB 843724

Type:— SÃO TOMÉ AND PRÍNCIPE. Príncipe Island: at the foot of Pico Mesa , 319 m, 1°35ʹ10.72ʺ N 7°21ʹ26.47ʺ E, 22 November 2016, on unidentified hard wood, C.A. Garcia & J. R. Shevock, LISU 254186 ! (holotype) .

Description:—Basidiome annual, resupinate, effused, strongly adnate, hard, up to 1.5 mm thick; pore surface light cream (10YR 8/3–8/4), colour unchanged when dry, pores round to angular, entire, 1–2 per mm, pore edges sterile; tubes shallow, up to 0.4–0.5 mm deep, originating as isolated depressions in the marginal tissue; hyphal pegs absent; context and trama cream, dense in the structure; hymenium whitish, restricted to the base of the tubes; margin 1–1.5 mm, broad, sterile, concolorous to pore surface. Hyphal system dimitic, with clamped generative hyphae; generative hyphae 1.5–3 µm diam., hyaline, thin-walled; skeletal hyphae 2–4 µm diam., hyaline, thick-walled to solid, with strong dextrinoid reaction in Melzer, acyanophilous, abundant in context and trama, unbranched or more or less arboriform, apically acuminate in the sterile margin of dissepiments. Dendrohyphidia easy to observe in the edge of dissepiments, thin-walled, hyaline, arising from the end of generative hyphae; hymenial dendrohyphidia up to 30 µm long, thin-walled, branched at the apex. Cystidia absent but presence of hymenial cystidioles, up to 30 × 6 µm, more or less fusiform, thin-walled. Basidia 25–30 × 9–11 µm, clavate, sometimes with a slight median constriction, with 2 or 4 sterigmata up to 6 µm long. Basidiospores 12–14 × 4.5–5 µm, subcylindrical, thin-walled, smooth, hyaline, non-amyloid, with or without oil drops in the cytoplasm.

Etimology:— insularis , deriving from latin insula (island), refers to the geographical location where the material was collected, an island.

Notes:— Megasporia insularis is well characterized by its large, regular pores, 1–2/ mm, presence of dendrohyphidia, absence of hyphal pegs, and subcylindrical basidiospores, 12–14 × 4.5–5 µm. The new species shares with M. cavernulosa the presence of dendrohyphidia and the absence of hyphal pegs, but the former differs in having narrower basidiospores, 4.5–5 µm broad, and hymenophore with larger pores. The rest of the species included so far in the genus lack dendrohyphidia and differ from each other mainly by the presence or absence of hyphal pegs, spore size, and number of pores per/mm. The new species M. insularis differs from M. amazonica and M. cylindrospora by the presence of dendrohyphidia and by having wider basidiospores, 12–14 × 4.5–5 µm. The species M. amazonica and M. cylindrospora both share the absence of dendrohyphidia but differ in basidiospore size, 10–12 × 3.5–4 µm and 12–13 × (2–)3–4 µm respectively (see key 1).

Figures

FIGURE 3. Megasporia insularis (holotype LISU 254186). Basidiome.

FIGURE 4. Megasporia insularis (holotype LISU 254186). a) generative hyphae; b) skeletal hyphae; c) dendrohyphidia and hyphae from the edge of dissepiments; d) hymenial dendrohyphidia; e) cystidioles; f) basidia and crystals; g) basidiospores. Drawing by I. Melo.