Favolaschia xtbgensis Karunarathna & Nimalrathna, 2022

Nimalrathna, Thilina S., Tibpromma, Saowaluck, Nakamura, Akihiro, Galappaththi, Mahesh C. A., Xu, Jianchu, Mortimer, Peter E. & Karunarathna, Samantha C., 2022, The case of the missing mushroom: a novel bioluminescent species discovered within Favolaschia in southwestern China, Phytotaxa 539 (3), pp. 244-256 : 248

Favolaschia xtbgensis Karunarathna & Nimalrathna sp. nov. Figs. 1 , 3

Index Fungorum number: IF559348

Etymology: The species epithet “xtbgensis” refers to the place “Xishuangbanna Tropical Botanical Garden” where the type species was collected.

Holotype:— HKAS 121667

Diagnosis:— This new species can be distinguished from other taxa in the genus Favolaschia by white to grayish lilac, translucent, smooth and spongy pileus; 1 × 2 mm size 180–200 pores in hymenophore; 8.2–10.4 × 6.1–8.2 μm size basidiospores; 30–44 × 10–13 μm size basidia and the absence of cheilocystidia and pleurocystidia.

Pileus 5–12 mm diam., plano-convex, surface white to grayish lilac, translucent, smooth, spongy, margin not entire. Hymenophore poroid, outermost pores close to the margin are smaller than the center, mostly hexagonal, pores 1 × 2 mm in size, 180–200 in number/hymenophore. Stipe concolorous with pileus, short, 2–4 mm long, 1–2 mm in diameter, lateral, eccentric, cylindric, surface smooth. Context white and thin. Spore print white.

Luminescence. Emitting soft green light in the fruit bodies, spore print and the mycelium of the fruit bodies ( Fig. 1B ).

Basidiospores 8.2–10.4 × 6.1–8.2 μm (Q =1.27, total number of spores examined = 50), subglobose, white, spore surface rough, large oil drop inside. Basidia ( Fig. 3A ) 30–44 × 10–13 μm, clavate, 4 spored, sterigmata 6–7 × 1–2μm. Hymenophore edge fertile, cheilocystidia and pleurocystidia absent. Gloeocystidia and Acanthocystida absent. Pileal trama ( Fig. 3B ) composed of thin-walled, gelatinized, filamentous hyphae, 7–10 μm in diameter, branched. Clampconnections present.

Ecology and distribution:— Caespitose, growing up to 20–30 fruit bodies, Southwest China (Yunnan Province, Menglun City), June to September.

Material examined:— CHINA. Yunnan Province, Menglun City, 26°54’50.58”N 99°46’50.76”E, elev. 550 m, on dead bamboo, 21 July 2021, Thilina Nimalrathna ( HKAS 121667, holotype).

Additional specimen examined: — CHINA. Yunnan Province, Menglun City, 26°54’50.58”N 99°46’50.76”E, elev. 550 m, on dead bamboo, 22 July 2021, Thilina Nimalrathna ( HKAS 121975, paratype).

Figures

FIGURE 1. Fruit bodies of Favolaschia xtbgensis in the field, at night. A. Photographed with the aid of a flashlight. B. Photographed in complete darkness. Scale bars: A, B=10 mm.

FIGURE 3. Microscopic structures of Favolaschia xtbgensis (HKAS121667, holotype). A. Hyphae at edge of pores showing basidia. B. Hyphae of pileus cortex. C. Basidiospores under SEM. D. Upper view of a basidium with sterigmata and young basidiospores under SEM. Scale bars: A=20 μm; C, D=10 μm.