Lentinus megacystidiatus Karun., K.D. Hyde & Zhu L. Yang
Index Fungorum number 518277 ; MycoBank: 518277
Pileus (Fig.1) 0.6–2 cm in diameter, thin, convex, coriaceous, umbilicate to infundibuliform; margin inflexed, entire, thin at first reflexed, involute at maturity; surface grayish orange (5B4), dry, uniformly velutinous to slightly long-hispid or subsquamulose furfuraceous, zonate, densely ciliate; hairs dark brown (6F7). Lamellae arcuate, deeply decurrent, up to 0.25 mm wide, crowded with 6 tiers of lamellulae, grayish orange (5B4), with entire edge. Stipe 0.2–1.4 cm×2–4 mm, central, excentric, rarely lateral, cylindrical, slender, solid, yellowish brown (5E8), uniformly and persistently velutinous, with dark brown (6F7) hairs; context 2–3 mm, white in color, consisting of a dimitic hyphal system with generative and skeletal hyphae. Generative hyphae 5–6 μm diameter, hyaline, very thin walled, frequently branched, with prominent clamp connexions. Skeletal hyphae 9–10 μm diameter, hyaline with a thickened wall, unbranched or with an occasional short, lateral branch, either terminal or intercalary in origin. Basidiospores (Fig. 2a) 6–8×3–4 μm (n=40, Lm=6.37 μm, Wm= 3.6 μm, Q=1.50–2.16, Q=1.76), ellipsoid to cylindrical, occasionally broadly ellipsoid or even subglobose, hyaline, thin walled, with few contents. Basidia (Fig. 2b) 18–24×5–7 μm, clavate, bearing 4 sterigmata. Cheilocystidia (Fig. 3d) 19–35×4–6.5 μm, narrowly clavate, to utriform, hyaline, thin-walled with some contents. Sclerocystidia (Fig. 2c) scattered, 37–52×10–16 μm, with a thickened, hyaline or pale brown wall up to 3 μm thick. Hairs on the pileus (Fig. 2e) dense, 8–10 μm in diameter, with a thickened pale brown wall up to 4 μm thick. Clamp connections are prominent in generative hyphae.
Habitat: On dead wood, in clusters, in rainforest dominated by Castanopsis armata, Dipterocarpus sp., Ficus sp. And Tabebuia chrysantha.
Specimen examined: THAILAND, Chiang Rai Province., Thasud, Muang Dist., Mae Fah Luang University Park, 18°05′59.1″N, 102°40′02.9″E, elevation 488 m., dominated by Dipterocarpus sp., Ficus sp., and Tabebuia chrysantha. 18 June 2009, BJP 021 (MFLU10 0151) Distribution Only known from northern Thailand.
Notes:This new species is characterized by its small, grayish orange basidiomes and very large, 37–52 × 10–16 μm, scattered, clavate sclerocystidia with a broadly rounded apex. In some aspects Lentinus megacystidiatus bears superficial resemblance to L. strigosus (Schwein.) Fr. but L. strigosus differs in having pallid ochraceous to brownish basidiomes and cylindric, subclavate or sub-ventricose metuloids with an obtusely rounded apex (Corner 1981; Pegler 1983). Lentinus megacystidiatus also bears superficial resemblance to L. torulosus (Pers.: Fr.) Lloyd, which has very large, clavate cheilocystidia, 24–60 × 7–16 μm, whereas L. megacystidiatus has moderate sized (19–35 × 4–6.5 μm), narrowly clavate, cheilocystidia (Corner 1981; Pegler 1983). Lentinus megacystidiatus forms clusters of basidiomes on dead and decaying wood. (Notes from Karunarathna et al. 2011)
Fig. 1 Maximum parsimony phylogram showing phylogenetic relationships among two new Lentinus species L. concentricus (MFLU08 1375) and L. megacystidiatus (MFLU08 1388) with some selected Lentinus sensu stricto and Polyporus species based on ITS sequences. Data were analyzed with random addition sequence, unweighted parsimony and gaps were treated as missing data. Values above the branches are parsimony boostrap (≥50%).The tree is rooted with Pleurotus ostreatus (EU520193). (Phylogenetic tree from Karunarathna et al. 2011)
Fig. 2 c,d basidiomes of Lentinus megacystidiatus (MFLU08 1388). Scale bars (c,d) 30 mm
Fig. 3 Lentinus megacystidiatus (MFLU08 1388). a Spores, b basidia, c sclerocystidia, d cheilocystidia, e hairs on the pileus, f skeletal hyphae, g generative hyphae. Scale bars (a–d) 20 μm, (e–g) 10 μm.
Karunarathna SC, Yang ZL, Zhao RL, Vellinga EC, Bahkali AH, Chukeatirote E and Hyde KD 2011– Three new species of Lentinus from northern Thailand. Mycological progress, 10(4), pp.389-398.