Lentinus roseus Karun., K.D. Hyde & Zhu L. Yang
Index Fungorum number: 518240; MycoBank: 518240
Pileus (Fig.1) 5–5.5 cm in diameter, leathery, deeply cyathiform, when seen from above rounded flabelliform; margin eroded; surface pale yellow cream (4A3) at centre, darker towards margin and their reddish grey (11B2), not changing on bruising, dry, neither striate nor zonate. Lamellae deeply decurrent, with 5 tiers of lamellulae, 0.5 mm wide, reddish grey (11B2) close to pileus margin, pale yellow cream (4A3), towards stipe in old and young specimens, with entire edge. Stipe 1.5–2×0.5–0.7 cm, central, 1.5–2×5 mm at apex, expanding towards base 1.5–2×7 mm attached to a discoid base, solid, fusiform, yellowish white (4A2), floccose, leathery, solid, with white cottony context. Generative hyphae (Fig. 2f) 4–5 μm diameter, inflated with a slightly thickened wall, more or less radially parallel but frequently branching and with large clamp connections. Skeletal hyphae (Fig. 2e) 5–6 μm in diameter, hyaline, very thick walled with only a very narrow lumen, typically unbranched. Basidiospores (Fig. 2a) 5–7(−9) × 3–4 (−6) μm (n=40, Lm=5.93 μm, Wm=3.72 μm, Q=1.36–1.85, Q=1.59), ellipsoid to elongate, occasionally broadly ellipsoid or rarely subglobose, hyaline, thin walled, with few contents. Basidia (Fig. 2c) 18–24×5–7 μm, elongate clavate, bearing 4 sterigmata. Cheilocystidia pink pileus, large, clavate metuloids mostly with a broad rounded apex, ellipsoid to elongate basidiospores with a hyaline thin wall, a dimitic hyphal system with very thick walled unbranched skeletal hyphae. (Fig. 1–2)
Holotype: THAILAND, Chiang Mai Province, Mae Taeng District, Hot Spring National Park, Pong Duad Pa Pae, 40 kms off Chiangmai, 35 kms from the Highway Route No 1095: Mae Malai-Pai and turn right for 6.5 kms, humid montane rainforest with Quercus, Castanopsis, Lithocarpus echinops, 05 July 2008, Samantha C. Karunarathna (MFLU08 1376).
Etymology roseus: in refEtymology roseus, in reference to the rose color of the mature fruiting body.
Notes: This new species is distinguished by its relatively small basidiomes with a leathery, deeply cyathiform and pink pileus, large, clavate metuloids mostly with a broad rounded apex, ellipsoid to elongate basidiospores with a hyaline thin wall, a dimitic hyphal system with very thick walled unbranched skeletal hyphae. In many aspects, it bears superficial resemblance to Lentinus sajor-caju (Fr.) Singer. Lentinus sajor-caju (Fr.) Singer, however, has larger basidiomes with a whitish cream to mottled gray pileus, an annulate stipe and relatively narrower basidiospores. Lentinus roseus also bears superficial resemblance with L. strigosus (Schwein.) Fr. and L. torulosus (Pers.: Fr.) Lloyd. Lentinus strigosus differs from Lentinus roseus in having whitish to pallid ochraceous, more brownish basidiomes, and the pileipellis is a trichodermial epicutis, whereas L. roseus has characteristic rose basidiomes and the pileipellis is not a trichodermial epicutis. Lentinus torulosus differs from L. roseus in having narrowly clavate pleurocystidia with an obtusely rounded apex, whereas L. roseus lacks pleurocystidia (Corner 1981; Pegler 1983). Lentinus roseus forms clusters of basidiomes on dead and decaying wood. Initially, the young fruiting bodies are whitish pink, and they become pink with maturity. (notes from Karunarathna et al. 2011)
Fig. 1 a Basidiomes of Lentinus roseus (MFLU08 1376) Scale bars (b) 50 mm.
Fig. 2 Lentinus roseus (MFLU08 1376) a Basidiospores, b cheilocystidia, c basidia, d metuloids, e skeletal hyphae, f generativehyphae. Scale bars (a–d) 20 μm, (e,f) 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.