Lentinus concentricus Karun., K.D. Hyde & Zhu L. Yang
Index Fungorum number: 518249; MycoBank: 518249
Pileus (Fig.1) 6.5–7 cm in diameter, thin, with deeply umbilicate centre, when seen from above circular, yellowish brown-clay (5D5) at margin, yellowish brown (5E8) towards centre, surface from centre to margin velvety, soft, concentrically zonate, with brownish grey (6F8) hairs at margin; hairs grayish orange (5B4) towards centre. Lamellae deeply decurrent, 0.5 mm broad, with 5 tiers of lamellulae, pompeian yellow (5C6) when young and old, with entire edge. Stipe 4–4.5×5–6 mm, cylindric, solid, leathery, dry, yellowish brown-clay (5D5) when young, raw umber (5F8) when old, surface velvety/velutinous, short/soft hairs; brownish grey color (6F8); with white context up to 2 mm thick at the disk, consisting of a dimitic hyphal systems with skeletal hyphae (Fig. 2d). Generative hyphae (Fig. 2d) 3–4 μm diameter, not inflated, hyaline, thin-walled, frequently branched, with clamp connections. Skeletal hyphae 3–4.5 μm diameter, sinuous, cylindric, hyaline, with a thickened wall and narrow lumen, unbranched. Diameter of hairs on the surface of pileus 5–5.5 μm. Basidiospores (Fig. 2a) 5–7×2.5–4 μm (n=20, Lm=6.78 μm, Wm=3.75 μm, Q=1.5–2.4, Q=1.8) ellipsoid to cylindrical, occasionally broadly ellipsoid or even subglobose, hyaline, thin-walled, with few contents. Basidia (Fig. 2c) 19–25×5–6.5 μm, clavate, bearing 4 sterigmata. Lamella edge sterile with crowded cheilocystidia. Cheilocystidia (Fig. 2b) 20–30×5–7 μm, narrowly clavate, some with apical excrescence (10–12 μm long) hyaline, thin-walled. Sclerocystidia absent. Hairs on the pileus (Fig. 2e) dense, 5–10 μm in diameter, with a thickened pale brown wall up to 4 μm thick. (Fig. 2–3)
Holotype: THAILAND, Chiang Mai Province, Mae Taeng District, Ban Pha Deng, Mushroom Research Centre, 19° 17.123′N, 98°44.009′E, elevation 900 m, rainforest dominated by Castanopsis armata, Erythrina sp, and Dipterocarpus sp., 15 July 2008, Samantha C. Karunarathna (MFLU08 1375) Etymology concentricus, in reference to the prominent concentric zonations on the pileus surface.
Habitat: On dead wood, in cluster, in rainforest dominated by Castanopsis armata.
Distribution: Only known from northern Thailand.
Notes: This new species is characterized by its yellowish brown-clay, velvety, concentrically zonate, leathery, solid, dry and hard small basidiomes, absence of sclerocystidia and 19–25 × 5–6.5 μm, clavate basidia. The prominent zonation of the pileus is the main characteristic feature of Lentinus concentricus. In some aspects it bears superficial resemblance to Lentinus fasciatus Berk. which differs in having off-whitish to pale ochraceous basidiomes and abundant clavate or fusoid, 22–32 × 4–9 μm sclerocystidia on the sides of the lamellae (Corner 1981; Pegler 1983). Lentinus concentricus also bears a superficial resemblance to Lentinus bertieri (Fr.) Fr. and Lentinus ciliatus Lév. Lentinus bertieri differs from L. concentricus in having narrowly clavate basidia, 13.5–17 × 3.5–4.5 μm and Lentinus ciliatus also differs in having narrowly clavate basidia, 16–20 × 4–5.5 μm and 19–32 × 4–8 μm clavate to fusoid sclerocystidia (Corner 1981; Pegler 1983). (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 a Basidiomes of Lentinus concentricus (MFLU08 1375)
Fig. 3 Lentinus concentricus (MFLU08 1375). a Spores, b cheilocystidia, c basidia, d generative hyphae and skeletal hyphae, e hairs on the pileus. Scale bars (a–c) 20 μm, (d,e) 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.