Porotheleum microsporum P. M. Wang, Z. B. Huang, Y. Q. Wei & J. X. Shen, 2024

Wang, Pan-Meng, Li, Zhuang, Wei, Yong-Qi, Huang, Zhi-Bo, Tian, Wen-Jie, Shen, Jing-Xu, Han, Dong-Fang & Shao, Xiao-Na, 2024, A new agaricoid species of Porotheleum (Porotheleaceae, Agaricales) from Shandong Province, China, Phytotaxa 670 (1), pp. 55-62 : 58-60

Porotheleum microsporum P. M. Wang, Z. B. Huang, Y. Q. Wei & J. X. Shen , sp. nov. ( Fig. 2 )

MycoBank no.: MB 853453

Etymology:—the epithet, microsporum , refers to the small basidiospores compared to those of the other Porotheleum species described so far.

Type:— CHINA. Shandong Province: Ji’nan City, Quancheng Park , on the trunk of Salix babylonica L., elev. 47 m, 4 September 2023, P. M. Wang 219A (EFHAAU10566, holotype!). [GenBank accession numbers—ITS: PP576323, LSU: PP576335 ; all from holotype] .

Description:—Basidiomata ( Fig. 2a ) on the trunk of Salix babylonica . Pileus small, omphalinoid, (3) 5–20 (2.5) mm diam., convex to applanate at first, then planoconvex with the centre depressed; surface smooth, greasy; center pale ochre-yellow (5A3–5C3), elsewhere yellowish (5A1–5A2), or pale-yellow (4A1–4A2), subviscid to viscid when wet; transparently sulcate when moist, slightly translucently furrowed to the centre, involute. Lamellae cream to yellowish white (2A2); edge even, thick, distant, at the bottom slightly intervenose, decurrent, with interspersed lamellulae of various lengths.

Stipe central, (2) 5–18 (29) × 0.5–2 (2.5) mm, cylindrical to tapering upwards, near lamellae pale-yellow (5A2), basal part reddish-brown (5E2) to dull dark (red-) brown (5E6); surface not viscid. Context thin, whitish to pale-yellow (4A1–4A2). Odour non-distinctive, taste mild.

Basidiospores ( Fig. 2b ) [82/10/4] (4.4) 4.8–7.4 (7.75) × (2.6) 3.0–4.5 (4.8) μm (X = 6.1 ± 0.80 × 4 ± 0.47 μm), Q = (1.23) 1.33–1.85 (1.93), (Q m = 1.53 ± 0.15), ellipsoid, smooth, thin-walled, hyaline, cyanophilic, congophilic, nonamyloid. Basidia ( Fig. 2d ) 16–40 × 4.5–7 μm, narrowly clavate, thin-walled, 2-spored, long claviform, sterigmata up to 6 μm long. Hymenial cystidia absent. Hymenophoral trama composed of colourless, thin-walled cylindrical filamentous hyphae, 3–10.5 μm wide. Pileipellis ( Fig. 2c ), a cutis composed of wide hyphae, 3.5–7.5 (9) μm wide., slightly thick-walled, subcylindrical to fusiform, brownish, brown to yellow tawny, pileocystidia absent. Subcutis consists of colourless, thin-walled, subcylindrical to fusiform, 6–13.5 μm wide, with scattered small crystals. Stipitipellis ( Fig. 2e ) a trichoderm composed of caulocystidia and hyphidia; caulocystidia ( Fig. 2f ) narrowly lageniform, narrowly fusiform or narrowly conical, fusoid-lanceolate, yellow-brown, thick-walled, 10–40 × 4–8 μm; hyphidia abundant, thin-walled, unbranched, 2–5 μm wide. Clamp connections present in all parts of basidiomata.

Habitat (Ecology):—Ecology saprobic; growing alone or gregariously on the trunks of Salix babylonica distributed in Quancheng Park (Ji’nan City, Shangdong Province, China) at an elevation of 47m.

Distribution:—currently known only from Quancheng Park in Ji’nan City.

Additional specimens examined: CHINA. Shandong Province: Ji’nan City, Quancheng Park, on the trunk of Salix babylonica , elev. 47 m, 4 September 2022, P. M. Wang 219B (EFHAAU10567! [ GenBank accession numbers—ITS: PP576324, LSU: PP576336 ]; same location, 4 September 2022, P. M. Wang 219C (EFHAAU10568!) and P. M. Wang 219D (EFHAAU10569!).

Remarks:—It differs from the other similar species by its small-sized basidiomata on the trunk of Salix babylonica , yellowish pileus with a center pale ochre-yellow, and relatively small basidiospores.

Figures

FIGURE 2. Basidiomata and microstructures of Porotheleum microsporum (holotype, EFHAAU2894). a Basidiomata; b Basidiospores, bar = 5 μm; c Elements of pileipellis, bar = 10 μm; d Basidia, bar = 10 μm; e Elements of stipitipellis, bar = 10 μm; f Caulocystidia, bar = 10 μm.