Phlebiopsis subgriseofuscescens K. Kezo, M. Kaliyaperumal & S. Gunaseelan sp. nov.
Index Fungorum number: IF 902415; Mycobank number: MB 902415; Facesoffungi number: FoF 13989; Fig. 1
Etymology – The species epithet “subgriseofuscescens”, signifies the close relation with the species Phlebiopsis griseofuscescens.
Holotype – MUBL4024
Description – Basidiomata annual, resupinate to effuse reflexed, subceraceous when fresh, turning leathery on drying, up to 20 cm long, 7 cm wide, 3 mm thick. Pilei laterally fused, pileal surface tomentose, white (5A1) when fresh turning orange white (5A2) on drying. Context duplex, greyish orange (5B3) towards tomentum and greyish drown (7D3) towards tube, up to 1 mm in thickness. Hymenial surface brownish violet (11D7) when fresh turning greyish brown (7D3) on drying. Pores hydnoid, projecting up to 1 mm, and angular pores towards margin, 1–2 per mm. Margin white (5A1) when fresh becoming creamy to orange white (5A2) on drying.
Hyphal system monomitic; context generative hyphae, thin to thick walled, hyaline, simple-septate, branched, 2.5–5 μm dia., CB ̄, IKI ̄. Trama generative hyphae, thin to thick walled, hyaline, simple-septate, branched, 2.5–6 μm dia., CB ̄, IKI ̄. Cystidia clavate, thick-walled, coarsely encrusted, projecting above the hymenium, 48–83×6–7.2 μm. Cystidioles absent. Basidioles narrowly clavate, 14–20 × 3.5–5.5 μm. Basidia narrowly clavate, with a simple septum at the base and four sterigmata, 16–24.2×3.5–6.2 μm. Basidiospores smooth, hyaline, thin-walled, allantoid to cylindrical, (6–)6.5–7.1(–7.5)×(2.2–)2 .4–2.6(–3.1) μm (n=30/2), Q=2.7; CB ̄, IKI ̄.
Materials examined – India, Tamil Nadu, Thiruvannamalai District, 12° 29′ 14.4″ N 78° 55′ 06.0″ E on dead angiosperm wood, 14th Nov. 2019, Kezhocuyi Kezo (MUBL4024, holotype).
Additional materials examined – India, Tamil Nadu, Salem District, 11° 47′ 40.1″ N 78° 12′ 44.9″ E, on dead angiosperm wood, 23rd Jan. 2018, Kezhocuyi Kezo (Isotype KSM-HRS31), same collection site (Isotype KSM-HRS30, KSM-HRS9). India, Tamil Nadu, Thiruvannamalai district, 12° 29′ 13.5″ N 78° 55′ 07.0″ E on dead angiosperm wood, 27th Mar. 2018, Kezhocuyi Kezo (Isotype KSM-PK6). INDIA, Tamil Nadu, Trichy District, 11° 17′ 21.4″ N 78° 36′ 12.3″ E on dead angiosperm wood, 14th Feb. 2018, Kezhocuyi Kezo (Isotype KSM-KK15).
GenBank numbers – MUBL4024; ITS: OP101632; LSU: OP379562, KSM-HRS31; ITS: OP101633, KSM-KK15; ITS: OP379520
Notes – Phlebiopsis subgriseofuscescens is characterised by their resupinate to effuse reflexed basidiocarp, brownish violet, hydnoid hymenophore and cylindrical spore. Our Indian species shares similar characters with P. griseofuscescens except for the spore size, as the latter has smaller ellipsoid spores ((4–5.5)–6×2.5– (3–3.5) μm) (Xu et al. 2020; Chen et al. 2021; Zhao et al. 2021). Phlebiopsis dregeana differs from our Indian species having smooth to glabrous hymenophore and larger ellipsoid spores (6.5–8×4–5 μm) (Hjortstam and Ryvarden 1990; Zhao et al. 2021). Our observations on morpho-microscopic illustrations are consistent with phylogenetic analyses. ML and Bayesian analyses inferred from combined dataset of ITS and nLSU of Phlebiopsis spp. revealed that our Indian species formed a new lineage to P. griseofuscescens (0.99 BYPP /100% ML) and P. dregeana (1 BYPP/100% ML) clade. Our strain shows variation in hymenophore and basidiospore size
and shape with P. cylindrospora (smooth hymenophore and
cylindrical spore ((5–)5.5–7.5(–8)×1.8–2.8 (–3)).
Figure 1 – Phlebiopsis subgriseofuscescens (MUBL4024, holotype) Microscopic structures of Phlebiopsis subgriseofuscescens (drawn from the holotype). a Basidiomata. b1 Duplex context. b2 Tube layer. c Encrusted cystidia. d Encrusted cystidia and basidia. e Thin and thick-walled generative hyphae. f Encrusted cystidia. g
Basidioles. h Basidiospores. i Basidiospores phloxine. j Water. k Cotton blue. l Melzer. Scale bars: b=1 mm, c–l=10 μm