Fulvifomes karaiensis M. Kaliyaperumal, S. Gunaseelan & K. Kezo sp. nov.

Index Fungorum number: IF 559691;  MycoBank number: MB 559691; Facesoffungi number: FoF 12670; Fig. 1

Etymology – The species epithet “karaiensis” referring to the region of basidiomata collected

Macromorphology – Basidiocarp perennial, solitary, pileate, sessile, light in weight, hard when dry. Pileus applanate, triquetrous, projecting up to 6.1 cm, 11.5 cm wide and 5.8 cm thick near the attachment. Pilear surface meagrely warted near margin, weakly zonate, brown (6E5), on maturity pilei becoming rough, with few cracks, brownish grey (6F8). Margin entire, obtuse, velutinate, yellowish brown (5E8). Pore surface yellowish brown (5E7). Pores regular, round to angular, 4–5 per mm. Dissepiments entire, thick. Context up to 1 cm near the margin and up to 5 cm near the attachment, homogeneous, golden brown (5D7). Tubes brown (6E6), tubes layers not stratified, up to 1.1 cm.

Micromorphology – Hyphal system strictly dimitic, Generative hyphae dominant, both generative and skeletal hyphae acyanophilous, tissue darkening with KOH without swelling. Context generative hyphae, thin to thick-walled, hyaline to yellow, frequently simple septate, branched, 2–5.2 μm diameter; skeletal hyphae, thick-walled with narrow lumen, yellowish brown, aseptate, unbranched, 2–5 μm diameter. Trama generative hyphae, thin to thick walled, yellow to brown, infrequently septate, rarely branched, 2–5 μm diameter; skeletal hyphae, thick-walled with narrow to wide lumen, yellowish brown, aseptate, unbranched, 2–5.2 μm diameter. Setae absent. Cystidioles hyaline, ventricose to fusoid with elongated apical portion, 8.1–22.1×2.6–4.2 µm. Basidioles dominant, clavate, 6.5–14×2.6–6.9 µm. Basidia clavate to broadly clavate, with four sterigmata, 6.5–15.2×2.6–7.2 µm. Basidiospores globose to subglobose, thick–walled, smooth, golden yellow in water, turning rust brown in KOH, (5.2–)5.5–6 (– 6.2)×(4.7–) 5.2–5.5 (– 5.7) µm, Q=1.07 (Q range 1–1.15) (n=50/2), CB ̄, IKI ̄.
Material examined: India, Tamil Nadu, Sivagangai District, Karaikudi, 10º04′ 45″ N 78º47′ 71″ E, on Peltophorum pterocarpum, 9 Febraury 2018, Malarvizhi Kaliyaperumal (MUBL4016, holotype; CRKK2/2A, isotype).

GenBank numbers – ITS: ON333609, OP028976; LSU: ON326580, OP028972.

Notes – Our collection (MUBL4016) shares similarity with Fulvifomes azonatus, F. jouzaii, F. nakasoneae (Wu et al. 2022), F. nonggangensis, F. tubogeneratus (Zheng et al. 2021), F. thailandicus (Zhou 2015), F. submerrillii (Liu et al. 2020) and F. yoroui (Olou et al. 2019) by having dimitic hyphal system and cystidioles alone. However, our collection shows significantly different, distinct morphological characters viz., numbers of pores/mm, size and shape of basidiospores with other Fulvifomes having dimitic hyphal system and cystidioles.

Figure 1 – Fulvifomes karaiensis (MUBL4016, halotype). a, b Basidiocarp. c Pore surface. d CS of basidiomata (d1. Context. d2. Tube layer.). e Cystidiole. f Basidioles. g Basidia. h Basidiospores in KOH. i Basidiospores in cotton blue. j Basidiospores in melzer’s reagent. k Contextual hyphae. l Tramal hyphae. m Cystidioles. n Basidioles. o Basidia. p Basidiospores. Scale bars: a, b=5 cm, c=1 mm, d=1 cm, e–p=5 µm