Fulvifomes thiruvannamalaiensis Gunaseelan, S., Kezo, K. and Kaliyaperumal, M., sp. nov.

MycoBank number: MB 558486; Index Fungorum: IF 558486; Facesoffungi number: FoF 10726; Fig.1

Etymology: The species epithet “thiruvannamalaiensis” refers to the type locality of collection site.

Holotype: MUBL4013

Basidiocarp perennial, solitary, sessile, applanate, broadly attached to the substrate by the narrow side, hard, woody when dry. Pileus dimidiate, convex to meagrely ungulate, lacks crust, projecting up to 4.8 cm in length, 10.4 cm in width and 3.4 cm thick near the attachment. Pilear surface partly covered with microalgae, glabrous, light brown (6D8, 6E7), rust-brown (6E8) to dark brown (6F7), finely cracked with small brownish grey scales (6E3, 6F2) concentric and radially sulcate, but coarse and deep sulci, scrupose zones near the attachment/older region, meagrely wavy near the margin. Margin entire, round to obtuse, velutinate to smooth, dark brown (6F7), brownish grey (6F2), often wavy. Pore surface yellowish raw umber brown (5F8), yellowish-brown (5E8) to brown (6E7, 6F8). Pores round, regular, 4–7 per mm. Dissepiments entire, thick. Context up to 1.6 cm, homogeneous, fibrous to corky, brown (6E7, 6F8) to dark brown (6F7). Tubes yellowish-brown (5E8), light brown (6D6) to brown (6E7, 6F8), up to 1.3 cm thick, tube layers stratified with thin-walled bright yellowish generative hyphae usually running between the old tubes, each stratum up to 0.4 cm.

Hyphal system strictly dimitic, skeletal and generative hyphae acyanophilous; tissue darkening with KOH without swelling. Context Generative hyphae dominant, thin to thick-walled, simple septate, branched, hyaline to brown, 1.2–4.8 μm diam.; skeletal hyphae, thick-walled with narrow to wide lumen, unbranched, aseptate, yellow to brown, 2.4–4.3 μm diam. Trama Generative hyphae, thin to thick-walled, septate, rarely branched, hyaline to brown, 1.2–4.8 μm diam.; skeletal hyphae, thick-walled with narrow to wide lumen, aseptate, unbranched, brown, 2.4–4.8 μm diam. Setae absent. Cystidioles thin-walled, hyaline, varies in shape, fusoid to ventricose with elongated apical portion, 12.9–27×2.8–7.2 μm. Basidioles clavate to broadly clavate, 8.5–15.5×3.5–6.5 μm. Basidia clavate to broadly clavate, with four sterigmata, 9.4–15.7×5.2–8 μm. Basidiospores broadly ellipsoid to subglobose, thick-walled, smooth, yellow in water, turning brown in KOH, (5.3–) 5.5–6.7 (–6.9)×(4.6–) 4.8–5.1(–5.5) μm (n=30/2), Q =1.05–1.3, CB ̄, IKI ̄.

Material examined – India, Tamil Nadu, Thiruvannamalai district, Jawadhu hills, Jamunamarathur, 12.64° 54′ 19.1″ N 79° 18′33″ E, on living angiosperm tree (Albizia amara, Fabaceae), 09 February 2018, Sugantha Gunaseelan, MUBL4013, holotype.

GenBank numbers – MZ221598 (ITS), MZ221600 (LSU).

Notes – Fulvifomes thiruvannamalaiensis, characterized by perennial, solitary, dimidiate, applanate to ungulate basidiomes, significantly cracked pilear surface with brownishgrey scales, stratified tube layer with dimitc hyphal system and thick-walled yellow to brown, acyanophilic subglobose to ellipsoid basidiospores. African species, F. yoroui (Olou et al. 2019) shows close resemblance with F. thiruvannamalaiensis, in sharing perennial, pileate, ungulate basidiomata, dimitic hyphal system and presence of fusoid cystidioles, but the size and shape of the basidiospores (subglobose to globose basidiospores 5.5–6.5×4.7–5.6 μm), differ from F. thirvannamalaiensis. Fulvifomes krugiodendri (Ji et al. 2017), F. rimosus (Hattori et al. 2014) and F. thailandicus (Zhou 2015) are closely similar to F. thirvannamalaiensis morphologically by sharing dimidiate, concentrically sulcate, cracked basidiocarp, dimitic hyphal system and presence of fusoid cystidioles, yet differs in the number of pores and the size of basidiospores. Despite few morphological resemblances between F. elaeodendri (Tchoumi et al. 2020) such as sulcate, glabrous pileus becoming cracked with age, stratified tube layer the distinct microscopical traits viz., absence of cystidioles and the size of the basidiospores are distinguishing F. thiruvannamalaiensis from F. elaeodendri. Fulvifomes centroamericanus (Ji et al. 2017), F. hainanensis (Zhou 2014) and F. imbricatus (Zhou 2015) besides having dimitic hyphal systems are significantly distinct from F. thiruvannamalaiensis in morphology and microscopic features, by having uncracked pilear surface, shape and size of basidiospores. Fulvifomes thiruvannamalaiensis shares a few similar morphological traits with the American species, F. cedrelae, F. robinae and F. squamosus (Salvador-Montoya et al. 2018) by having perennial, applanate, ungulate, sessile basidiomata with sulcate, cracked pilei, homogenous context and stratified tubes, however, the former differs from the later in hyphal system, number of pores and size of the basidiospore. The Chinese species F. submerrillii (Liu et al. 2020), shows high variations both morphologically and microscopically from the newly described Indian F. thiruvannamalaiensis (Fig. 2).

Figure 1 – Fulvifomesthiruvannamalaiensis (MUBL4013, holotype). a. Habitat, b. Pilear surface, c. Pore surface, d. Stratified layer (yellow arrows and lines indicates each stratum), e. Contextual hyphae, f. Tramal hyphae, g. Cystidioles, h. Basidioles, i. Basidia and j. Basidiospores (a–d= 1cm, e–j = 10µm).

Figure 2 – Phylogram of Fulvifomes species, obtained from maximum likelihood (RAxML) of combined ITS, LSU, and tef1 datasets. Bootstrap values (BS) from maximum likelihood (ML, left) and Maximum parsimony (MP, middle) greater than 70% and Bayesian posterior probabilities (PP), greater than 0.95, are indicated above the nodes as ML/MP/BYPP. The tree is rooted with Phylloporia nodostipitata FLOR 51153. New species and new records are indicated in black bold