Tropicoporus indicus S. Gunaseelan & M. Kaliyaperumal, 2024

Gunaseelan, Sugantha, Kezo, Kezhocuyi, Karunarathna, Samantha C., Yang, Erfu, Zhao, Changlin, Elgorban, Abdallah M., Tibpromma, Saowaluck & Kaliyaperumal, Malarvizhi, 2024, New species of Tropicoporus (Basidiomycota, Hymenochaetales, Hymenochaetaceae) from India, with a key to Afro-Asian Tropicoporus species, MycoKeys 102, pp. 29-54 : 29

Tropicoporus indicus S. Gunaseelan & M. Kaliyaperumal sp. nov.

Figs 5 , 6

Etymology.

The species epithet " indicus " (Lat.): referring to the species being collected from India.

Diagnosis.

Tropicoporus indicus is characterised by applanate to meagrely triquetrous basidiome with concentrically zonate, sulcate, glabrous, deeply cracked to rimose pilear surface, homogenous context, acute margin, mono-dimitic hyphal system, presence of cystidioles, subglobose to broadly ellipsoid basidiospores measuring 5-6 × 4.2-4.9 μm.

Type.

India, Tamil Nadu, Kallakurichi District, Kalvarayan Hills ; 11°91'30"N, 78°57'86"E; 29 Sep 2022; Sugantha Gunaseelan; on living angiosperm tree of Albizia amara ; SMK- MK2 (MUBL1083, Holotype); GenBank: OR272293 (ITS); OR272338 (nLSU) .

Description.

Basidiome perennial, pileate, woody and without distinctive odour or taste when fresh, hard when dry. Pilei applanate to meagrely triquetrous, projecting up to 5.5 cm, 7 cm wide and 4 cm thick at the base; pileal surface concentrically zonate, sulcate, glabrous, deeply cracked to rimose near attachment, dark brown (7E4), greyish-brown (7F3). Margin velutinate, 2 mm thick, acute, brown (6E7). Pore surface light brown (5D5) to yellowish-brown (5E7); pores circular, 4-6 per mm. Context homogenous, up to 0.8 cm thick, brown (6E8) to dark brown (6F8). Tubes woody hard, up to 2.5 cm long, brown (6E7); tube layers stratified, each stratum up to 0.5 cm long.

Hyphal structures.

Hyphal system monomitic in the context and dimitic in the trama, tissue darkening with KOH without swelling

Context.

Generative hyphae, thin to thick-walled, hyaline to golden yellow, simple septate, rarely branched, 2-5 μm diam.

Trama.

Generative hyphae dominant, thin to thick-walled, hyaline to pale yellow, septate, occasionally branched, 2-4.5 μm diam. Skeletal hyphae thick-walled with narrow to wide lumen, yellowish-brown, aseptate, unbranched, 2-4 μm diam.

Hymenium.

Hymenial setae dark brown, thick-walled, ventricose to subulate with sharp to blunt tips, 7-28 × 3-5 μm. Cystidia absent. Cystidioles hyaline, thin-walled, ventricose to fusoid with elongated tapering apical portion, 5-21 × 3-5 μm. Basidia clavate to broadly clavate, 7-17 × 3-6 μm, with four sterigmata and a simple septum at the base. Basidioles clavate, 5-14 × 3-5 μm. Basidiospores broadly ellipsoid to subglobose, pale yellow in water, turning golden yellow to brown in KOH, thick-walled, smooth, CB ̄, IKI ̄, (5-) 5.3-5.8 (- 6) × (4.2-) 4.7-4.9 μm (n = 50/2), Q = 1.16 (Q range 1.05-1.3).

Habitat and distribution.

Basidiomes were found on living trees of Fabaceae members ( Albizia amara and Prosopis cineraria ), distributed in Kalvarayan Hills, Kallakurichi District, Tamil Nadu, India.

Additional material examined.

India, Tamil Nadu, Kallakurichi District, Kalvarayan Hills ; 11°90'39"N, 78°55'69"E; on a living angiosperm tree ( Prosopis cineraria ); 29 Sep 2022; Kezhocuyi Kezo; SMK-MK2a (MUBL1084, Paratype); GenBank: OR272294 (ITS); OR272339 (nLSU) .

Notes.

Phylogenetically, Tropicoporus indicus was recovered in the T. linteus clade. Tropicoporus indicus is similar to T. linteus by sharing, pileate, dimidiate basidiomes, concentrically sulcate pilear surface, zonate context, smaller pores (5-7/mm), a mono-dimitic hyphal system and presence of cystidioles. While varying in the nature of cracks, T. linteus has more or less cracked basidiomes, T. indicus has irregular deep cracks in basidiomes, with larger basidiospores ( T. linteus 4.8-5.7 × 3.8-4.8 μm and T. indicus 5-6 × 4.2-4.9 μm) ( Tian et al. 2013; Wu et al. 2022). Tropicoporus indicus and T. rudis share a mono-dimitic hyphal system, but T. indicus differs from T. rudis in having zonate, sulcate, deeply cracked to rimose basidiomes and larger pores (4-6/mm). In these regards, T. rudis is characterised by fulvous, velvety, concentrically zonate, matted, rimose basidiome and smaller pores (6-7/mm) ( Wu et al. 2022). Tropicoporus indicus differs from T. angustisulcatus , T. excentrodendri , T. lineatus and T. substratificans in having mono-dimitic hyphal system and a cracked basidiome ( Zhou et al. 2015; Wu et al. 2022). Tropicoporus indicus and T. flabellatus are similar in having a mono-dimitic hyphal system, but differ significantly by having concentrical zones, sulcate, glabrous, deeply-cracked to rimose pilear surface with larger pores (4-6/mm) and broadly ellipsoid to subglobose spores (5-6 × 4.2-4.9 μm). Tropicoporus flabellatus , in contrast, has a velutinate pilear surface, uncracked basidiomes with smaller pores (7-9/mm) and smaller basidiospores (4.5-5 × 3.5-4 μm) ( Lima et al. 2022). Tropicoporus indicus and T. guanacastensis are similar in having sulcate, cracked basidiome, stratified tube, mono-dimitic hyphal system and ventricose setae. However, the former differs in larger pores (4-6/mm) and larger basidiospores ( T. indicus 5-6 × 4.2-4.9 μm vs. T. guanacastensis 4.1-5 × 3.1-4 μm) ( Zhou et al. 2015). Tropicoporus indicus and T. drechsleri share concentrically sulcate deeply-cracked pilei with mono-dimitic hyphal system, larger pores (<6/mm) and presence of cystidioles, but the South American species differs in basidiospore size (4-5.5 × 3-4.5 μm) ( Salvador-Montoya et al. 2018).

Figures

Figure 5. Tropicoporus indicus (MUBL 1083 holotype) A basidiomata (Holotype) B basidiome (SMK-MK 2 a- Isotype) C pore surface D cross-section of basidiome (arrows indicating stratified tube layers) E hymenial setae F cystidioles G-J basidiospores: G basidiospores in water H basidiospores in KOH I basidiospores in cotton blue J basidiospores in Melzer's reagent. Scale bars: 1 cm (A-D); 5 µm (E-J).

Figure 6. Tropicoporus indicus (MUBL 1083 holotype) A contextual hyphae B tramal hyphae C hymenial setae D cystidioles E basidioles F basidia G basidiospores. Scale bars: 5 µm.