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

Figs 7 , 8

Etymology.

The species pseudoindicus signifies the close morphological and phylogenetic relationships with the species Tropicoporus indicus .

Diagnosis.

Tropicoporus pseudoindicus is characterised by applanate to meagrely ungulate to triquetrous basidiome with broadly zonate, distinctly cracked by radial fissures, sulcate pilear surface, duplex context with black line, acute to obtuse margin, pores 6-8/mm, mono-dimitic hyphal system, presence of cystidioles, subglobose to broadly ellipsoid basidiospores measuring 4-5.2 × 3.7-4.7 μm.

Type.

India, Tamil Nadu, Kallakurichi District, Kalvarayan Hills ; 11°86'98"N, 78°55'68"E; 29 Sep. 2022; Sugantha Gunaseelan; on a living angiosperm tree ( Albizia amara ); SMK-MK4 (MUBL1087, Holotype); GenBank: OR272295 (ITS); OR272340 (nLSU) .

Description.

Basidiome perennial, pileate, woody and without distinctive odour or taste when fresh, hard and light in weight when dry. Pilei applanate, meagrely ungulate to triquetrous, dimidiate, projecting up to 5 cm, 8 cm wide and 3.5 cm thick at base; pileal surface broadly zonate, distinctly cracked by radial fissures, sulcate, brown (6E8), dark brown (7F4) to greyish-brown (6F3). Margin acute to obtuse, up to 3 mm thick, light brown (6D5). Pore surface brown (6E6) to dark brown (7E6); sterile margin brown (6E6), up to 2 mm wide; pores circular, 6-8 per mm. Context duplex with black line, woody hard, up to 1.2 cm thick, several black lines present along context, brown (6E7) to dark brown (7F6). Tubes up to 1.5 cm long, annual layers distinct, each stratum up to 0.3 cm, brown (7E8) to dark brown (6F8).

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 μm diam. Skeletal hyphae, thick-walled with narrow to wide lumen, yellowish-brown, aseptate, unbranched, 2-3.5 μm diam.

Hymenium.

Hymenial setae dark brown, thick-walled, ventricose to subulate with sharp to blunt tips, rarely with lateral appendage, 5-18 × 3-5.5 μm. Cystidia absent. Cystidioles hyaline, thin-walled, ventricose to fusoid with elongated tapering apical portion, 7-52 × 2.5-5.2 μm. Basidia clavate to broadly clavate, 7-15 × 2.7-6.2 μm, with four sterigmata and a simple septum at the base. Basidioles clavate, 5-13 × 3.5-6 μm. Basidiospores broadly ellipsoid to subglobose, pale yellow in water, turning golden yellow to brown in KOH, thick-walled, smooth, CB ̄, IKI ̄, (4-) 4.2-5 (-5.2) × (3.7-) 4-4.5 (-4.7) μm (n = 50/2) and Q = 1.14 (Q range 1.05-1.25).

Habitat and distribution.

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

Additional material examined.

India, Tamil Nadu, Kallakurichi District, Kalvarayan Hills ; 11°87'33"N, 78°42'78"E; 29 Sep 2022; Kezhocuyi Kezo; on a living angiosperm tree ( Peltophorum pterocarpum ); SMK-MK4a (MUBL1088, Paratype); GenBank: OR272296 (ITS); OR272341 (nLSU) .

Notes.

Tropicoporus pseudoindicus and T. drechsleri , share similar characteristics, such as applanate basidiomes with mono-dimitic hyphal system and the presence of cystidioles; however, T. pseudoindicus differs in having smaller pores (6-8/mm) and larger basidiospores ( T. pseudoindicus 4-5.2 × 3.7-4.7 μm vs. T. drechsleri 4-5.5 × 3-4.5 μm) ( Salvador-Montoya et al. 2018). Tropicoporus pseudoindicus resembles T. rudis in having a mono-dimitic hyphal system, presence of cystidioles, and basidiospore shape, but differs from T. rudis in having distinctly cracked, fissured to sulcate pilei, duplex context and smaller basidiospores (4-5.2 × 3.7-4.7 μm) ( Vlasák et al. 2013). Tropicoporus pseudoindicus differs from T. guanacastensis in having cystidioles and subglobose to broadly ellipsoidal spores ( T. pseudoindicus 4-5.2 × 3.7-4.7 μm vs. T. guanacastensis 4.1-5.0 × 3.1-4.0 μm) ( Tian et al. 2013). Tropicoporus pseudoindicus and T. linteus share similar pileate basidiomes with sulcate pilear surface, smaller pores (5-7/mm), mono-dimitic hyphal system and presence of cystidioles. However, the former differs in basidiospore size ( T. linteus 4.8-5.7 × 3.8-4.8 μm vs. T. pseudoindicus 4-5.2 × 3.7-4.7 μm) ( Tian et al. 2013; Wu et al. 2022). Tropicoporus pseudoindicus and T. flabellatus are similar in their mono-dimitic hyphal system, but differ significantly in pilear characteristics, absence of cystidioles and size and shape of basidiospores ( T. flabellatus 4.5-5 × 3.5-4 μm vs. T. pseudoindicus (4-) 4.2-5 (-5.2) × (3.7-) 4-4.5 (-4.7) μm) ( Lima et al. 2022). Tropicoporus pseudoindicus differs from some other reported Tropicoporus species (namely T. angustisulcatus , T. excentrodendri , T. lineatus and T. substratificans ) in having concentrically zonate, glabrous, distinctly cracked pileal surface and a mono-dimitic hyphal system ( Zhou et al. 2015; Wu et al. 2022).

Figures

Figure 7. Tropicoporus pseudoindicus (MUBL 1085 holotype) A basidiomata (Holotype) B pore surface C cross-section of basidiome (arrows indicating stratified tube layers and duplex context with black line) D hymenial setae E-H basidiospores: E basidiospores in water F basidiospores in KOH G basidiospores in cotton blue H basidiospores in Melzer's reagent. Scale bars: 1 cm (A-C); 5 µm (D-H).

Figure 8. Tropicoporus pseudoindicus (MUBL 1085 holotype) A contextual hyphae B tramal hyphae C hymenial setae D cystidioles E basidioles F basidia G basidiospores. Scale bars: 5 µm.