Pleurotus giganteus (Berk.) Karunarathna and K.D. Hyde (2011:62)

Dasanthi, Naduni, Thambugala, Kasun M., Karunarathna, Samantha C., Ediriweera, Aseni, Munasinghe, Helani, Elgorban, Abdallah M., Harischandra, Hiruni & Dharmasena, Buddhika P., 2024, Morphological and molecular insights into the hidden edible mushroom diversity in Sri Lanka, Phytotaxa 645 (3), pp. 192-213 : 197-198

Pleurotus giganteus (Berk.) Karunarathna and K.D. Hyde (2011:62)

Index Fungorum: 561087

Figure 4 and Figure 5

Basidiomata large, pileus 100–110 mm in diameter, infudibuliform when young, turns to applanate with eye brown (7F6) central depression, champagne (4B4), orange white (6A2) to greyish orange (5B4) towards the margin, center densely scaly, covered with innately disrupted indefinite, small hair brown (5E4) or dark brown (6F5) squammules, fades with maturity to pale ochraceous, yellow or yellowish brown (E8), occasionally dry, margin thin, strongly involute, straight at maturity, slightly sulcate-striate. Lamellae decurrent, moderately crowded, lamellulae formed with five lengths, slightly interveined and linked over the top stipe, 2–4 mm broad, white to cream (3A2); edge entire, pale ochraceous or yellowish brown (E8). Stipe 80–100 mm long, 8–10 mm broad closer to the apex, 10–14 mm at the base, fusiform, solid, stipe surface rough, dark brown (6F6), paler at the apex, tomentose, scaly, with indefinite zones of paler velar remnants when young. Context white in both pileus and stipe, fleshy, composed of dimitic hyphal system. Generative hyphae 3.8–6 μm in diameter, slightly thickened wall, frequently branching, clamp connections present, skeletal hyphae 5.8–8.1 μm in diameter, thick-walled with a narrow lumen.

Basidiospores 6.7–9.6 × 6–7 μm (Qm= 1.3), ellipsoid, broadly ellipsoid or oblong ellipsoid, white, smooth, thin-walled, inamyloid, with one large oil drop or occasionally multiguttulate, thin-walled. Basidia 23–38 × 8.2–9 μm, clavate, elongate, 4 sterigmated. Lamella edge sterile, Cheilocystidia abundant, 14–27 × 5.4–10 μm, lecythiform, ventricose base, hyaline, thin-walled.

Ecology and distribution:— It grows solitarily on soil with decaying leaf litter and woody debris. Termitomyces heimii is widely distributed in Australia, China, the Malay Peninsula, Sabah, Sri Lanka, Thailand, and Vietnam.

Material examined:— Sri Lanka. Sabaragamuwa Province: Rathnapura District, Balangoda, 80°45’12.07”E 6°40’55.36”N, 7 th August 2022, Naduni Dasanthi, GenBank accession number: OR139842, Specimen number: RH10 (USJ-GMBU-002).

Phylogenetic analyses of Pleurotus

A total of 52 sequences of Pleurotus species were included in the phylogenetic analyses. Hohenbuehelia mastrucata and H. auriscalpium were chosen as the outgroup taxa for the phylogenetic tree. The sequence obtained from the specimen RH10 (USJ-GMBU-002) clustered with P. giganteus , forming a monophyletic clade ( Figure 6 ). The collected P. giganteus ( RH 10) exists as a sister taxon to the subclade in clade B containing P. giganteus with GenBank accession numbers KP135560, KP012913, and KP120920 (from Thailand, Australia, and Sri Lanka, respectively) with a strong bootstrap support (100%). In the phylogenetic tree, P. giganteus KP 120920 ( MFLU 10-0141 voucher) is the epitype from Sri Lanka, which is present as a sister taxon to the P. giganteus KP 135560 ( MFLU 14-0638 voucher) from Thailand indicating that they are more closely related.

Notes:— Pleurotus giganteus was originally described as Lentinus giganteus in Sri Lanka ( Berkeley 1847). Karunarathna et al. (2011) used ITS rDNA sequence data and morphological features to move the taxonomic position of Lentinus giganteus Berk. to Pleurotus giganteus based on Thai and Sri Lankan collections resolving the taxonomy. Apart from Sri Lanka and Thailand, it has been recorded in Malaysia, China, Laos, Vietnam, Australasia, Papua New Guinea, and Indonesia ( Phan et al. 2019).

The nutrient composition of P.giganteus has revealed that it typically contains high levels of protein, carbohydrates, and minerals while having a low-fat content ( Thachunglura 2023). It is a wild edible mushroom consumed by communities in tropical and subtropical regions such as China, Malaysia, Indonesia, Thailand, and Sri Lanka and has gained attention for its potential as a commercially cultivatable mushroom ( Phan et al. 2019). However, it has not yet been cultivated as a commercial mushroom in Sri Lanka.

Figures

FIGURE 4. Pleurotus giganteus (Herbarium code: USJ-GMBU-002) a, b. Mature basidiomata in situ. Scale bars = 2.5 cm. Photography by Naduni Dasanthi.

FIGURE 5. Pleurotus giganteus (Herbarium code: USJ-GMBU-002) a. Spores. b. Basidia. c. Cheilocystidia. d. Generative hyphae. e. Skeletal hyphae. Scale bars: a = 5 µm; b,c = 20 µm; d, e = 10 µm. Illustration by Aseni Ediriweera.

FIGURE 6. A phylogenetic tree for ITS sequences was constructed using maximum likelihood (ML) analysis for the genus Pleurotus. The newly generated strain is in red. ML bootstrap values are given at the nodes. Bootstrap support values equal to or higher than 70% are provided. The tree is rooted with Hohenbuehelia mastrucata and H. auriscalpium.