Termitomyces assamicus L.R. Das, Narzary, A.K. Dutta, 2023

Das, Lakshmi Rupa, Chattopadhyay, Pinaki, Dutta, Arun Kumar, Narzary, Diganta & Rana, Tikam S., 2023, Termitomyces assamicus (Lyophyllaceae) - A new species of Termitomyces from India, Phytotaxa 599 (2), pp. 126-136 : 129-131

Termitomyces assamicus L.R. Das, Narzary, A.K. Dutta , sp. nov. Figs. 1 & 2

MycoBank MB 848233

Etymology:—The specific epithet “ assamicus ” refers to the locality (Assam State) from where the type specimen was collected for the first time.

Diagnosis:—Differs from T. clypeatus by having a pileus coloured brownish orange to grey or greyish red, a non-spiniform perforatorium coloured brownish orange to grey or brownish grey to greyish brown, a serrated lamellae edge, a stipe coloured orange grey to greyish orange or cream, a smaller pseudorhiza (70–100 mm long), somewhat larger basidiospores (mean 8.3 × 5.0 μm vs. 6.2 × 3.6 μm in T. clypeatus ) shaped ellipsoid, and less broad cheilocystidia (21–36 × 8–16 µm vs. 18–38 × 11–25 μm in T. clypeatus ) shaped clavate.

Holotype:— INDIA. Assam: Sonitpur District, Tezpur, Ketekibari , 26°38’51.7”N, 92°46’36.6”E, elev. 74.0 m, 25 June 2021, L. R. Das, TMC 92/2021 ( GUBH20038 ).

Description:— Pileus 30–76 mm diam., initially conical to campanulate, becoming cuspidate to convex or broadly convex with a conical, pointed perforatorium, not scrobiculate, margin incurved at early stages, later uplifted and frequently rimose, surface brownish orange (5C4) to grey (5B1, 7B1) or greyish red (7B3) with perforatorium coloured brownish orange (5C3) to grey (6D1) or brownish grey (6D2) to greyish brown (7E3), silky fibrillose, often radially striate; context 2–8 mm thick at the center, white. Partial veil absent. Lamellae 2–8 mm broad, free, initially white to pale grey (1B1), becoming pinkish with age, crowded with 1–2 series of lamellulae, margin serrated, concolorous. Stipe 50–100 × 4–6 mm, central, subcylindrical with some specimens showing a slight thickening at the base before tapering to form an underground pseudorhiza, surface orange grey (5B2) to greyish orange (5B3) or cream, fibrillose; context white, solid. Annulus absent. Pseudorhiza 70–100 mm long, cylindrical, surface greyish brown (5D3) to yellowish brown (5E4), radially fibrillose; context white to cream, solid. Odour mushroomy. Taste not recorded.

Basidiospores (6.8–)7.5–9.5(–11.3) × (3.5–)4.5–5.3(–7.5) µm [X m = 8.3 ± 1.2 × 5.0 ± 0.8 μm, Q = 1.4–1.9, Q m = 1.7 ± 0.2, n = 30, s = 2 specimens], ellipsoid, 1–2 guttate, thin-walled. Basidia 20–26 × 6–11 μm, clavate, hyaline, thin-walled, 4-spored. Basidioles 16–20 × 8–11 µm, clavate, hyaline, thin-walled. Cheilocystidia 21–36 × 8–16 µm, clavate, granules present, thin-walled. Pleurocystidia 23–32 × 12–23 µm, broadly clavate to pyriform, hyaline with KOH, thin-walled. Pileipellis a cutis, hyphae 14–50 × 5–9 µm cylindrical, sometimes branched, pale grey with KOH, thin-walled. Lamellae trama hyphae 5–10 µm broad, pale grey with KOH, thin-walled. Stipitipellis hyphae 2–4 µm broad, pale grey with KOH, regular, thin-walled.

Ecology and distribution:—Terrestrial; solitary, scattered or in a group, on moist soil in association with termite nests. Known only from Assam, North East India.

Additional specimens examined:— INDIA. Assam: Sonitpur District, Tezpur, Ketekibari , 26°38’51.8”N, 92°46’36.4”E, elev. 74.0 m, 06 July 2021, L. R. Das, TMC 94/2021 (GUBH20039).

Molecular analyses

The ITS-rDNA dataset was used to estimate the phylogenetic relationships between the chosen species ( Fig. 3 ). There were 41 sequences and 703 characters in the alignment, with 456 unique alignment patterns and 21.20 percent gap. In the alignment, pair-wise substitution rates recorded were: AC = 1.226837, AG = 2.511242, AT = 1.268418, CG = 0.751539, CT = 3.048358, GT = 1.000000; while the base frequencies of A, C, G, and T were 0.214423, 0.229144, 0.227104, and 0.329329, respectively. Alpha, the shape parameter of the gamma distribution, was equal to 0.707354, and the tree length was 1.714454.

Only the best ML tree with an optimization likelihood value of -4523.132735 is shown ( Fig. 3 ), and support values recovered from ML (MLBS 50%) and BA (PP 0.50) are reported. The phylogenetic tree that was recovered from the RAxML and the Bayesian analyses showed that they were almost identical in topology.

Pairwise comparisons of aligned, overlapping ITS-rDNA sequences of the newly described taxon, T. assamicus (GenBank accession no. OQ346313 and OQ976999), with the top ten BLAST results indicate highest similarity with two earlier deposited sequences from India [GenBank MK743976 (99.8% similarity; query coverage 99%) and MK743955 (99.6% similarity; query coverage 99%] both of which were named after T. medius voucher BUMR07 and T. entolomoides voucher BUMR06, respectively. A similar result was also observed in the phylogenetic analysis ( Fig. 3 ), where, T. assamicus clustered with both the sequences of T. medius and T. entolomoides with strong support values (100% BS, 1.00 PP). Termitomyces assamicus is resolved sister to a cluster containing the taxa like T. clypeatus and T. intermedius .

Figures

FIGURE 1. Termitomyces assamicus (GUBH GUBH20038, holotype, photos by L. R. Das): A-B. Fruit bodies in natural habitat; C. Mature fruitbody showing upturned and rimose pileus margin; D. Basidioma showing pseudorrhiza. Scale bars:A–D = 10 mm.

FIGURE 2. Microscopic features of Termitomyces assamicus (GUBH20038, holotype): A. Basidiospores; B. Basidia; C. Basidioles; D. Cheilocystidia; E. Pleurocystidia; F. Hyphal cells in the pileipellis. Scale bars: A–F = 10 μm.

FIGURE 3. Using the GTR+G model of nucleotide evolution, a tree with the highest likelihood (-InL = 4523.132735) was constructed. Values to the left of “/” show support for the MLBS, while values to the right of “/” show support for the Bayesian posterior probabilities (PP). MLBS values less than 50% and PP values less than 0.5 are not shown here. Type sequences are in bold, and the sequence in blue bold is from the present study.After each taxon name, the GenBank accession number and country of origin are given.