Termitomyces intermedius Har. Takah. & Taneyama
Mycobank number: 809940
Basidiomata medium-sized. Pileus 4–11 cm in diam., broadly conical or convex when seen from aside, dark grey (1F1), unchanging, often rimose-squamulose in dry condition, squamules easily falling away; margin deflexed to inflexed, undate; perforatorium small and mucronate, dark grey (1F1); context white (1A1), 2–3 mm thick half-way to the margin, tough. Lamellae subventricose, 5–7 mm wide, subfree, crowded, white (1A1) when young, becoming to yellowish white (1A2) when mature; lamellulae in 1–2 tiers; lamellar edge eroded. Stipe central, 3–13 × 1.2–1.6 cm, cylindrical, sometime subbulbous (1.9–2.3 cm) at the base, pale grey (1B1) usually rimose in dry condition, smooth, sometimes irregularly pustulate bumps on the surface; context solid, white, fibrous. Annulus absent. Pseudorhiza terete, tapering downwards; surface pale grey (1B1), smooth; context solid, fibrous. Odour pleasant. Taste not distinctive.
Basidia 43–68 × 10–20 μm, av. 50 ± 8.3 × 14 ± 2.5 μm, clavate, thin-walled, 1-spored or 2-spored, (4-spored basidia not seen); sterigmata 1–2 μm long. Basidiospores [67/9/3] (9.0–) 10.3–14.1 (–14.9) × (5.3–) 5.8–8.9 (–10.2) μm, Lm × Wm = 11.9 ± 1.1 × 7.3 ± 0.9 μm, Q = 1.4–1.8 (–2.0), Qm = 1.60 ± 0.18, broadly ellipsoid to ellipsoid, colorless, thin-walled, smooth. Hymenophoral trama regular, parallel, 150–230 μm wide, made up of thin-walled, fusiform to narrowly cylindrical hyphae elements 10–23 μm wide, filamentous hyphae abundant, 4–6 μm wide. Subhymenium 8–15 μm thick, with 1–2 layers of ovoid, subglobose, fusiform, ellipsoid or irregular cells, 5–7 × 3–5 μm. Pleurocystidia 40–136 (–169) × 19–34 μm, av. 95 ± 34.1 × 24 ± 9.9 μm, oblong, obovoid or ellipsoid, thin-walled. Lamellar edge heteromorphous, with abundant cheilocystidia. Cheilocystidia 52–114 × 20–29 μm, av. 78 ± 23.3 × 29 ± 8.4 μm, clavate to pyriform, narrowly lageniform, lageniform or broadly lageniform, thin-walled. Pileipellis 2-layered; suprapellis an ixocutis composed of cylindrical hyphae with obtuse apex, thin-walled, hyaline at places in KOH and terminal elements 16–73 × 3–6 μm, av. 46 ± 17.3 × 5 ± 0.9 μm; subpellis made up of inflated elements, 52–131 × 20–27 μm, av. 95 ± 24.8 × 24 ± 8.4 μm. Clamp connections not seen in any tissue.
Habitat and distribution: Basidiomata scattered to gregarious around termite underground nests; occurring in summer. Known from China and Japan.
Additional material examined: China. Yunnan Provinces: Kunming city, Shilin county, altitude 1,750 m, 12 July 2019, S.M. Tang 2019071204 (HKAS 117639); Baoshan city, Kejie village, altitude 1,680 m, 3 August 2019, Song-Ming Tang 2019080315 (HKAS 117640); Kejie village, altitude 1,599 m, 3 August 2020, Feng-Ming Yu 2019080321 (HKAS 117641); Dali city, altitude 1,890 m, 21 July 2020, Jun He 202072101 (HKAS 117643); Yuxi city, 1,708 m, 24 July 2020, Jun He 2020072422 (HKAS 117644).
Notes: Termitomyces intermedius was originally described from Japan (Terashima et al. 2016), subsequently, it was reported from China in Guangdong province (Huang et al. 2017). Comparison of our specimen (HKAS117638) with T. intermedius (TNS-F-48178, Terashima et al. 2016) ITS sequences showed 0.65% difference (4/614 differences, including 3 gaps); nrLSU 100% similarity with GDGM46311 and GDGM46325 (Huang et al. 2017); tef1 100% similarity with FB-T1-04 (Kobayashi et al. 2021). Morphologically, our specimen HKAS117638 has narrowly lageniform, lageniform or broadly lageniform cheilocystidia, pileus and stipe surface often rimose-squamulose in dry condition, squamules easily falling away, stipe surface pale grey and sometime subbulbous at the base, while the original description mentioned that T. intermedius has broadly clavate to pyriform cheilocystidia and did not mention the pileus and stipe surface in dry condition, stipe white on the surface and cylindrical (Terashima et al. 2016). In Termitomyces species, cheilocystidia shape can be variable within the same species. In T. aurantiacus (R. Heim) R. Heim for example, cheilocystidia can be rostrate, with median constriction, or moniliform. In T. mammiformis R. Heim cheilocystidia can be ovoid, with a median constriction, or narrowly utriform. In T. schimperi cheilocystidia can be rostrate, oblong, narrowly utriform, or conical.
Fig. 1 Strict consensus tree illustrating the phylogeny based on the combined nrLSU, mrSSU, 5.8S and ITS1+ITS2 data set. Maximum likelihood bootstrap proportions equal to or higher than 70%, and Bayesian posterior probabilities equal to or higher than 0.90 are indicated at nodes. The two Asterophora species and two Lyophyllum species were used as the outgroup. The two newly described species are in red. Holotype specimens are in bold.