Termitomyces yunnanensis S.M. Tang & Raspé
MycoBank number: 845183
Basidiomata medium-sized. Pileus 4–8 cm in diam., at first convex becoming convexo-applanate to plano-concave or concave, medium grey (1E1), olive grey (1E2), light grey (1D1) to greenish grey (1D2) at center, light grey (1D1) towards margin, conspicuously venose surface; margin inflexed when young, becoming straight or reflexed when mature; perforatorium an umbo, ca. 7–9 mm, dark grey (1F1); context 2–4 mm thick half-way to the margin, tough, white (1A1). Lamellae subventricose, free to adnexed, crowded; lamellulae in 1–2 tiers, white (1A1), 3–5 mm wide; lamellar edge eroded. Stipe 3–4 × 1–2 cm, central, cylindrical, rarely subbulbous at the base, smooth; context solid, fibrous, white (1A1). Annulus absent. Pseudorhiza terete, tapering downwards, surface grey (1D1–2) to dark grey (1F1–1F2), smooth; context solid, fibrous. Odour slightly fragrant. Taste not distinctive.
Basidia of two conspicuously different types by the sterigmata apex acute or obtuse, first type rather abundant, sterigmata apex acute, clavate, mostly 2–spored, sometimes 4–spored, 20–30 × 7–15 μm, av. 25 ± 2.4 × 11 ± 1.8 μm, sterigmata 1–4 μm long; the second type fewer in number, sterigmata obtuse, clavate, mostly 2–spored, sometimes 4–spored, 24–32 × 8–15 μm, av. 27 ± 2.2 × 10 ± 1.1 μm, sterigmata 2–3 (–5) μm long. Basidiospores [139/2/2] 6.5–10.2 (–11.1) × (3.9–) 4.5–8.2 (–9.1) μm, Lm × Wm = 8.6 ± 1.0 × 5.9 ± 0.8 μm, Q = 1.2–1.8, Qm = 1.47 ± 0.16, broadly ellipsoid to ellipsoid, colorless, thin-walled, smooth. Hymenophoral trama regular, parallel, 150–200 μm wide, made up of thin-walled, ellipsoid to clavate inflated cells hyphae 20–28 μm wide, filamentous hyphae abundant, 3–6 μm wide. Subhymenium 10–20 μm thick, with 1–2 layers of ovoid, subglobose, fusiform, ellipsoid or irregular cells, 7–13 × 3–6 μm. Cheilocystidia 14–37 × 13–23 μm, av. 23 ± 9.1 × 18 ± 4.9 μm, ellipsoid, obovoid to broadly clavate, thin-walled. Pleurocystidia similar to cheilocystidia in shape, 33–50 × 19–32 μm, av. 37 ± 9.1 × 25 ± 5.8 μm. Lamellar edge heteromorphous, more in number of cheilocystidia. Pileipellis 2-layered, suprapellis an ixocutis, 9–39 × 3–5 μm av. 23 ± 8.1 × 4 ± 0.5 μm, cylindrical hyphae with obtuse apex, thin-walled, hyaline at places in KOH; subpellis made up of inflated elements, subcylindrical, 17–49 × 10–18 μm av. 34 ± 9.2 × 13 ± 2.4 μm. Clamp connections not seen in any tissues.
Habitat and distribution: Solitary above underground termite nests; basidiomata occurring in summer. Known from southwestern China.
Additional material examined: China. Yunnan Province: Kunming city, Shilin county, Banqiao town, 11 July 2019 alt. 1500 m, J. He (HKAS 124502); ibid, 11 July 2019, alt. 1350 m, S.M. Tang (KHAS 124503); Yuxi city, Eshan county, 7 August 2019, alt. 1480 m, S.M. Tang (HKAS 124517).
Notes: Termitomyces yunnanensis is distinguished from other Termitomyces species by its clearly striated pileus surface, medium grey, olive grey, light grey to greenish grey at center, light grey towards margin on the pileus surface; perforatorium dark grey and umbonate, thin-walled or thick-walled basidia, ellipsoid, obovoid to broadly clavate cheilocystidia and pleurocystidia. According to our multi-locus phylogenetic analyses, T. yunnanensis was clustered together with T. subumkowaan Mossebo and T. robustus. However, T. subumkowaan has yellowish to brownish grey pileus, obtuse perforatorium concolorous with pileus, stipe cylindrical, bulbous at the base, and pleurocystidia extremely rare (Mossebo et al. 2002; Mossebo et al. 2017). Termitomyces robustus has bigger pileus (7–11 cm), pileus grey, often rimose-squamulose when dry, perforatorium concolorous with pileus, acute and bigger perforatorium (Sitotaw et al. 2015). Morphologically, T. medius R. Heim & Grassé, T. mammiformis, T. griseiumbo and T. striatus are similar to T. yunnanensis in having a clearly striated pileus surface. However, T. medius has smaller pileus (2.2–2.9 cm), and acute perforatorium, reflexed pileus margin when mature, smaller basidiospores (6–8 × 4–4.8 μm) and basidia (17–20 × 7–7.5 μm), pleurocystidia (25–40 × 12–25 μm) narrowly utriform, ovoid to obovoid (Heim 1977). Termitomyces mammiformis has subconical scales on the pileus surface, and an annulus on the stipe (Heim 1977). Termitomyces grisumbo has ochraceous pileus, and relatively bigger pileus (12–15 cm), and smaller basidiospores (5.5–7 × 3.5–4.5 μm), pleurocystidia abundant and polymorphic, clavate to pyriform, with one or more transverse septa (Mossebo et al. 2002).
Termitomyces striatus originally described from Sierra Leone (Africa), has clear striae on the pileus, ring of scales on the pseudorhiza, and small basidiospores (6.5–7.7 × 4–5 μm) (Heim 1977). However, T. striatus was divided 10 formed (Mossebo et al. 2009), namely f. annulatus, f. striatus, f. ochraceus, f. bibasidiatus, f. griseus, f. griseiumboides, f. subumbonatus, f. brunneus, f. pileatus and f. subclypeatus. However, according to the phylogenetic analysis of nrLSU and mtSSU sequence in Mossebo et al. (2017), f. striatus (tgf99), f. bibasidiatus (DM280), f. subumbonatus (DM208) and f. subclypeatus (DM151, DM370) were in a different species-level clade, and should therefore be considered as different species. Termitomyces f. bibasidiatus, f. subumbonatus, f. subclypeatus were originally described from Cameroon (Africa) and these species are morphologically different from T. yunnanensis. Termitomyces f. bibasidiatus has relatively long pseudorhiza (20–60 cm), pale, reddish grey to brownish orange yellow pileus, and globose to ovoid pileipellis cells (Mossebo et al. 2017). An annulus is present in Termitomyces f. subumbonatus (Mossebo et al. 2002), but absent in T. yunnanensis. Termitomyces f. subclypeatus has whitish orange to pale orange pileus with a greyish yellow to brownish orange perforatorium (Mossebo et al. 2017).
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.