Pileus (1.2–)2.2–4.5(–5.4) cm, cuspidate, conical becoming applanate when mature, with small and obtusely pointed perforatorium; surface brownish gray (9D2) or grayish brown (5D3) at center; mid of center is darker: brownish gray (9E2) or gray (7E1); reddish gray (9B2), brownish-gray (6C2), grayish-white (1B1), light gray (1C1) elsewhere and mixed with tiny white filamentous striate (1A1); glabrous and smooth, paling toward margin, radially striate; margin straight, splitting when mature. Lamellae free, (1.0)2.0–4.0(5.0) mm wide, white (1A1) when young and becoming pinkish white (7A2) when mature, crowed, with lamellulae. Stipe (2.7) 4.5–7.0(7.5) × (0.1)0.2–0.4(0.5) cm, central, cylindrical, equal; the base of stipe abrupt or forming a root-like terminal of (1.5–)2.7–4.5(–7.2) × (0.05–)0.15–0.25(–0.4) cm size underground level, in contact with termites’ fungi-garden and mixed substrates such as wood, soil and litter; surface white(1A1), smooth and glabrous, longitudinally striate, fibrous and fistulose to broadly fistulose, frangible, of longitudinally parallel hyphae, thin-walled and hyaline, 2.0–7.0(10) μm diam. Context narrow, fleshy, white (1A1), (0.5–)1–2.5(–4) mm wide, of inflating hyphae, thin-walled and hyaline, normal hyphae 2.5–7.5 μm diam. Basidiospore colorless, ovoid to ellipsoid, [100/7/4] 9.0–10.0(–10.5) × 5.5–6.5(–7.5) μm, Q= 1.0–2.0, Qm =1.2 ± 0.2; thinwalled and subhyaline. Basidia 20–35 × 7.0–10.0 μm, clavate, bearing four sterigmata, thin-walled, subhyaline. Cheilocystidia 40–80 × 12–31 μm, clavate to pyriform, thin-walled and hyaline. Pleurocystidia 47–75(–80) × 14–32 μm, similar to cheilocystidia. Pileipellis comprising 2 layers, lower layer cells are much bigger than upper layer, hyphae 2–5 μm diam in upper layer, in lower layer, hyphae 10–35 μm diam, radial hyphae, ovoid, a repent epicutis of narrow, repent, thin-walled. (Figs. 1–2)
Index Fungorum no: IF552544, FoF number: 02690
Etymology: the etymology refers to the fragile stipe of the new species.
Holotype: China. Yunnan Province: Xishuangbanna, Mengsong Village, 21.49894°N, 100.49433°E, alt. 1656 m, August 14 2012, Lei Ye (HKAS88912).
Diagnosis: The new species is characterized by small basidiocarps, with a hollow and fragile stipe. It grows in shallow soils that are rich in organic matter, and is associated with termites. Micro-morphologically, it is characterized by larger basidia (20–35 × 7.0–10.0 μm) and cystidia (Cheilocystidia 40–80 × 12–31 μm; Pleurocystidia 47–75 (–80) × 14–32 μm), relative to other members of the genus Termitomyces.
Habitat and Distribution: Usually scattered (few solitary) on soil with decaying litter under which termites have built their nests, associated with Camellia sinensis and Castanopsis calathiformis trees, Yunnan Province, China.
Material examined: CHINA. Yunnan Province: Xishuangbanna, Mengsong Village, 21.49894°N, 100.49433°E, alt. 1656 m, August 14 2012, Lei Ye (HKAS88912, holotype, Accession KY214475); Ibid., Mengsong Village, September 20 2012, Lei Ye (HKAS88909, paratype, Accession KY214476); Ibid. Mengsong Village, June 23 2013, Lei Ye (HKAS88906, paratype, Accession KY214477); Ibid. Mengsong Village, August 14 2012, Lei Ye (HKAS88913, paratype); Ibid.