Truncocolumella pseudocolumella L. Li, S. H. Li & Y. Wang 2024, sp. nov.

Truncocolumella pseudocolumella L. Li, S. H. Li & Y. Wang sp. nov. Materials Type status: Holotype. Occurrence: catalogNumber: HKAS 131259; recordNumber: L 2327; recordedBy: Shu-Hong Li; associatedSequences: KP 090063, KP 090064; occurrenceID: C1F523CC-76F3-573A-8065-139715C2CC02; Taxon: taxonID: MB 851721; scientificNameID: Truncocolumella pseudocolumella; Location: continent: Asia; country: China; stateProvince: Sichuan; municipality: Ganzi; locality: Yala Snow Mountain; verbatimElevation: 3772.4 m; verbatimLatitude: 30 ° 31 ′ N; verbatimLongitude: 101 ° 37 ′ E; Identification: identificationID: HKAS 131259; identifiedBy: Lin Li; Event: year: 2012; month: August; day: 19; habitat: in the forest of Quercus guyavifolia H. Lév. Type status: Other material. Occurrence: catalogNumber: HKAS 95533; recordedBy: Shan-Ping Wan; associatedSequences: GenBank: OR 631922; occurrenceID: E10A3DB1-A334-5221-8BED-5D60FE32F4DA; Taxon: scientificName: Truncocolumella pseudocolumella; Location: higherGeography: Hengduan Mountains area; country: China; stateProvince: Sichuan; county: Ganzi; Identification: identificationID: HKAS 95533; identifiedBy: Lin Li; Event: year: 2014; month: August; day: 22; habitat: in the forest of Pinus Type status: Other material. Occurrence: catalogNumber: HKAS 95534; recordedBy: Shan-Ping Wan; associatedSequences: GenBank: OR 631923; occurrenceID: 9ACD3595-0888-58BC-9057-6F0AECF08031; Taxon: scientificName: Truncocolumella pseudocolumella; Location: higherGeography: Hengduan Mountains area; country: China; stateProvince: Sichuan; county: Ganzi; Identification: identificationID: HKAS 95534; identifiedBy: Lin Li; Event: year: 2014; month: August; day: 22; habitat: in the forest of Pinus Description Basidiomata irregularly depressed-globose to pyriform, with a yellowish-tawny (4 C 8) rhizomorphic base, 1.5–3.0 cm in diameter, the surface typically smooth and dry in appearance, light yellowish-tawny (4 C 5) with yellowish-brown (4 C 8) rhizomorphs, colour unchanged on bruising or exposure, elastic, very mature basidiomata deliquesce like Rhizopogon (Fig. 1 A). Odour light and pleasant. Peridium 102–160 μm thick, not separating or evanescent from the gleba at maturity, composed of two layers: outer layer 52–73 μm thick, reddish-tawny (7 D 7) interwoven hyphae of 1–1.5 μm diameter. The inner layer 40–86 µm thick, consisting of brownish-hyaline nearly parallel interwoven hyphae of 0.5–1.5 μm diameter (Fig. 1 D). The boundary between the inner and outer layers gradually transitioning, with the changes in hyphae arrangement direction and hyphae colour. The clamp connection clearly visible, dry peridium becoming black (4 F 4) when encountering 5 % KOH (Fig. 1 B and C). Gleba pale white when immature, light brown to tawny at maturity, unchanging on bruising or exposure, cavities relatively small, spongy, lacking obvious columnar or dendroid radiating columella (Fig. 1 A). Trama (56.0 –) 62.5–85.0 μm, composed of hyaline almost parallel hyphae. Hymenium present on cavities surface. Basidia narrowly clavate, (15.0 –) 17.2–19.5 (– 22.4) × 3.5–6.5 (– 7.0) μm, 2-4 - spored. Sterigmata 2–3 μm (Fig. 1 E, G, H and I). Basidiospore ellipsoid, smooth, 7.5–10.0 (– 11.0) × 4.0–5.0 (– 5.6) μm, grey to brownish (7 D 5) in mass, as seen individually, almost hyaline, typically 1–2 guttulate, infrequently 3 - guttulate (Fig. 1 F and J), changing to blue in lactophenol cotton blue, not obvious discolouration in Melzer's reagent. Diagnosis Differs from other species in the genus Truncocolumella in the basidiomata devoid of any columnar. Etymology Pseudocolumella, referring to the absence of the columella. Distribution China, Sichuan Province. Ecology Gregarious in the soil associated with Quercus guyavaefolia and Pinus sp. Notes Notes: The genus Truncocolumella currently includes three species: T. citrina, T. occidentalis and the newly described T. pseudocolumella in this study. Based on the original literature descriptions of the species T. citrina (Zeller 1939, Smith and Singer 1959) and the re-examination of the type specimens of T. citrina and T. occidentalis by Malençon and Zeller (Malençon and Zeller 1940), we compared the key distinguishing features of these three species. In terms of macroscopic characteristics, T. pseudocolumella differs from other species in the genus Truncocolumella in the basidiomata devoid of any columnar. Furthermore, the basidiomata of T. citrina have a diameter of 2–4 cm, which is comparable in size to those of T. pseudocolumella (1.5–3 cm), but they are two to three times larger than T. occidentalis. The basidiomata surfaces of T. citrina are distinctly citrine yellow, those of T. pseudocolumella are yellowish-tawny, while T. occidentalis has white basidiomata, although the colour of T. occidentalis remains uncertain due to preservation in alcohol. Microscopically, T. citrina has ellipsoid spores measuring 6–10 × 3.5–5.0 μm, with individual spores appearing nearly hyaline. Similarly, T. pseudocolumella has ellipsoid spores measuring 7.5–10.0 × 4.0–5.0 μm, also nearly hyaline, showing close resemblance between the two. According to Malençon's description (Malençon and Zeller 1940), the spores of T. citrina are clearly shorter, more oval and of more irregular shape than those of T. occidentalis, in which these bodies are long-elliptic or sometimes subcylindrical. Molecular analysis further demonstrates that T. pseudocolumella is distinct from T. citrin, with high support for their separation into different species.