Absidia tibetensis X. Y. Ji, H. Zhao & X. Y. Liu 2025, sp. nov.

Absidia tibetensis X. Y. Ji, H. Zhao & X. Y. Liu sp. nov. Fig. 6 Type. China • Tibet, Xigaze City, Yadong Country (27°21'53"N, 88°58'26"E, 2827 m), from soil, 1 Oct 2024, X. Y. Ji and X. Y. Liu, holotype HMAS 353361, ex-holotype living culture CGMCC 3.28534 (= XG 00415-1). Etymology. The tibetensis (Lat.) refers to the Tibet Autonomous Region of China, where the type was collected. Description. Colonies on PDA at 26 ° C for 5 days, reaching 53 mm in diameter, slow-growing with a rate of 10.6 mm / d, white at first and gradually turning to light brown; the reverse side of the colony resembles a petal-shaped, regularly at reverse. Rhizoids root-like, always branched, with a septum at the top. Hyphae hyaline to slightly gray, 5.0–10.0 µm (x – = 7.1 µm, n = 20) in diameter, sometimes ampulliform-shaped swollen. Stolons hyaline, slightly brownish, branched, smooth, 3.2–11.0 µm (x – = 6.0 µm, n = 15) in diameter. Sporangiophores erect or slightly bent, unbranched or simple branched, smooth, single or 2–5 in whorls, monopodial or sympodial, 14.7–144.0 × 2.5–5.7 µm (x – = 78.2 × 4.0 µm, n = 15), sometimes with a swelling beneath sporangia. Sporangia globose to pyriform, smooth, multi-spored, deliquescent-walled, 11.0–30.2 × 11.1–26.6 µm (x – = 21.5 × 17.1 µm, n = 15), and with a septum 8.4–20.0 µm (x – = 15.6 µm, n = 15) below apophyses. Apophyses obvious, funnel-shaped, gradually widening from the base to the top, 2.5–9.6 µm (x – = 6.7 µm, n = 15) high, 3.2–8.3 µm (x – = 4.2 µm, n = 15) wide at the base, and 7.4–19.0 µm (x – = 11.2 µm, n = 15) wide at the top, hyaline, light brown. Collars absent or present. Columellae conical, nearly globose, occasionally oval, 8.5–19.9 × 10.1–16.5 µm (x – = 11.3 × 11.8 µm, n = 15). Projections present or absent, hyaline when present, needle-pointed. Sporangiospores smooth, hyaline, mostly oval, 2.6–3.9 × 1.6–2.4 µm (x – = 3.6 × 2.1 µm, n = 20). Chlamydospores absent. Zygospores not found. Maximum growth temperature. 30 ° C. Additional specimen examined. China • Tibet, Xigaze City, Yadong County (27°21'53"N, 88°58'26"E, 2827 m), from soil, 1 October 2024, X. Y. Ji and X. Y. Liu, living culture XG 00415-3. Notes. In the molecular phylogeny, A. tibetensis was closely related to A. sichuanensis (Zhao et al. 2022 b). Morphologically, the maximum width of the hyphae in A. yunnanensis was greater than that in A. tibetensis (15.5 µm vs. 10.0 µm). Apophyses had a wider base width and top width in A. tibetensis (3.2–8.3 × 7.4–19.0 μm vs. 3.0–5.0 × 5.5–12.0 μm). The sporangiophore size was smaller in A. tibetensis (2.6–3.9 × 1.6–2.4 μm vs. 3.0–4.5 × 2.0–2.5 μm). The swelling on sporangiophores and hyphae was observed in A. tibetensis. The collars were not observed in A. sichuanensis. Physiologically, the maximum growth temperature of A. tibetensis was higher (30 ° C vs. 28 ° C).