Absidia collariata X. Y. Ji, H. Zhao & X. Y. Liu sp. nov. Fig. 2 Type. China • Yunnan Province, Yuxi City, Xinping Yi Dai Autonomous County, Ancient Tea Horse Road (23°57'28"N, 101°30'38"E, 2196.56 m), from soil, 5 Jul. 2024, X. Y. Ji and X. Y. Liu, holotype HMAS 353360, ex-holotype living culture CGMCC 3.28536 (= XG 08666-10-1). Etymology. The collariata (Lat.) refers to its long collars. Description. Colonies on PDA at 26 ° C for 5 days, reaching 68 mm in diameter, moderately fast growing with a rate of 13.6 mm / d, higher in the center than at margin, at first white, becoming grayish brown when mature, regular shape at reverse. Hyphae light-colored at first, becoming brown when mature, 4.7–9.4 µm (x – = 6.4 µm, n = 20) wide. Stolons branched, hyaline to light brown, smooth, septate, 5.1–6.3 µm (x – = 5.6 µm, n = 15) in diameter. Rhizoids well developed, root-like, branched. Sporangiophores growing on stolons, erect or slightly bent, mostly unbranched or simply branched, smooth, single or 2–4 in whorls, monopodial or sympodial, 21.7–213.5 × 2.3–5.4 µm (x – = 112.8 × 4.1 µm, n = 15). Sporangia globose to pyriform, smooth, hyaline, deliquescent-walled, 16.2–37.0 × 14.0–31.1 µm (x – = 24.2 × 23.2 µm, n = 15), and with a septum 8.8–17.9 µm (x – = 13.9 µm, n = 15) below apophyses; the septum is not obvious when young. Apophyses distinct, funnel-shaped, 6.0–9.5 µm (x – = 8.5 µm, n = 15) high, 5.1–8.8 µm (x – = 6.2 µm, n = 15) wide at the base, and 8.4–13.9 µm (x – = 10.7 µm, n = 15) wide at the top, darker brown when old. Collars present, obvious. Columellae nearly conical, sometimes subspherical to hemispherical, 8.1–13.8 × 7.7–14.9 µm (x – = 10.6 × 10.9 µm, n = 15). Projections absent or present, hyaline, single. Sporangiospores hyaline, smooth, mostly oval, 2.1–3.8 × 1.8–2.7 µm (x – = 3.1 × 2.3 µm, n = 20). Chlamydospores absent. Zygospores not found. Maximum growth temperature. 29 ° C. Additional specimen examined. China • Yunnan Province, Yuxi City (23°57'28"N, 101°30'38"E, 2196.56 m), from soil, 5 Jul. 2024, X. Y. Ji and X. Y. Liu, living culture XG 08666-10-2. Notes. In the molecular phylogeny, A. collariata was closely related to A. psychrophilia (Zhao et al. 2022 b). Morphologically, the width of stolons in A. collariata was smaller than that in A. psychrophilia (5.1–6.3 µm vs. 5.5–11 µm). Furthermore, the A. collariata has smaller sporangiophores (2.1–3.8 × 1.8–2.7 µm vs. 3.8–5 × 2.2–3.5 µm). The length and width of sporangiophore were also smaller in A. collariata than those in A. psychrophilia (21.7–213.5 × 2.3–5.4 µm vs. 193–288 × 4.5–9 µm). And the A. psychrophilia has larger sporangia (20–50 μm vs. 16.2–37.0 × 14.0–31.1 μm). Zygospores were not observed in A. collariata.

Published as part of Ji, Xin-Yu, Ding, Zi-Ying, Nie, Yong, Zhao, Heng, Wang, Shi, Huang, Bo & Liu, Xiao-Yong, 2025, Unveiling species diversity within early-diverging fungi from China V: Five new species of Absidia (Cunninghamellaceae, Mucoromycota), pp. 267-288 in MycoKeys 117 on pages 267-288, DOI: 10.3897/mycokeys.117.149185