Absidia viridis Z. Y. Ding, Yang Jiang, Yi Xin Wang & X. Y. Liu, 2025

Ding, Zi-Ying, Ji, Xin-Yu, Tao, Meng-Fei, Jiang, Yang, Liu, Wen-Xiu, Wang, Yi-Xin, Meng, Zhe & Liu, Xiao-Yong, 2025, Unveiling species diversity within early-diverging fungi from China IV: Four new species of Absidia (Cunninghamellaceae, Mucoromycota), MycoKeys 119, pp. 29-46 : 29-46

Absidia viridis Z. Y. Ding, Yang Jiang, Yi Xin Wang & X. Y. Liu sp. nov.

Fig. 4

Type.

China • Yunnan Province, Mojiang Hani Autonomous County, Puer City (23°29'93"N, 101°39'17"E, altitude 1471.21 m), from soil, 4 July 2024, Z. Y. Ding and X. Y. Liu, holotype HMAS 353365 , ex-holotype living culture CGMCC 3.28539 (= XG 09563-3) .

Etymology.

The viridis (Lat.) refers to the light green colony on PDA.

Description.

Hyphae branched, hyaline at first, light green when mature, aseptate when young, septate with age. Stolons branched, smooth, hyaline, brownish, septate, 7.8–12.1 µm in diameter. Rhizoids finger-like, rarely present, hyaline, unbranched. Sporangiophores arising from stolons, erect or slightly bent, single or 2–4 in whorls, unbranched or branched 1–2 times, hyaline, 9.7–472.5 µm long, 6.5–10.7 µm wide, with a septum 10.4–18.3 µm below apophyses. Sporangia circular, elliptic, multi-spored, smooth, deliquescent-walled, colorless in youth, pigmented when old, 21.0–59.6 µm long, 17.7–51.4 µm wide. Columellae mostly spherical, occasionally hemisphere, conical, smooth, hyaline, 8.7–28.4 µm long, 11.1–31.7 µm wide. Apophyses funnel-shaped, hyaline, slightly pigmented, 5.4–14.3 μm high, 6.8–18.3 µm wide at the base, and 12.2–26.5 µm wide at the top. Projections evident, mostly strip-shaped, 2.2–7.8 µm long, 1.6–5.9 µm wide. Collars present or absent; if present, 5.4–10.2 µm long. Sporangiospores cylindrical, smooth, hyaline, 2.1–4.2 µm long, 1.6–3.1 µm wide. Chlamydospores absent. Zygospores not found.

Culture characteristics.

Colonies on PDA at 25 ° C for 7 days, reaching 80 mm in diameter, exhibiting an average growth rate of approximately 9.0– 11.4 mm / day, hyaline at first, light green when mature, regular in reverse.

Maximum growth temperature.

29 ° C.

Additional specimen examined.

China • Yunnan Province, Mojiang Hani Autonomous County (23°29'93"N, 101°39'17"E, altitude 1471.21 m), Puer City , from a soil sample, 4 July 2024, Z. Y. Ding and X. Y. Liu, living culture XG 09563-2 .

Notes.

In the phylogenetic tree of SSU-ITS-LSU- Act - TEF 1 α, two strains of the A. viridis sp. nov. formed a fully supported independent clade (MLBV = 100, BIPP = 1.00; Fig. 1 ), closely related to A. varians ( Zhao et al. 2023) . These two species were sensibly distinguished by the morphology of stolons, rhizoids, sporangiophores, columellae, apophyses, projections, sporangiospores. The maximum width of the stolons of A. viridis were wider than those of A. varians (12.1 µm vs. 8.5 µm). A. viridis was significantly different from A. varians in terms of rhizoid: the former was finger-like and unbranched, while the latter was root-like and multi-branched. The maximum sporangiophores length of A. viridis were shorter than those of A. varians (472.5 µm vs. 480.0 µm). The columellae of A. viridis presented conical shape, but A. varians absented. A single projection of one shape was observed at the apex of columellae in A. viridis , while 1–2 projections of three shapes in A. varians . The apophyses of the top width and base width in A. viridis were wider than those in A. varians , both at the top (12.2–26.5 µm vs. 10.5–22.5 µm) and at the base (6.8–18.3 µm vs. 5.5–11.0 μm). The apophysis-underneath septum grew at a closer distance in A. viridis than in A. varians (10.4–18.3 µm vs. 13.5–19.0 µm). The sporangiospores shape of A. viridis possessed mainly one kind, while A. varians possessed three kinds. Physiologically, the maximum growth temperature of A. viridis was one degree higher than that of A. varians (29 ° C vs. 28 ° C) ( Zhao et al. 2023).

Figures

Figure 1. The maximum likelihood phylogenetic tree of Absidia based on concatenated sequences of ITS rDNA, LSU rDNA, TEF 1 α, Act, and SSU rDNA, with Cunninghamella blakesleeana and C. elegans as outgroups. Maximum likelihood bootstrap values (MLBV ≥ 70 %) and Bayesian inference posterior probabilities (BIPP ≥ 0.9) are shown at the nodes, separated by slashes “ / ”. Ex-type or ex-holotype strains are indicated in bold black with an asterisk “ * ”. Strains obtained in this study are highlighted in red. Some branches are shortened for overall tree layout, indicated by “ // ”, with “ × ” denoting the fold of shortening. The scale bar at the bottom left represents substitutions per site.

Figure 4. Morphologies of Absidia viridis ex-holotype CGMCC 3.28539. a, b. Colonies on PDA; a. Obverse; b. Reverse; c, d. Sporangium; e – h. Columellae, collars, projections, and septa; i. Whorled sporangium; j. Branched sporangiophores; k. Rhizoids; l. Sporangiospores. Scale bars: 10 μm (c – l).