Absidia pacifica M. F. Tao, H. Zhao & X. Y. Liu, 2024

Tao, Meng-Fei, Ding, Zi-Ying, Wang, Yi-Xin, Zhang, Zhao-Xue, Zhao, Heng, Meng, Zhe & Liu, Xiao-Yong, 2024, Unveiling species diversity within early-diverging fungi from China II: Three new species of Absidia (Cunninghamellaceae, Mucoromycota) from Hainan Province, MycoKeys 110, pp. 255-272 : 255-272

Absidia pacifica M. F. Tao, H. Zhao & X. Y. Liu sp. nov.

Fig. 2

Type.

China • Hainan Province, Changjiang County, Bawangling National Forest Park (19.08593 ° N, 109.12275 ° E), from soil, 14 Oct 2023, M. F. Tao and X. Y. Liu, holotype HMAS 352924 , ex-holotype living culture CGMCC 3.27497 , living cultures XG 06955-16 or SAUCC 6955-16 .

Etymology.

The epithet pacifica (Lat.) refers to the pacifier-shaped projections.

Description.

Mycelia hyaline at first, becoming brownish when mature, aseptate or irregularly septate with age, branched. Stolons hyaline to brownish, smooth, branched, 4.2–8.8 µm in diameter. Rhizoids well-developed, root-like, hyaline, simply branched. Stolons present. Sporangiophores growing from stolons, erect or slightly bent, unbranched, hyaline, single or 2–6 in whorls, 79.1–128.7 µm long, 3.0–6.5 µm wide, sometimes with a swelling beneath sporangia, with a septum 11.3–29.6 µm below apophyses. Apophyses obvious, small, hyaline, slightly pigmented, 4.6–8.4 µm wide at the base and 9.8–20.0 µm wide at the top. Sporangia globose, smooth, dark brown, deliquescent-walled, 23.6–39.2 µm long, 19.0–33.7 µm wide. Collars absent or present. Columellae mostly globose, occasionally oval, 12.8–22.1 µm long, 9.5–21.8 µm wide. Projections pacifier-like, 4.1–7.5 µm long, 1.8–3.9 µm wide. Sporangiospores variously shaped, mostly cylindrical or subglobose, smooth, hyaline, 2.8–6.2 µm long, 2.0–3.9 µm wide. Chlamydospores absent. Zygospores not found.

Culture characteristics.

Colonies on PDA at 25 ° C for 7 days, reaching 85 mm in diameter, exhibiting an average growth rate of approximately 11.4–12.1 mm / d, white initially, brown with age, irregularly concentrically zonate with ring, flower-shaped, irregularly in reverse, with adjoining satellite colonies at edge.

Maximum growth temperature.

35 ° C.

Additional specimen examined.

China • Hainan Province, Changjiang County, Seven Forks (19.11750 ° N, 109.15000 ° E), from soil, 11 Apr 2023, M. F. Tao and X. Y. Liu, living culture XG 04136-4 or SAUCC 413601 ; • China, Hainan Province, Changjiang County, Bawangling National Forest Park (19.08593 ° N, 109.12275 ° E), from soil, 14 Oct 2023, M. F. Tao and X. Y. Liu, living culture XG 06955-15 or SAUCC 6955-15 .

Notes.

Phylogenetically, A. pacifica was closely related to A. edaphica . Morphologically, the sporangiophores of A. pacifica was longer than that of A. edaphica (3.0–6.5 µm vs 2.5–5.4 µm), and the distance between the septum and apophysis was shorter in A. pacifica than that in A. edaphica (11.3–29.6 µm vs 20–33.5 µm). The columellae of A. pacifica were larger than those of A. edaphica (9.5–21.8 × 12.8–22.1 μm vs 5–9.5 × 6.5–20 μm). Additionally, some columellae in A. pacifica lacked a collar structure. The overall length of spores in A. pacifica was slightly larger than that in A. edaphica (2.8–6.2 µm vs 3.5–5.5 µm), and the shape of sporangiospores in A. pacifica was more diverse. Physiologically, the maximum growth temperature for A. pacifica was lower than that of A. edaphica (35 ° C vs 36 ° C) ( Hurdeal et al. 2021).

Figures

Figure 2. Absidia pacifica (holotype: HMAS 352924) a obverse and reverse of the culture on PDA b, d, e sporangia c swellings in hyphae f, g columellae h rhizoids i sporangiospores. Scale bars: 10 μm (b – i).