Amphibambusa guangxiensis Z.Q. Yao, K. Habib & Q.R. Li, 2025

Amphibambusa guangxiensis Z.Q. Yao, K. Habib & Q.R. Li sp. nov. Fig. 2 View FIGURE 2

MycoBank No:859141

Etymology: The specific epithet " guangxiensis " refers to Guangxi Province, where the holotype specimen was collected.

Specimens examined — China, Guangxi Province, Fangchenggang city, Shiwandashan National Nature Reserve , longitude 108°2'31.58" E, latitude 21°57'12.34" N, altitude 300 meters, on dead bamboo culm, August 9 th, 2024, Zuquan Yao, 2024SWS85 (GMB4910, holotype; KUN-HKAS 146993, isotype, GMBC4910 ex-type) GoogleMaps ; GenBank accession numbers: ITS = PV617366 ; LSU = PV617364 About LSU .

Description: Saprobic on the surface of decaying bamboo culms, forming black round spots. Ascomata 780–1000 μm width, 640–710 μm height, immersed, solitary, scattered, globose to subglobose, black, ostiole at the center. Peridium 16–43 μm ( x = 28 μm, n = 10) width, composed of thick walled, hyaline to brown cells of textura angularis. Paraphyses 3.1–6.2 μm ( x = 4.4 μm, n = 10) width, filamentous, aseptate, thin-walled, with hyaline guttulate cells, non-septate. Asci 160–235 × 14.5–24.5 μm ( x = 190 × 19.3 μm, n = 30), 8-spored, unitunicate, cylindrical, short-stalked, with a J+, discshaped, subapical ring, bluing in Melzer’s reagent, 3.6–4.7 × 1.8–2.6 μm ( x = 4 × 2.3 μm, n = 30). Ascospores 26–34 × 7.3–9.8 μm ( x = 29.1 × 8.8 μm, n = 30), uniseriate, hyaline, fusiform, 1-septate at the center, slightly constricted at the septum, tapering at both ends, with longitudinal striations along the entire length of the ascospore, surrounded by a mucilaginous sheath of 11–16 μm ( x = 13.2 μm, n=10) thick. Anamorph: Undetermined.

Culture characteristics – Colonies on PDA, reached 3 cm diam. after one week, white, cottony, flat, dense, with slightly wavy margin. Not sporulating on OA nor on PDA after three months.

Additional specimens examined – CHINA, Guangxi Province, Fangchenggang city, Shiwandashan National Nature Reserve , longitude 108°2’31.60”E, latitude 21°57’12.32” N, altitude 300 meters, on dead bamboo culm,August, 2024, Q. R Li. Yulin Ren, 2024SWS311 (GMB4911; GMB4C911) GoogleMaps ; GenBank accession numbers: ITS = PV617365 ; LSU = PV617363 About LSU .

Notes: Phylogenetically ( Fig. 1 View FIGURE 1 ), Amphibambusa guangxiensis forms an independent clade, clearly distinguishing it from all the known species of the genus. Morphologically, A. guangxiensis resembles A. aquatica in the size of the ascomata (500–1000 μm diam., in A. aquatica ) and the asci (190–240 × 12–16 μm in A. aquatica ). Both species possess the largest asci in the genus, reaching up to 240 μm, while all other species have asci shorter than 200 μm (Manawasinghe et al. 2024). However, it differs in ascospore size (26–34 × 7.3–9.8 μm vs. 32–40 × 6–7.5 μm in A. aquatica ) and is also phylogenetically distant (Manawasinghe et al. 2024).

Amphibambusa hongheensis is similar in ascospore size to A. guangxiensis but differs in having smaller ascomata (350–600 μm diam. vs. 780–1000 μm diam. in A. guangxiensis ) with protruding carbonaceous papillae surrounded by a white margin, as well as smaller asci (118–160 × 14–18 μm vs. 160–235 × 14.5–24.5 μm in A. guangxiensis ) ( Jiang et al. 2021).

Other Amphibambusa species are readily distinguished from A. guangxiensis by ascospore and asci dimensions. Amphibambusa cerosissimae has smaller asci (132–154 × 13.2–16.5 µm) and smaller ascospores (18.7–22.4 × 4.5–6.6 µm) ( Liu et al. 2025). Amphibambusa aureae is characterized by 90–190 μm in length asci and smaller ascospores (15–22.5 × 5–7.9 μm) with a thinner gelatinous sheath (2.5–7 µm) ( Zhou et al. 2024). Amphibambusa bambusicola View in CoL differs from A. guangxiensis in having smaller asci (150–200 μm in length) and smaller ascospores (25–27 × 5.5–6 μm), with ascospores of A. guangxiensis being slightly constricted at the septum, while those of A. bambusicola View in CoL are deeply constricted ( Liu et al. 2015). Amphibambusa subbambusicola is distinguished by its non-striated ascospores and smaller asci (117–162 × 11.8–15.3 µm) and ascospores (25.7–29.9 × 6.3–7.9 µm) compared to A. guangxiensis ( Liu et al. 2025) .