Annulohypoxylon violaceopigmentum Sir & Kuhnert

Rathnayaka, Achala R., Chethana, K. W. Thilini, Manowong, Areerat, Bhagya, Amuhenage T., Win, Hsan, Tun, Zaw L., Mapook, Ausana & Hyde, Kevin D., 2025, Taxonomy, phylogeny, and bioactive potential of Xylariales (Sordariomycetes, Ascomycota) from Thailand: novel species discovery, new host and geographical records, and antibacterial properties, MycoKeys 120, pp. 35-117 : 35-117

Annulohypoxylon violaceopigmentum Sir & Kuhnert , Fungal Diversity: 10.1007/s13225-016-0377-6, [9] (2016)

Fig. 9

Description.

Saprobic on the dead wood of Syzygium polyanthum . Sexual morph: Ascostromata 8–15 mm long × 5–10 mm broad and 0.5–1.2 mm thick (x ̄ = 12 × 5.5 × 0.8 mm, n = 10), hemispherical, effused-pulvinate, clustered, developing within cuticle, surface black, carbonaceous. Ascomata 0.4–0.5 mm high × 0.3–0.4 mm diam. (x ̄ = 0.45 × 0.35 mm, n = 10), immersed in the stroma, subglobose to globose, black, ostioles papillate, encircled with a flattened truncatum-type disc 0.2–0.25 mm diam. (x ̄ = 0.24 mm, n = 5). Hamathecium 1–2 μm wide, comprising long, hyaline, unbranched, aseptate paraphyses. Asci 74–110 × 5–7 μm (x ̄ = 97 × 6.7 μm, n = 20), the spore-bearing parts 70–77 µm long with stipes 29–32 µm long, 8 - spored, unitunicate, cylindrical, with an apical ring not bluing in Melzer’s iodine reagent. Ascospores 7–10 × 4–6 μm (x ̄ = 8.7 × 4.6 μm, n = 40), uniseriate, one-celled, inequilaterally ellipsoidal with narrowly rounded ends, hyaline when immature, becoming dark brown at maturity, guttules at immature stage, with a spore length straight germ slit. Asexual morph: Undetermined.

Culture characters.

Ascospores germinated on the PDA within 24 hours at 25 ° C. Germ tubes are produced from both sides of the ascospore. Colonies on the PDA reaching 2–2.5 cm diam. after five days at 25 ° C, circular in shape, white at first, cottony, white color in the front view, brown in the middle, and pale brown at the margin in the reverse view.

Material examined.

Thailand • Chiang Rai, Phan District, Sai Khao, forest area near Wat Udom Waree , on decaying wood of Syzygium polyanthum ( Myrtaceae ), 05 July 2024, Achala Rathnayaka, AA 31 ( MFLU 24-0528 ); living culture MFLUCC 24-0610 .

Known distribution and hosts.

Thailand (on dead wood, Syzygium polyanthum ) ( Kuhnert et al. 2017; this study).

Notes.

The morphological description of our collection ( MFLUCC 24-0610 ) aligns with the holotype of A. violaceopigmentum ( MFLU 14-0314 ), including effused-pulvinate ascostromata; black, ostioles, papillate ascomata encircled by a flattened truncatum-type disc; 8 - spored, cylindrical asci; and brown, unicellular, inequilaterally ellipsoidal ascospores with broadly rounded ends and a straight germ slit along the spore length ( Kuhnert et al. 2017). Based on the multi-gene phylogenetic analyses (ITS, LSU, β-tub, and rpb 2), our strain ( MFLUCC 24-0610 ) clusters with the ex-type strain of A. violaceopigmentum ( MFLUCC 14-1225 ) with 97 % ML bootstrap and 0.85 PP support (Fig. 3 ). Considering the morpho-molecular evidence, we conclude that our collection is a new host record of A. violaceopigmentum on Syzygium polyanthum in Thailand.

Figures

Figure 3. Phylogram generated from ML analysis based on the combined dataset of ITS, LSU, β-tub, and rpb 2. The tree is rooted to Biscogniauxia petrensis (HKAS 102388). Bootstrap support values for ML ≥ 70 % and Bayesian posterior probabilities (PP) ≥ 0.90 are noted at the nodes. Strain numbers are noted after the species names. Strains isolated in this study are represented in blue, and type strains are in bold.

Figure 9. Annulohypoxylon violaceopigmentum on the dead wood of Syzygium polyanthum (MFLU 24-0528, a new host record). a. Substrate; b, c. Appearance of ascomata on the host (ostiolar discs indicated by the arrow); d. Horizontal section through ascomata; e. Paraphyses; f – k. Asci; l. Ascus apical apparatus (not stained in Melzer’s reagent); m – q. Ascospores (q: arrow indicates the germ slit); r A germinated ascospore; s, t Colony on the PDA (s upper, t lower). Scale bars: 2 mm (b); 500 μm (c); 200 μm (d); 20 μm (e – k, r); 5 μm (l – q).