Amphisphaeria pseudomicheliae Z. L. Tun & K. D. Hyde, 2025

Tun, Zaw Lin, Bundhun, Digvijayini, Bhunjun, Chitrabhanu S., Maharachchikumbura, Sajeewa S. N., Thiyagaraja, Vinodhini, Al-Otibi, Fatimah & Hyde, Kevin D., 2025, The addition of six novel species and a new record of Amphisphaeria from northern Thailand, MycoKeys 125, pp. 1-31 : 1-31

Amphisphaeria pseudomicheliae Z. L. Tun & K. D. Hyde sp. nov.

Fig. 6

Etymology.

Refers to the morphological similarity with Amphisphaeria micheliae .

Holotype.

MFLU 25-0074 .

Description.

Saprobic on decaying twigs. Sexual morph: Ascomata 202–273 μm high, 349–400 µm diam (xˉ = 246 × 337 µm, n = 5), immersed, visible as tiny pores, flat, solitary to aggregated, scattered, globose to subglobose, brown, ostiolate. Peridium 17–23 µm wide (xˉ = 20.6 µm, n = 5), two-layered; outer layer wide, dark brown, comprising thick-walled cells of textura angularis, inner layer comprising hyaline cells of textura angularis, thin-walled. Paraphyses 4–4.4 µm (xˉ = 4.2 µm, n = 5) wide, hyaline, longer than asci, filiform, guttulate, septate, embedded in a gelatinous matrix. Asci 84–97 × 7–9 µm (xˉ = 89.8 × 8.45 µm, n = 20), 8 - spored, unitunicate, cylindrical, with short pedicel, apically rounded and narrowed, with a J + inconspicuous apical ring. Ascospores 11–17 × 4–6 µm (xˉ = 15 × 5 µm, n = 20), uniseriate, fusiform, hyaline when immature, turning yellow to yellowish brown on maturity, 1 - septate, guttulate, smooth-walled, slightly constricted at septum, straight to slightly curved, surrounded by a thin mucilaginous sheath. Asexual morph: Not observed.

Material examined.

Thailand • Chiang Rai Province, Mae Fah Luang University premises ( 20°02′42″N, 99°53′41″E), on decaying dead twigs of an undetermined host, 06 July 2023, Zaw Lin Tun E 15 ( holotype MFLU 25-0074 ) .

Notes.

Amphisphaeria pseudomicheliae is closely related to A. micheliae , receiving robust support with 97 % ML and 1 PP bootstrap support (Fig. 1 ). However, it can be distinguished from A. micheliae by its larger ascomata (202–273 × 349–400 µm vs. 180–210 × 225–370 µm) and smaller asci (84–97 × 7–9 µm vs. 92–135 × 7–10.5 μm) ( Samarakoon et al. 2020). Additionally, the ascospores of A. pseudomicheliae are smaller (11–17 × 4–6 µm) than those of A. micheliae (15.5–21 × 6–7.5 μm) ( Samarakoon et al. 2020). Amphisphaeria pseudomicheliae has a thin mucilaginous sheath, whereas A. micheliae lacks ( Samarakoon et al. 2020). The genetic analysis reveals interspecies distances of 4.3 % base pair differences (without gaps) in the ITS (23 / 524 bp) and 0.43 % in the LSU (4 / 873 bp) between A. pseudomicheliae ( MFLU 25-0074 ) and A. micheliae ( HKAS 107012). Amphisphaeria micheliae is uncertain since our new species lack protein coding genes. Thus, numerous collections with the protein coding genes can provide better resolution between the species. Amphisphaeria pseudomicheliae is described as a new species based on its distinct morphology and phylogenetic data.

Figures

Figure 1. Phylogram generated from ML analysis based on combined LSU, ITS sequence data. Bootstrap support values for ML ≥ 75 % and PP ≥ 0.90 are indicated near the corresponding nodes. The tree is rooted with Beltrania rhombica (CBS 123.58), Beltraniella endiandrae (CBS: 137976), and Beltraniopsis longiconidiophora (MFLUCC 17-2139). Type and reference strains are in bold, while the novel strains are in bold red.

Figure 6. Amphisphaeria pseudomicheliae (MFLU 25-0077, holotype). A. Host; B. Appearance of ascomata on host (arrows indicate ascomata as tiny pores on host surface); C. Vertical section through an ascoma; D. Vertical section of peridium; E. Paraphyses; F. An inconspicuous J + apical ring; G – I. Asci; J – Q. Ascospores; Q. An ascospore with a thin gelatinous sheath (in Indian ink). Scale bars: 100 μm (C); 10 μm (D – F); 20 μm (G – I); 10 μm (J – Q).