The epithet refers to the host genus, Mesua, from which the fungus was isolated.

MFLU 25-0069.

Saprobic on decaying twigs of Mesua sp. Sexual morph: Ascomata 520–580 μm high, 260–290 µm wide (xˉ = 549 × 272 µm, n = 5), immersed, visible as black spots with tiny pores, flat, scattered or aggregated, globose to subglobose, ostiolate. Peridium 14–18 µm (xˉ = 15 µm, n = 5), two-layered; outer layer wide, comprising thick-walled, dark brown cells of textura angularis, inner layer thin, composed of hyaline textura angularis cells. Paraphyses 3–5 µm wide, hyaline, septate, longer than asci, narrow towards the apex. Asci 86–134 × 7–13 µm (xˉ = 115 × 9 µm, n = 20), 8-spored, unitunicate, cylindrical, with short pedicel, apically rounded, with a J+, apical ring. Ascospores 14–18 × 5–6.8 µm (xˉ = 15 × 6 µm, n = 20), uniseriate, ellipsoidal, hyaline when immature, turning sub-hyaline to pale brown at maturity, 1-septate, slightly constricted at the septum, guttulate, smooth-walled, lacking a sheath in Indian ink. Asexual morph: Not observed.

Colonies on MEA, reaching 4 cm diam. after 15 days at 27 °C, from above white to pale yellow radiating outwards, dense, circular to slightly irregular, flattened with smooth surface, with smooth margin; reverse pale brown in the middle, yellowish brown at the margin.

Thailand • Chiang Rai Province, Mae Fah Luang University (20°02′42″N, 99°53′41″E), on decaying dead twigs of Mesua sp. (Calophyllaceae), 02 October 2023, Zaw Lin Tun P11 (holotype MFLU 25-0069); ex-type culture MFLUCC 25-0197.

Phylogenetic analyses revealed that Amphisphaeria mesuae (MFLUCC 25-0197) clustered with Amphisphaeria hibiscicola (HKAS 136910) and Amphisphaeria umbrina (PRA JV24328) in (Fig. 1). The interspecies genetic distances between A. mesuae (MFLU25- 0069) and A. hibiscicola (HKAS 136910) showed the following base pair differences (without gaps): 5.7% for LSU (49/935 bp) and 11.18% for ITS (66/559 bp). Amphisphaeria mesuae (MFLUCC 25-0197) and Amphisphaeria umbrina (PRA JV24328) showed the following base pair differences (without gaps): 3.3% for LSU (28/844 bp) and 9.45% for ITS (54/571 bp). Morphologically, A. mesuae differs from A. hibiscicola by having taller ascomata (520–580 μm) compared to those of A. hibiscicola (212–450 μm), whereas A. hibiscicola has broader ascomata (456–570 μm wide) than A. mesuae (260–290 μm) (Sun et al. 2025). The asci of A. mesuae (86–134 × 7–13 µm) are smaller than those of A. hibiscicola (122–152 × 6–8 µm) (Sun et al. 2025). The ascospores of A. mesuae (14–18 × 5–6.8 µm) are ellipsoidal, while the ascospores of A. hibiscicola (8–14 × 3.5–5 μm) are fusiform (Sun et al. 2025). Amphisphaeria hibiscicola has a gelatinous sheath, whereas A. mesuae lacks a sheath (Sun et al. 2025

Morphologically, A. mesuae differs from A. umbrina by having higher ascomata (520–580 μm vs. 400–480 μm) but narrower width (260–290 μm vs. 560–640 μm) (Wang et al. 2004).The asci of A. mesuae (122–152 × 6–8 µm) are also smaller than those of A. umbrina (150–170 × 11–13 µm) (Wang et al. 2004). Similarly, the ascospores of A. mesuae (14–18 × 11–12 µm) are smaller than those of A. umbrina (18–22 × 6–8 μm) (Wang et al. 2004).

Based on the distinct morphology and phylogenetic evidence, along with the recommendations for species delineation proposed by Chethana et al. (2021) and Maharachchikumbura et al. (2021), we introduce A. mesuae as a new species.

Saprobic on dead twigs of Senna siamea. Sexual morph: Ascomata 308–320 µm high, 348–360 µm wide, (xˉ = 312 × 353 µm, n = 5), immersed, visible as black spots in light-coloured areas on the host, solitary, scattered, subglobose to oblate, papillate. Ostiole 100–106 µm high, 65–70 µm diam (xˉ = 102 × 67 µm, n = 5), centric. Peridium 45–58 µm (xˉ = 48 µm, n = 5) two-layered; outer layer thick, dense, made up of red-dish-brown cells of textura angularis; inner layer thin, comprising hyaline cells. Paraphyses 3–5 µm wide (xˉ = 4.4 µm, n = 5), hyaline, longer than asci, septate, guttulate, embedded in a gelatinous matrix. Asci 85–115 × 6.5–7 µm (xˉ = 101 × 6.8 µm, n = 20), 8-spored, unitunicate, cylindrical, thin-walled, short-pedicellate, apically rounded, with a J+, discoid apical ring. Ascospores 15–16 × 5–6 µm (xˉ = 15.5 × 5.9 µm, n = 20), uniseriate, oblong or narrowly fusiform, guttulate, hyaline when immature, turning sub-hyaline to olivaceous grey, 1-septate, slightly constricted at the septum, straight to slightly curved, smooth-walled, lacking a sheath in Indian ink. Asexual morph: Not observed.

Thailand • Chiang Rai Province, Mae Fah Luang University premises (20°02′42″N 99°53′41″E), on dead decaying twigs of Senna siamea (Fabaceae), 02 October 2024, Zaw Lin Tun T7, (MFLU 25-0077).

Based on the phylogenetic analyses, our strain (MFLU 25-0077) clustered with Amphisphaeria micheliae group (Fig. 1). Morphologically, our strain (MFLU25-0077) resembles the type of A. micheliae (MFLU 20-0172) (Samarakoon et al. 2020). The asci length of our collection (MFLU25-0077) measures 85–115 × 6.5–7 µm, while those of the type of A. micheliae (HKAS 107012) range from 92–135 × 7–10.5 µm (Samarakoon et al. 2020). The ascospore length of A. micheliae (MFLU 25-0077 and HKAS 107012) is also similar (15–16 × 5–6 µm vs. 15.5–21 × 6–7.5 µm) (Samarakoon et al. 2020). The comparison of inter-species genetic distances between our strain (MFLU25-0077) and HKAS 107012 reveals largely similar base pair differences in the LSU (99%) and ITS (99%) regions. Based on this morpho-phylogenetic evidence, we identify our isolate as A. micheliae. Previously, A. micheliae was isolated from dead twigs of Acer truncatum, Alstonia scholaris, Micromelum integerrimum, and Michelia alba in China and Thailand (Samarakoon et al. 2020; De Silva et al. 2022; Li et al. 2024; Pathirana et al. 2025). This is the first report of A. micheliae from Senna siamea in Thailand.

The epithet refers to the host genus, Mimusops, from which the fungus was isolated.

MFLU 25-0076.

Saprobic on the decaying branch of Mimusops elengi. Sexual morph: Ascomata 286–370 μm high, 364–455 µm wide, (xˉ = 321 × 397 µm, n = 5), immersed, visible as black spots with tiny pores, staining the host surface pale reddish brown around the ostioles, solitary, scattered to aggregated, globose to sub-globose. Ostiole central, prominent, 150–166 μm high, 82–84 µm wide (xˉ = 154 × 82 µm, n = 5). Peridium 12–25 µm (xˉ = 20 µm, n = 5), two-layered; outer layer thick, dense, reddish-brown cells of textura angularis, inner layer thin, cells hyaline, of textura angularis. Paraphyses 3–6 µm wide (xˉ = 4.2 µm, n = 5), hyaline, septate, longer than asci and embedded in a gelatinous matrix. Asci 126–164 × 8–13 µm (xˉ = 145.7 × 10. 2 µm, n = 20), 8-spored, unitunicate, cylindrical, with short pedicel, apically rounded, with a J+, discoid, apical ring. Ascospores 18–22 × 5–7 µm (xˉ = 20 × 6 µm, n = 20), uniseriate, cylindrical to oblong, hyaline when immature, turning subhyaline to brown at maturity, 1-septate, slightly constricted at the septum, guttulate, smooth-walled, lacking a sheath in Indian ink. Asexual morph: Not observed.

Thailand • Chiang Rai Province, Mae Fah Luang University (20°02′42″N, 99°53′41″E), on the dead, decaying twigs of Mimusops elengi (Sapotaceae), 2 October 2023, ZL Tun P3 (holotype MFLU 25-0076).

Thailand • Chiang Rai Province, Mae Fah Luang University (20°02′42″N, 99°53′41″E), on the dead decaying branch of Mimusops elengi (Sapotaceae), 2 October 2023, ZL Tun P3A (MFLU 25-0159).

Amphisphaeria mimusopis is sister to A. flava (MFLU 18-0102) with 100% ML and 1.00 PP bootstrap support (Fig. 1). The interspecies genetic distances between A. mimusopis (MFLU 25-0076) and A. flava (MFLU 18-0102) showed the following base pair differences (without gaps): 1.4% across LSU (13/892 bp) and 6.7% across ITS (37/530 bp). Amphisphaeria mimusopis can be distinguished from A. flava by having larger ascospores (18–22 × 5–7 µm vs 13–16 × 5–7μm) (Samarakoon et al. 2019). Amphisphaeria mimusopis has narrower paraphyses (3–6 µm) than A. flava (7–16.3 µm) (Samarakoon et al. 2019). The ascomata of A. mimusopis produce a pale reddish-brown pigment surrounding the ostioles, whereas A. flava results in a pale-yellow pigmentation on the surface (Samarakoon et al. 2019). Based on morphological and phylogenetic evidence, as well as the recommendations for species delineation by Chethana et al. (2021), we establish Amphisphaeria mimusopis as a new species.

The epithet refers to the host genus, Paraserianthes, from which the fungus was isolated.

MFLU 25-0075.

Saprobic on decaying twigs of Paraserianthes lophantha. Sexual morph: Ascomata 430–520 µm wide, 290–400 µm high (xˉ = 497 × 355 µm, n = 5), immersed, solitary or grouped, scattered, globose to subglobose, dark brown to black, ostiolate. Ostiole central, comprising a short papilla, with an ostiolar canal lined with hyaline periphyses. Peridium 16–20 µm (xˉ = 16 µm, n = 5) two-layered; outer layer wide, dark brown, thick-walled cells of textura angularis, inner layer comprising one layer of pale yellow or sub-hyaline to hyaline cells of textura angularis, thin-walled. Paraphyses 3–5 µm wide (xˉ = 4.5 µm, n = 5), hyaline, filiform, septate, guttulate, longer than asci. Asci 85–152 × 7.5–16 µm (xˉ = 125.5 × 10.5 µm, n = 20), 8-spored, unitunicate, cylindrical, thin-walled, short-pedicellate, apically rounded, with a J+, conspicuous, discoid, apical ring. Ascospores 16–20 × 5–9 µm (xˉ = 19 × 6.9 µm, n = 20), uniseriate, oblong to ellipsoid, hyaline when young, turning yellow brown at maturity, 3-septate, rounded to obtuse ends, smooth-walled, guttulate, without a sheath. Asexual morph: Not observed.

Thailand • Chiang Mai Province, in the forests around the Mushroom Research Center (19°07.200'N, 98°44.044'E), on fallen decaying twigs of Paraserianthes lophantha (Fabaceae), 14 November 2022, Zaw Lin Tun M14, (holotype MFLU 25-0075).

Amphisphaeria paraserianthis (MFLU 25-0075) formed a distinct lineage that is basal to A. neoaquatica (MFLUCC 14-0045) and A. hongheensis (GMB1135) (Fig. 1). The interspecies genetic distances between A. paraserianthis and A. neoaquatica (MFLUCC 14-0045) showed the following base pair differences (without gaps): 7% for LSU (58/818 bp) and 5.11% for ITS (25/489 bp). Amphisphaeria paraserianthis and A. hongheensis (GMB1135) showed the following base pair differences (without gaps): 2.8% for LSU (26/923 bp) and 7.7% for ITS (35/455 bp). The ascomata of A. paraserianthis (430–520 × 290–400 µm) are larger than those of A. neoaquatica (250–320 × 300–330 μm) and smaller than those of A. hongheensis (430–750 × 360–640 μm). The asci of A. paraserianthis (85–152 × 7.5–16 µm) are larger than those of A. neoaquatica (126–138 µm × 8–10 μm), and smaller than A. hongheensis (175−265 × 10–15 µm) (Luo et al. 2019, Liu et al. 2024a). The ascospores of A. paraserianthis (16–20 × 5–9 µm) are larger than A. neoaquatica (15–17 × 5–7 μm) and smaller than A. hongheensis (20−40 × 5−11μm) µm (Luo et al. 2019, Liu et al. 2024a). In addition, A. paraserianthis possesses 3-septate ascospores while A. neoaquatica and A. hongheensis possess 1-septate ascospores (Luo et al. 2019, Liu et al. 2024a). Based on the species delineation suggestions made by Chethana et al. (2021) and the findings from morpho-phylogenetic analyses, we establish A. paraserianthis (MFLU 25-0075) as a new species.

Refers to the morphological similarity with Amphisphaeria micheliae.

MFLU 25-0074.

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.

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 E15 (holotype MFLU 25-0074).

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 (MFLU25-0074) 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.

The epithet refers to the host genus Pterocarpus, from which the fungus was isolated.

MFLU 25-0073.

Saprobic on recently dead branches of Pterocarpus sp. Sexual morph. Ascomata 225–237 μm high, 355–373 µm wide, (xˉ = 231 × 360 µm, n = 5), immersed, visible as black spots, host tissue becoming reddish around the apical pores, solitary to aggregated, scattered, globose to sub-globose, brown. Ostiole central, 70–60 wide, comprising a short papilla. Peridium 12–16 µm wide (xˉ = 14 µm, n = 5), two-layered; outer layer wide, dark brown, thick-walled cells of textura angularis, inner layer comprising one layer of hyaline cells of textura angularis, thin-walled. Paraphyses 4–6 µm wide (xˉ = 4.8 µm, n = 5), hyaline, septate, guttulate, embedded in a gelatinous matrix. Asci 95–116 × 9–14 µm (xˉ = 106 × 11 µm, n = 20), 8-spored, unitunicate, cylindrical, deliquescing, with short pedicel, apically rounded, with a J+, wedge-shaped, apical ring. Ascospores 19–21 × 5–7 µm (xˉ = 20 × 6 µm, n = 20), ellipsoidal, hyaline when immature, turning yellow to yellowish-brown when mature, 3-septate, guttulate, smooth-walled, surrounded by a mucilaginous sheath. Asexual morph: Not observed.

Colonies on MEA reaching 4 cm diam. after 15 days at 27 °C, from above white, dense, irregular, flattened with smooth surface, with lobate margin; reverse yellow red in the middle, yellow at the margin.

Thailand • Chiang Rai Province, Mae Fah Luang University premises (20°02′42″N, 99°53′41″E), on recently dead branches of Pterocarpus rotundifolius (Fabaceae), 06 November 2023, Zaw Lin Tun H62 (holotype MFLU 25-0073), ex-type culture MFLUCC 25-0195.

Thailand • Chiang Rai Province, Mae Fah Luang University premises (20°02′42″N, 99°53′41″E), on dead branches of Pterocarpus rotundifolius (Fabaceae), 06 November 2023, Zaw Lin Tun 2H62 (MFLU 25-0072).

Based on our phylogenetic analyses, A. pterocarpi formed a separate lineage, sister to A. curvaticonidia (MFLUCC 18-0620, HKAS 102288), with 100% ML and 1.00 PP bootstrap support (Fig. 1). Amphisphaeria pterocarpi can be distinguished from A. curvaticonidia by its smaller ascomata (225–237 × 355–373 µm vs. 320–390 × 360–410 µm), asci (95–116 × 9–14 µm vs. 121–162 × 10.5–17.5 µm), and ascospores (19–21 × 5–7 µm vs. 17–23 × 6–9 µm) (Samarakoon et al. 2020). Additionally, the ascospores of A. pterocarpi are ellipsoidal, whereas A. curvaticonidia have oblong or narrowly fusiform ascospores. The asexual morph of A. curvaticonidia has been documented as coelomycetous in culture, while the asexual morph of A. pterocarpi has yet to be observed in culture (Samarakoon et al. 2020). When considering the base pair differences (without gaps) between A. pterocarpi and A. curvaticonidia (MFLUCC 18-0620, HKAS 102288), 2.5% base pair differences (without gaps) were revealed in LSU (27/1040 bp) and 3.30% base pair differences (without gaps) in ITS (18/545 bp). Due to the distinct morphology and phylogenetic evidence, along with the species delineation guidelines provided by Chethana et al. (2021), we introduce A. pterocarpi as a new species.

The epithet refers to the host genus, Schima, from which the fungus was isolated.

MFLU 25-0070.

Saprobic on decaying twigs of Schima wallichii. Sexual morph: Ascomata 480–620 μm high × 520–683 µm wide, (xˉ = 531 × 583 µm, n = 5), immersed with ostiole breaking through host surface, visible as black spot, solitary to aggregated, scattered, globose to subglobose, brown, ostiolate. Ostiole central, comprising a short papilla, with an ostiolar canal. Peridium 13–16 µm wide (xˉ = 14.2 µm, n = 5), two-layered; outer layer thick, dense, reddish-brown cells of textura angularis, inner layer thin, hyaline cells of textura angularis. Paraphyses 3–5 µm wide, hyaline, filiform, septate, embedded in a gelatinous matrix. Asci 196–275 × 21–30 µm (xˉ = 236.2 × 22.9 µm, n = 20), 8-spored, unitunicate, cylindrical, with short pedicel, apically rounded, with J-, apical ring. Ascospores 36.9–40 × 13.5–15 µm (xˉ = 38.6 × 14 µm, n = 20), uniseriate, broadly fusiform, hyaline, turning olivaceous brown to brown at maturity, one median and constricted euseptum, with two distosepta, guttulate (especially at immaturity), broad to conically rounded at both ends, smooth, surrounded by a thick mucilaginous sheath. Asexual morph: Not observed.

Colonies on MEA slow-growing, reaching 3 cm in diam. after 15 days at 27 °C, from above white to pale yellow radiating outwards, dense, circular, irregular, flattened with smooth surface, with lobate margin; reverse yellow brown in the middle, white at the margin.

Thailand • Chiang Mai Province, in forests around the Mushroom Research Center (19°07.200'N, 98°44.044'E), on fallen dead twigs of Schima wallichii (Theaceae), 14 November 2022, Zaw Lin Tun C1 (holotype MFLU 25-0070), ex-type culture MFLUCC 25-0196.

Thailand • Chiang Mai Province, in forests around the Mushroom Research Center (19°07.200'N, 98°44.044'E), on fallen dead twigs of Schima wallichii (Theaceae), 14 November 2022, Zaw Lin Tun C2 (MFLU 25-0071).

Based on our phylogenetic analyses, Amphisphaeria schimae (MFLU 25-0071, MFLUCC 25-0196) is sister to A. ailaoshanensis (KUNCC 23-15520, KUNCC 23-15521) (Fig. 1). However, A. schimae can be distinguished from A. ailaoshanensis by having larger ascomata (480–620 μm high × 520–683 μm vs. 100–140 μm high × 250–350 μm), asci (196–275 × 21–30 μm vs. 70–100 × 7–10 μm), and ascospores (36.9–40 × 13.5–15 μm vs. 14–20 × 5–8 μm) (Dissanayake et al. 2024). Additionally, the ascospores of A. schimae are broadly fusiform, hyaline, turning olivaceous brown to brown at maturity, with one median, conspicuously constricted euseptum, and surrounded by a thick mucilaginous sheath, whereas those of A. ailaoshanensis are fusiform, hyaline, guttulate, turning brown, 1–3-septate, and lack a mucilaginous sheath (Dissanayake et al. 2024). When comparing base pair differences (excluding gaps) between A. schimae (MFLUCC 25-0196) and A. ailaoshanensis (KUNCC 23-15520, KUNCC 23-15521), there is a 4.9% divergence in the LSU region (34/690 bp) and 8.2% divergence in the ITS region (43/525 bp). Based on the distinct morphological and phylogenetic evidence, along with the species delineation guidelines proposed by Chethana et al. (2021), we describe A. schimae as a new species.