Amphibambusa hyalinospora L. S. Dissan. & Wanas. 2026, sp. nov.

Amphibambusa hyalinospora L. S. Dissan. & Wanas. sp. nov. Fig. 2 Etymology. The specific epithet refers to the hyaline ascospores. Holotype. HKAS 149994. Description. Saprobic on the surface of decaying bamboo culms. Sexual morph. Ascomata 590–670 × 400–500 μm (x ̄ = 645 × 467 μm, n = 10), solitary, scattered, immersed under the host epidermis, visible as black pointed spots on the host surface, coriaceous, ostiole at the center. Peridium 25–35 μm (x ̄ = 30 μm, n = 10), multi-layered, outer layer comprising blackish-brown, composed of thick-walled cells of textura angularis, inner layer composed of pale brown to hyaline, thin-walled cells of textura angularis, tightly arranged. Paraphyses 5–9 μm (x ̄ = 6.9 μm, n = 20) wide, intermingled among asci, cylindrical, septate, thin-wall, hyaline, guttulate. Asci 180–260 × 13–20 μm (x ̄ = 222 × 17.2 μm, n = 20), 8 - spored, unitunicate, cylindrical to elongate fusiform, wider in the middle, tapering towards both ends, with rounded end, short-pedicellate, J + apical ring in Melzer’s reagent. Ascospores 80–110 × 6–10 μm (x ̄ = 95 × 8 μm, n = 20), overlapping, 1–2 seriate, hyaline, fusiform, 1 - septate at the center, pointed at both ends, with hyaline round spots when mature, with longitudinal striation along the entire length of the ascospore, with thin-gelatinous sheath. Asexual morph. Unknown. Culture characters. Colonies on PDA, reaching 25–30 mm diameter after one week at 25 ° C, white, cottony flat, low, dense, with uneven margin. Reverse yellowish-brown at the center and yellowish-white edges. Material examined. • China, Yunnan Province, Xishuangbanna, Yinchang Mountain (21.968333°N, 101.1975°E, 1188 m a. s. l.), on dead culm of bamboo, 16 February 2023, L. S. Dissanayake, XTBGYCM 23-06 (HKAS 149994, holotype), ex-type KUNCC 23-15547. ibid. XTBGYCM 23-06 A (HKAS 149995, isotype), ex-isotype, KUNCC 23-15548. Note. Phylogenetic analyses based on multi-locus sequence data reveal that Am. hyalinospora is closely related to Am. bambusicola (GMB 5602: ex-type, GMB 5608 and MFLUCC 11-0617), with 95 % MLBP and 0.97 BYPP support values (Fig. 1). Amphibambusa hyalinospora distinguish from Am. bambusicola having comparatively longer ascospores (95 × 8 μm), constricted at the septum with thin sheath while Am. bambusicola has shorter ascospores (26.6 × 5.7 μm) that are deeply constricted at the septum with thick gelatinous sheath (10 μm) (Liu et al. 2025). A comparison of nucleotide differences (without gaps) between these two species showed 14 / 451 (3.1 %) differences in the ITS region and 9 / 848 (1.06 %) differences in the LSU region. Thus, the combined phylogenetic, morphological and sequence divergence evidence supports recognition of Amphibambusa hyalinospora as a distinct species closely related to Am. bambusicola.