Acrocalymma arengae

Acrocalymma arengae

Konta & K.D. Hyde (2023)

Classification:Ascomycota-Pezizomycotina-Dothideomycetes-Pleosporomycetidae-Pleosporales-Acrocalymmaceae-Acrocalymma

Host species: Arenga pinnata (Konta et al. 2023)

Holotype: MFLU 15-0302 (Konta et al. 2023)

Known distribution: Phang-Nga, Thailand

IF Number: IF559674     Mycobank Number: 559674    FOF Number: FoF10819

Description

Saprobic on dead rachis and petioles of Arenga pinnata. Sexual morph: Ascomata 400–500 × 120–170 μm (x̅ = 455 × 150 μm, n = 10), dark brown sometimes covered with light grey, gnarled, warted hairs/setae, gregarious, immersed beneath host epidermis, not upright, laid on the substrate, visible as numerous, raised, dome-shaped areas on the host surface, obpyriform to ampulliform, uni-loculate, rough walls with setae, coriaceous, ostiolate. Ostioles 200–220 × 60–80 μm (x̅ = 215 × 70 μm, n = 10), centrally located, ostiolar canal filled with hyaline periphyses. Peridium 15–30 µm (x̅ = 23 μm, n = 10) wide, composed of dark red-brown to black cells, arranged in textura globulosa to textura angularis. Pseudoparaphyses 1.5–3 µm (x̅ = 2.1 μm, n = 10) wide, numerous, filamentous, branched, septate. Asci 60–190 × 15–30 μm (x̅ = 115 × 20 μm, n = 30), 1–8-spored, bitunicate, cylindrical to clavate, club-shaped pedicellate, apically rounded with an ocular chamber. Ascospores 25–40 × 5–15 μm (x̅ = 30 × 10 μm, n = 30), overlapping 1–2-seriate, hyaline to pale brown, fusiform with acute ends, 1–3-septate, constricted at the septum, rough-walled, surrounded by a thick mucilaginous sheath. Asexual morph: Undetermined.

Culture conditions: Ascospores germinating on MEA within 12 hr. Colonies on MEA from above, brown to greenish-brown at the centre, creamy white until margin; hyaline mycelia at the entire edge; dense, fluffy, and circular; colonies from below, dark-olivaceous brown at the centre, becoming yellowish-brown, and creamy white towards the edge.