Aquihelicascus thalassioideus (K.D. Hyde & Aptroot) W. Dong & H. Zhang
Index Fungorum number: IF557920; Facesoffungi number: FoF09262
Basionym: Massarina thalassioidea K.D. Hyde & Aptroot, Nova Hedwigia 66(3–4): 498 (1998)
Synonymy: Helicascus thalassioideus (K.D. Hyde & Aptroot) H. Zhang & K.D. Hyde, Sydowia 65(1): 159 (2013)
Saprobic on decaying wood submerged in freshwater. Sexual morph: Pseudostromata clustered, immersed, visible on the host surface as blackened ostiolar dots. Pseudoparaphyses 1–3 μm diam., abundant, cellular, hypha-like, hyaline, septate, embedded in a gelatinous matrix. Asci 150–190 × 14.5–23 μm (x̄ = 175 × 17.5 μm, n = 5), 8-spored, bitunicate, fissitunicate, clavate, long pedicellate, up to 90 μm long. Ascospores 24–28 × 7–10 μm (x̄ = 25.5 × 8.5 μm, n = 25), overlapping uni- to bi-seriate, sometimes overlapping tri-seriate, ellipsoidal, hyaline, 1-septate, constricted at septum, curved, thin-walled, smooth. Asexual morph: Undetermined (detailed description see Hyde and Aptroot (1998) and Zhang et al. (2013).
Material examined: THAILAND, Chiang Rai Province, on submerged wood in a stream, 1 July 2018, W. Dong, CR134-1 (MFLU 18-1705), living culture KUMCC 19-0094; ibid., CR134-2 (HKAS 105076).
Notes: The new collection KUMCC 19-0094 is identified as Aquihelicascus thalassioideus based on multigene phylogenetic analysis. The morphological feature of KUMCC 19-0094 also fits well with A. thalassioideus except for the long pedicel, which is probably because of the pedicel spreading in water. Most publications do not report an ascospore sheath for A. thalassioideus except Zhang et al. (2015) who noted some fugacious mucilaginous remnants visible in Indian Ink when ascospores were just released from the asci. This character was not observed in our collection. (Notes from Dong et al. 2020)
Freshwater distribution: Australia (Hyde and Aptroot 1998), Brunei (Hyde and Aptroot 1998), China (Tsui et al. 2000; Ho et al. 2001; Luo et al. 2004), French West Indies, Martinique (Zhang et al. 2015), Peru (Shearer et al. 2015), Japan (Tanaka et al. 2015), Philippines (Hyde and Aptroot 1998b), Thailand (Kurniawati et al. 2010; Zhang et al. 2013; Dong et al. 2020)