Ophiosphaerella aquaticus Z.L. Luo, H.Y. Su & K.D. Hyde.
Index Fungorum number: IF551441; Facesoffungi number: FoF00951; Fig. 1
Etymology – With reference to the aquatic habitat.
Holotype – MFLU 15–0071

Saprobic on decaying wood submerged in freshwater. Sexual morph: Ascomata 420 – 470 μm high, 265 – 360 μm diam., scattered, solitary, immersed to semi – immersed or erumpent through host tissue, with minute papilla, visible as raised, small black dots on host surface, uni – loculate, pyriform, pilous, dark brown to black, ostiole central, with periphyses. Peridium 20 – 37 μm wide, of unequal thickness, composed of several layers of pseudoparenchymatous cells, outer part comprising dark brown, occluded thickened cells, fusing with the host, inner part comprising several layers of thin-walled, flattened, brown-walled cells. Hamathecium composed of numerous, 3 – 6 μm wide, filamentous, septate pseudoparaphyses, embedded in a mucilaginous matrix, anastomosing at the apex. Asci 146 – 174 × 10 – 12.5 μm (x̄ = 160 × 11 μm, n = 20), 8 – spored, bitunicate, cylindrical to cylindric – clavate, short pedicellate, apically rounded, with an ocular chamber. Ascospores 143 – 162 × 2.5 – 3.5 μm (x̄ = 152.5 × 3 μm, n = 20), fasciculate, scolecosporous, parallel or spiral, filiform, pale brown to brown, aseptate, smooth – walled. Asexual morph: Undertermined.

Material examined – THAILAND, Chiang Mai Province, saprobic on decaying wood submerged in a stream, November 2013, Z.L. Luo ZL-4 (MFLU 15–0071, holotype), ex-type culture, MFLUCC 14-0033, KIBCC, DLUCC; ibid. (HKAS 86446, isotype).

Notes – This scolecosporous Ophiosphaerella species was collected from a decaying stem of bamboo submerged in freshwater in Thailand. Ophiosphaerella aquaticus is characterized by semi – immersed, ascomata with a central ostiole, and filiform ascospores. In the phylogenetic analysis, O. aquaticus clusters with O. agrostidis in the family Phaeosphaeriaceae but in a distinct clades. Ophisphaerella aquaticus is compatible with O. agrostidis. However, O. aquaticus differs in having a pyriform ascomata, larger aseptate ascospores and in its aquatic habit (Phookamsak et al. 2014).

Fig. 1 Ophiosphaerella aquaticus (holotype). a Host specimen b Ascomata on submerged wood c Section of ascoma d, e Section through peridium f Pseudoparaphyses g – i Asci j – k Ascospores l Germinating ascospore. Scale bars: c = 150 μm, d = 50 μm, e – f = 30 μm, g – l = 50 μm.