Sporidesmium pyriformatum J. Yang & K.D. Hyde, sp.nov., Index Fungorum number: IF552227
Etymology: Referring to the pyriform conidia.
Saprobic on submerged wood in a stream. Colonies on substrate superficial, effuse, dark brown, hairy. Mycelium mostly immersed, composed of branched, septate, hyaline to pale brown hyphae. Sexual morph Undetermined. Asexual morph Conidiophores macronematous, mononematous, solitary or caespitose, cylindrical, straight or slightly flexuous, smooth, 2–5-septate, brown, paler towards the apex, 65–190 x 3–5.5 μm (x = 118.5 x 4 μm, n = 20). Conidiogenous cells holoblastic, integrated, lageniform, terminal, brown to olivaceous, 9–24.5 x 4–7 μm, darkened and truncate at the apex, with up to three lageniform percurrently proliferating. Conidia acrogenous, solitary, pyriform or obclavate, 3–4-euseptate, the lower 3–4 cells olivaceous to brown, with pale brown to subhyaline apical cell, darkened at the septa, 18.5–32.5 x 8–15.5 μm (x = 25.5 x 12 μm, n = 20).
Culture characteristics: Conidia germinating on PDA within 24 h. Germ tubes produced from the apex. Colonies on MEA reaching 10–15 mm diam. after 2 weeks at 25 ºC, white in the middle, pale yellow at edge, with dense white mycelium on surface, sparser to the edge; in reverse with a yellow middle with yellowish irregular margin.
Material examined: THAILAND, Prachuap Khiri Khan Province, Hua Hin, stream flowing outside Kaeng Krachan National Park, on submerged wood, 25 December 2014, Jaap van Strien Site4-26-3 (MFLU 15-1155, holotype); extype living culture, MFLUCC15-0620; ibid. (MFLU 15-1162, paratype).
Note: Phylogenetic analysis of combined LSU and ITS sequence data, supports the placement of our taxon within Sporidesmium and reveals a close relationship to S. parvum (S. Hughes) M.B. Ellis and S. fluminicola H.Y. Su & K.D. Hyde. We therefore introduced this as a new species, Sporidesmium pyriformatum. The conidial shape of S. pyriformatum resembles those of S. penzigii Cooke & Ellis, S. jasminicola M.B. Ellis, S. bambusinum N.D. Sharma, S. fraxini-paxianae Jian Ma & X.G. Zhang, S. submersum H.Y. Su & K.D. Hyde, S. parvum and S. fluminicola. However, the conidia of the new taxon are larger than those of S. parvum (18–24 x 8–9 μm), but smaller than those of the other taxa that listed above. Sporidesmium pyriformatum is distinguished from the newly introduced taxa S. submersum and S. fluminicola in having much longer conidiophores and fewer septa (Su et al. 2016a).
Fig. Sporidesmium pyriformatum (MFLU 15-1155, holotype). a Colonies. b–e Fruiting body. f Conidiophores. g, h Conidiogenous cell. i–n Conidia. o Germinated conidia on PDA medium. p, q Culture, p from above, q from below. Scale bars a = 100 μm, b–f, o = 30 μm, g, h = 20 μm, i–n = 10 μm.