Helminthosporium velutinum Link
Index Fungorum number: IF 250075; Facesoffungi number: FoF 01053
Saprobic on submerged decaying wood in freshwater habitats. Sexual morph: Undetermined. Asexual morph: Colonies saprobic, dark brown, effuse, velvety. Mycelium immersed, composed of branched, septate, thick-walled hyphae. Conidiophores mononematous, macronematous, mostly unbranched, proliferating, dark brown, 530–655 μm long (x̄ = 594 μm, SD = 62, n = 10), 16–18 μm wide (x̄ = 17 μm, SD = 1, n = 10), 17–23-septate, erect or flexuous, tapering towards apex, bulbous at base with cells near apex of conidiophore guttulate and fertile. Conidiogenous cells polytretic integrated, intercalary and terminal. Conidia 67–79 μm long (x̄ = 73 μm, SD = 6, n = 20), 15–19 μm wide (x̄ = 17 μm, SD = 2, n = 20), single, obclavate, pale brown to brown, 7–9-distoseptate, smooth, straight or curved, base slightly truncate, cicatrized and wider than apex, dark brown, apical cell paler than other cells, rounded at apex, guttulate when young, non-guttulate at maturity. Conidial secession schizolytic. (Descriptions from Zhu et al. 2016)
Material examined: CHINA, Yunnan Province, Dali, WanHua stream, saprobic on decaying wood submerged in stream, July 2014, Qin-yan Li, 2WHXM H 1–1 (S-135), (HKAS 84015, reference specimen designated here), living culture MFLUCC 15–0428 =KUMCC; ibid., Linquan stream, saprobic on decaying wood submerged in stream, March 2014, Hong-yan Su, LQXM 19–4 (S-033), HKAS 83990, culture MFLUCC 15–0423 = KUMCC; ibid. Heilong stream, saprobic on decaying wood submerged in stream, March 2014, Xiao-ying Liu, HLXM 45–1 (S-076), HKAS 84000, living culture MFLUCC 15–0243 =KUMCC.
Notes: Helminthosporium velutinum is found on a wide range of dead plant material and it is considered to be a cosmopolitan taxon. Based on a megablast search of NCBIs GenBank nucleotide database the closest hits using the ITS sequence data of the isolate S-135 are Helminthosporium velutinum strain 1-05 (GenBank JF502424; identities = 455/455(100%), gaps = 0/455(0%), H. velutinum (GenBank JN19843; identities = 455/456(99%), gaps = 1/456(0%)) and H. velutinum strain ATCC38969 (GenBankAF120262; identities = 454/455(99%), gaps = 0/455(0%)) and H. velutinum strain CBS 360.75 (GenBankAF145704; identities = 452/455(99%), gaps = 0/455(0%)). Based on morphology, and the similarity of the ITS sequences available from various collections worldwide, we recognize our isolates as being H. velutinum. Being primarily associated with dead plant material in terrestrial ecosystems, the fungus might have been introduced to the streams from the neighboring riparian terrestrial environment. (Notes from Zhu et al. 2016)