Seiridium vernicola W.L. Li & Jian K. Liu, in Li, Dissanayake, Zhang, Maharachchikumbura & Liu, Journal of Fungi 8(11, no. 1175): 24 (2022)

Index Fungorum number: IF 845411; MycoBank number: MB 845411; Facesoffungi number: FoF 12751.

Etymology – Name reflects the host plant genus it was isolated from, Vernicia

Holotype – HKAS 123221

Pathogenic on diseased branches of Vernicia fordii. Hemsl. Sexual morph: Not observed. Asexual morph: Conidiomata 145–192 μm high, 279–416 μm diam. (x̄ = 169 × 347 μm, n = 15), sporodochial, mostly solitary, immersed to erumpent from tissue, unilocular, conical or cupulate with flattened base, black. Conidiomata wall 48–64.5 μm thick at sides, not well defined, comprising brown thin-walled cells of textura angularis, with lighter cells at the base fusing into the host tissue. Conidiophores septate, cylindrical, irregularly branched, branch lengths variable (33–64 μm long), hyaline or paler brown, thin- and smooth-walled. Conidiogenous cells 5.5–10 × 2–3 μm (x̄ = 8 × 2.5 μm, n = 30), discrete, hyaline, cylindrical, smooth- and thin-walled. Conidia 25–32 × 8–10 μm (x̄ = 28 × 9 μm, n = 30), lunate to falcate, curved, 5-septate, rarely 4- or 6-septate, not striate, bearing one appendage, euseptate with no visible pores, basal cell obconic with a truncate base, hyaline, smooth-walled, 4–5 μm long; four median cells, 18–25 μm long, smooth, cylindrical to doliiform, brown to dark brown, and septa darker than the rest of the cells, second cell from base 4–5 μm long, third cell 4.5–6.5 μm long, fourth cell 4–5.5 μm long, fifth cell 4.5–6.5 μm long, apical cell conical, hyaline, smooth, 3–4.5 μm long, apical appendage single, mostly excentric, 2.5–5 μm long, basal appendage 1–1.5 μm long, mean conidium length/width ratio = 3:1.

Culture characteristics – Colonies on PDA reaching 20 mm diam. after 2 weeks at 25 ℃. Cultures from above, cream with white, dense, circular, umbonate, papillate with fluffy, covered with white aerial mycelium.

Material examined – CHINA, Sichuan Province, Guangyuan city, on a diseased branch of Vernicia fordii, 19 April 2021, W.L. Li, YT 183 (HKAS 123221, holotype), ex-type living culture, CGMCC3.23560; Chengdu city, on a diseased branch of Sapium sebiferum, 5 March 2021, T. Zhang, A6 (HUEST 22.0050, paratype), living culture UESTCC 22.0049; ibid., A10 (HUEST 22.0051, paratype), living culture UESTCC 22.0050.

Notes – Three strains of Seiridium vernicola forms a distinct clade in the multi-locus phylogenetic tree. Seiridium vernicola is morphologically similar to the type species of Seiridium (S. marginatum) and S. venetum in having hyaline, cylindrical and relatively long conidiophores, but S. marginatum differs from S. vernicola in its longer conidia (38–42 μm vs. 25–32 μm) and well-developed appendages (apical appendage: 3.5–7.5 μm vs. 2.5–5 μm; basal appendages: 1.5–5.5 vs. 1–1.5 μm). In addition, conidia of S. marginatum have striate surface, which is not observed in those of S. vernicola. Seiridium venetum differs from S. vernicola in having narrower conidia (6.5–8.5 μm vs. 8–10 μm) with branched appendages.

Figure 7 – Seiridium vernicola (HKAS 123221, holotype). a–c Appearance of conidiomata on the host. d vertical section of conidiomata. e, f Sporodochia. g–j Conidiophore and conidia. k–l Conidiogenous cells and conidia. m–p Conidia. q Germinating conidium. r, s Upper and reverse view of the colony (on PDA). Scale bars: d = 100 μm, e = 20 μm, f–q = 10 μm