Phialocephala chinensis Senan., N. Yapa & K.D. Hyde, sp. nov.

Index Fungorum number: IF 900436; MycoBank number: MB 900436; Facesoffungi number: FoF 14188; Fig. 1

Etymology – based on the region where the sample was collected.

Saprobic on dead stem of unidentified plant. Sexual morph: Undetermined. Asexual morph: Mycelia 4–5 µm diam., consisting of brown, smooth, thick-walled, branched, septate hyphae sometime slightly constricted at the septa, sometimes 3–5 in bundles. Synanamorphic with diplococcium-like and phialocephala-like (on culture). diplococcium-like synanamorph: Conidiophores 6–8 µm wide, macronematous, erect, solitary or clusters, branched, cylindrical, multiseptate, constricted at the septa, brown, smooth, thick-walled, sometimes with vertical or irigular striations, densely branched at maturity. Conidiogenous cells 5–12.5×2–3.5 µm, phialidic, cylindrical, monoblastic or polyblastic, integrated, terminal or intercalary, extensions sympodial, with 1–2 conidiogenous loci, septate, hyaline, smooth-walled. Conidia 2–4×3–6 µm (x=3.5–5 µm, n=20), globose to oval, unicellular, hyaline, smooth-walled, multiguttulate. Phialocephala-like synanamorph: Synnemata arising on hyphae, erect, unbranched, dark brown, up to 40–60 µm high, conidia produce on upper half of the synnemata. Conidiophores 1–3 µm wide, erect, pale brown, smooth, cylindrical, thick-walled, branched, septate. Conidiogenous cells monoblastic or polyblastic, integrated, terminal or intercalary, extensions sympodial, with single conidiogenous loci. Conidia 2–3×3–5 µm, blastic, globose to oval, hyaline, smooth-walled, unicellular, in chains later separate into single conidia.

Culture characteristics – Colonies on PDA reached 2 cm diam., after 30 days incubated in dark at 25 °C; circular, flat, smooth margin, white, little aerial mycelial clots, becoming brown when mature, dark brown synnemata with white conidial mass visible; reverse pale brown middle with creamy margin.

Material examined – China, Guangdong Province, Shenzhen City, Nanshan District, Yangtai Forest Park Mountain, 22° 39´21.26″ N 113° 57´18.53″ E, decaying stem of unidentified plant, 18 June 2020, I.C. Senanayake, 1026 (MHZU 22-0087, holotype), ex-type cultures ZHKUCC 22-0153, ZHKUCC 22-0157.

Genbank numbers – ITS: OR164942, OR164943, LSU: OR164970, OR164971.

Notes – Combined gene analysis of ITS, LSU and tef1-α showed that our isolates (ZHKUCC 22-0153, ZHKUCC 22-0157) clustered with Phialocephala hiberna (Basionym: Cadophora hiberna Bills) (CBS 110521), but genetically distinct forming a well-supported clade with ML/BI=98%/0.90 statistical support. The base pair difference in ITS locus between our collection and type strain of Phialocephala hiberna is 2.56%. Morphologically, our collection and Phialocephala hiberna are distinct from each other. Phialocephala hiberna forms distinct sporodochium on substrate while our collection forms synnemata. Further, we observed diplococcium-like and phialocephala-like anamorphs (synanamorphs) from our collection. Phialocephala hiberna produce broadly elliptical, pale olive-brown, eguttulate, smaller (2–3.5 × 1.5–2 µm) conidia while our collection produce large, globose, hyaline, sometime guttulate conidia. Therefore, we introduce our collection as a new Phialocephala species, P. chinensis (Fig. 2).

Figure 1 – Phialocephala chinensis (MHZU 22-0087, holotype). a Surface view of culture on PDA. b Reverse view of culture on PDA. d Vegitative hyphae. c, h Synnemata of phialocephala-like synanamorph (on culture). g, i–m Conidia attached to conidiogenous cells. n Conidial chains. e, f Synnemata of diplococcium-like synanamorph (on substrate). g Conidia attached to conidiogenous cells. Scale bars: c=50 µm, d–n=10 µm

Figure 2 – The best scoring RAxML tree with a final likelihood value of − 14,938.532372 for combined dataset of ITS (521 bp), LSU (850 bp) and β-tubulin (588 bp) sequence data. The topology and clade stability of the combined gene analyses was compared to the single gene analyses. The tree is rooted with Leotia lubrica (AFTOL ID 1). The matrix had 1013 distinct alignment patterns with 52.57% undetermined characters and gaps. Estimated base frequencies were as follows; A=0.255331, C=0.228833, G=0.278368, T=0.237468; substitution rates AC=1.157479, AG=2.182775, AT=1.284773, CG=0.936220, CT=5.805724, GT=1.0; gamma distribution shape parameter α=0.333593. Ex-type strains are in bold and newly generated sequences are in red. Bootstrap support for ML equal to or greater than 50% and BYPP equal to or greater than 0.90 are given above the nodes

Figure 2 – (continued)