Pleurotheciella hyalospora J. Ma & Y.Z. Lu, sp. nov.

Index Fungorum number: IF 900171; Mycobank number: MB 900171; Facesoffungi number: FoF 13906; Fig. 1

Etymology – “hyalospora” referring to the hyaline conidia.

Holotype – GZAAS 22–2018.

Saprobic on decaying wood. Sexual morph: undetermined. Asexual morph: Colonies on the substratum superficial, effuse, gregarious, white. Mycelium composed of partly immersed, partly superficial, hyaline to pale brown, septate, branched hyphae, with a little of glistening conidia. Conidiophores macronematous, mononematous, unbranched, straight or flexous, cylindrical, 73–100 × 3.5–5 μm (x = 88×4 μm, n=20), dark brown at the base, hyaline to pale brown toward the apex, smooth-walled. Conidiogenous cells polyblastic, terminal, cylindrical, 17–30 × 3–4 μm (x = 25×3.5 μm, n=20), with denticles, pale brown near base, hyaline towards apex, smooth-walled. Conidia solitary, acropleurogenous, fusoid or clavate, slightly curved, rounded at the apex, obtuse and tapering towards base, 11–20×3–5.5 μm (x = 16×4.5 μm, n=30), hyaline, 1-septate, often with 1–3 guttules in each cell, smooth-walled.

Culture characteristics – Conidia germinating on water agar and germ tubes produced from conidia within 8 h. Colonies growing on PDA, circular, with flat surface and filiform margin, reaching 35 mm in 30 days at 25 °C, brown in center, pale brown at the entire margin.

Material examined – China, Guizhou Province, Guiyang City, Xiaochehe Park, on decaying wood in a forest, 29 March 2020, Jian Ma, XCH20 (GZAAS 22–2018, holotype), ex-type living culture, GZCC 22–2018; Guizhou Province, Longli County, on decaying wood submerged in a freshwater stream, 3 December 2020, Jian Ma, LLSZ2 (GZAAS 22–2023), living culture, GZCC 22–2023.

GenBank numbers – GZCC 22–2018: LSU=OQ002371, ITS= OQ002374, SSU = OQ002377, RPB2= OP999221; GZCC 22–2023: LSU = OQ002370, ITS = OQ002373, SSU=OQ002376, RPB2=OP999220.

Notes – The proposed new species viz. Pleurotheciella hyalospora is morphologically similar to P. uniseptata in conidiophores and conidia, but it can be recognized from P. uniseptata by having smaller conidiophores (73–100×3.5–5 μm vs. 100–150×4.5–5 μm). Besides, the conidia of P. hyalospora are slightly curved, while P. uniseptata is characterized by straight conidia (Réblová et al. 2016). Phylogenetically, P. hyalospora forms a sister clade to P. uniseptata and the phylogentic tree showed that they are distinct species (Fig. 2).

Figure 1 – Pleurotheciella hyalospora (GZAAS 22–2018, holotype). a, b Colonies on decaying wood. c, d Conidiophores. e–h conidiogenous cells with attached conidia. i Germinated conidia. j–m Conidia. n, o Colony on PDA from above and below. Scale bars: c–m=10 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU, SSU and rpb2 sequence data representing the species of pleurotheciaceae. Thirty-nine taxa were included in the combined analyses, which comprised 3393 characters (ITS: 621, LSU: 870, SSU=986, rpb2=916) after alignment. Bootstrap support values for ML equal to or greater than 50% and BYPP equal to or greater than 0.95 are given above the nodes. Conioscypha minutispora (CBS 137253) and C. tenebrosa (GZCC 19-0217) were used as the outgroup taxa. The newly-generated strain is shown in blue and bold. Ex-type strains are indicated by black and bold