Kirschsteiniothelia crustaceum S. Wang, Q. Zhao & K.D. Hyde sp. nov. 

Index Fungorum number: IF559760; MycoBank number: MB 559760; Facesoffungi number: FoF 11802; Fig. 1

Etymology – Referring to the conidial ‘shell’ shape.

Holotype – MFLU 21-0129

Saprobicon decaying bamboo culms. Sexual morph: Not observed. Asexual morph: Colonies effuse, scattered, dark brown to black, glistening, hairy, sparse. Mycelium partly superficial, partly immersed in the substratum, composed of dark brown, septate, branched hyphae. Conidiophores macronematous, mononematous, solitary, cylindrical, straight or slightly flexuous, brown to dark brown, slightly tapering towards the apex, 4–8 septate, truncate at the apex, 60–170 µm (x̄ = 128 µm, n = 15) long, 6.5–10.5 μm (x̄ =8 µm, n = 15) wide. Conidiogenous cells integrated, terminal, monoblastic, cylindrical and calyciform, brown, 9–16 µm (x̄ = 12 µm, n = 15) long, 5.5–8 μm (x̄ =6.5 µm, n = 15) wide. Conidia acrogenous, solitary, obclavate to obspathulate, globose to the apex and hyaline to light brown, rostrate, 5–6-euseptate, mid to dark brown, becoming pale brown to pale towards the apex, truncate at the base, 45–75 µm (x̄ = 55 µm, n = 20) long, 10–18 μm (x̄ = 14 µm, n = 20) wide.

Material examined – Thailand, Nang Lae, Mueang Chiang Rai, Chiang Rai Province, saprobic on decaying bamboo, submerged in a freshwater stream, July 2020, Rongju Xu, MD71 (MFLU 21–0129, holotype)

GenBank numbers – MW851854 (LSU); MW851849 (ITS)

Notes – Kirschsteiniothelia crustaceum shares similar morphology with K. rostrata in having macronematous, unbranched, cylindrical, septate, conidiophores and solitary, obclavate, septate, conidia. However, conidiophores of Kirschsteiniothelia crustaceum (60–170×6.5–10.5 μm) are much shorter than those of K. rostrata (up to 280 μm long, 12 μm wide). Conidia of K. crustaceum (45–75×10–18 μm) are much shorter than those of K. rostrata (up to 115 μm long, 15 μm wide) also. The combined LSU, SSU and ITS phylogenetic analysis show that Kirschsteiniothelia crustaceum represents a sister taxon to K. rostrata with good separation (89ML/1.00BYPP) (Fig. 2).

Figure 1 – Kirschsteiniothelia crustaceum (MFLU 21–0129 , holotype) a,b Colonies on dead wood. c Conidiophore with conidia. d–g Conidiogenous cells and conidia. h–k Conidia. l Germinating conidium. m Culture on MEA Scale bars: b –e = 50 μm, f = 20 μm, g = 50 μm, h –l = 20 μm.

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, ITS sequence data. Forty-six taxa were included in the combined analyses, which comprised 2,104 characters (LSU=1–788 bp, SSU=789–1,632 bp, ITS=1,633–2,104 bp), including alignment gaps. Among them, 1,191 characters were constant, 239 characters were singleton sites, and 674 characters were parsimony informative. The best scoring RA×ML tree is presented. Bootstrap support values for ML and MP≥75% and BYPP≥0.95 are given above the nodes. Pseudorobillarda eucalypti (MFLUCC 12–0422) and P. phragmitis (CBS 398.61) were used as the outgroup taxa. The newly generated sequences are indicated in red. The ex-type strains are indicated in bold