Kirschsteiniothelia guangdongensis Senan. & K.D. Hyde, sp. nov.

Index Fungorum number: IF 900339; MycoBank number: MB 900339; Facesoffungi number: FoF 14167; Fig. 1

Etymology – based on the region where sample has been collected.

Saprobic on dead branches of unidentified plant. Sexual morph: Undetermined. Asexual morph: Colonies on natural substrate, superficial, hairy, black, scattered, single or in groups, with superficial, dark brown to black hyphae. Conidiophores 250–350 μm long, 10–18 μm wide, superficial on host surface, macronematous, mononematous, simple, erect to slightly flexuous, unbranched, septate, not constricted at the septa, dark brown, cylindrical. Conidiogenous cells 15–18 × 9–12 μm (x=17 × 10 μm, n=20), monoblastic, integrated, percurrently proliferating, terminal, cylindrical to ampulliform, determinate, dark brown. Conidia 290–300 μm long, 42–50 μm wide at base, 20–22 μm wide at apex, elongated, flask-shaped, straight or slightly curved, rounded at the apex, apical cell paler than others, 13 transverse septa with one longitudinal septum in 5 basal cells, a thin sheath at apex extend up to 3rd cell from the top, blackish brown to black, thin-walled, smooth; secession by schizolysis or rhexolysis.

Culture characters – Colonies on PDA reached 4 cm diam., after 7 days incubated in dark at 25 °C; circular, flat, filiform margin, with moderate aerial mycelia, surface view blackish green with grey aerial mycelia, reserve olivaceous grey.

Material examined – China, Guangdong Province, Guangzhou, Haizhu District, (23° 06′ 28.4″ N 113° 16′ 51.7″ E), on twigs of unidentified plant, 18 June 2021, Kularathnage N.D., NDK 19–2, (MHZU 22-0137, holotype), ex-type culture ZHKUCC 22-0233.

GenBank numbers – ITS: OR164946, LSU: OR164974.

Notes – The combined ITS, LSU and SSU gene analysis (Fig. 2) showed that our collection (MHZU 22-0137) is phylogenetically close to Kirschsteiniothelia tectonae forming a distinct clade with ML/BI=98/1.00 bootstrap support. The nucleotide differences in ITS and LSU sequences of our collection and Kirschsteiniothelia tectonae revealed 2.96% and 5.82% respectively. Our collection morphologically differs from Kirschsteiniothelia tectonae by its flask-shaped, elongated, thin-walled highly pigmented conidia with 13 transverse septa and one longitudinal septum in five basal cells, large conidiophores and conidiogenous cells while K. tectonae has small (x=137×16 μm), cylindric-obclavate, dark reddish-brown, thick-walled conidia with 9–25 or more transverse septa (Li et al. 2016). It should be noted that, the characters of Kirschsteiniothelia tectonae were described from sporulating cultures while the characters of our collection were obtained from the substrate. Therefore, based on morphology, and phylogeny, we describe our collection as Kirschsteiniothelia guangdongensis.

Figure 1 – Kirschsteiniothelia guangdongensis (MHZU 22-0137, holotype). a Colonies on natural substrate. b, c Conidiophores with conidia. d, e Conidia. f Surface view of colony. g Reserve view of colony. h–l Conidia of Kirschsteiniothelia tectonae (MFLUCC 12-0050). Scale bars: b–e=150 μm

Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, LSU and SSU sequence data which comprised 1801 characters (ITS=590, LSU=876, SSU=1035). The best scoring RAxML tree with a final likelihood value of − 17,128.646756 is presented. The matrix had 1148 distinct alignment patterns, with 36.37% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.237038, C=0.247650, G=0.281313, T=0.233999; substitution rates: AC=1.304030, AG=2.746538, AT=0.938119, CG=1.489864, CT=5.666453, GT=1.0; gamma distribution shape parameter α=0.518282. Bootstrap support for maximum likelihood (ML) equal to or greater than 50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. The tree is rooted to Astrosphaeriella bakeriana (MFLUCC 11-0027, CBS 115556)