Melomastia maolanensis Norphoun, T. C. Wen & K. D. Hyde

Melomastia maolanensis (Jin F. Zhang, Jian K. Liu, K. D. Hyde & Zuo Y. Liu) Norphoun, T. C. Wen & K. D. Hyde, Cryptog. Mycol. 38 (4): 518 (2017) Fig. 6 Description. Saprobic on dead stems of Chromolaena odorata. Sexual morph: Ascomata 420–440 µm high (including ostiole), 330–365 µm diam. (x – = 426 × 351.3 µm, n = 5), visible as dark, raised, black spots on host, scattered, solitary to gregarious, immersed, with erumpent ostiole, perithecial, subglobose to obpyriform, coriaceous, dark brown to black, papillate, with a black clypeus. Ostiole 170–190 × 160–190 µm, central, oblong, dark brown to black, periphysate. Peridium 18–25 µm wide, comprising two layers; outer layer made up of thick-walled, dark brown cells fusing with host tissue, inner layer composed of thin-walled, hyaline cells. Pseudoparaphyses 1.5–3 µm wide, numerous, filiform, generally aseptate and unbranched, tapering towards the apex. Asci 80–125 × 4–7 µm (x – = 102.7 × 5.5 µm, n = 20), 8 - spored, non fissitunicate, long cylindrical, slightly flexuous, short-pedicellate, truncate or rounded at the apex, with a small ocular chamber. Ascospores 14–18.5 × 3–5 µm (x – = 17.2 × 4.2 µm, n = 20), uniseriate, partially overlapping, hyaline, fusiform, with rounded or acute ends, 3 - septate, constricted at the septa, smooth-walled, guttulate, surrounded by a mucilaginous sheath which vanishes with age. Asexual morph: Not observed. Material examined. Thailand • Chiang Mai, on dead stems of Chromolaena odorata, 7 Jul 2021, N. S. Wijesinghe CMN 1, Herbarium material MFLU 23-0143. Notes. In this study, strain MFLU 23-0143 clustered with M. maolanensis (GZCC 16-0102) with 100 % ML BS, 1.00 BYPP support in the multi-locus phylogeny (Fig. 3). Nucleotide comparison of LSU and tef 1 - α revealed 0.1 % (1 / 911 bp) and 1.3 % (12 / 921 bp) differences between the two strains (MFLU 23-0143 and GZCC 16-0102), indicating insufficient phylogenetic differences to separate them as two different taxa (Jeewon and Hyde 2016; Maharachchikumbura et al. 2021). The two strains are also morphologically similar with ostiolate and papillate, immersed ascomata, long cylindrical and short-pedicellate asci, and ascospores that are fusiform, guttulate, and 3 - septate. Therefore, strain MFLU 23-0143 is identified as M. maolanensis based on morphological and phylogenetic evidence. The main morphological difference between the two strains is the presence of a mucilaginous sheath around the ascospores of M. maolanensis MFLU 23-0143, while no such report was made for the strain GZCC 16-0102 (Zhang et al. 2017). Variations in the size of the morphological characteristics between the two strains may be accounted for by environmental differences. Zhang et al. (2017) reported M. maolanensis from an undetermined tree branch in China. The same taxon is reported here from dead stems of Chromolaena odorata in Thailand.