Halobyssothecium thailandica 2021

Halobyssothecium thailandica D.F. Bao, Z.L. Luo, K.D. Hyde & H.Y. Su, sp. nov.2021

Index Fungorum number: IF 558523; Facesoffungi number: FoF 09922 

Holotype: MFLU 21–0077

Morphological description:

Sexual morph: : Ascomata 340–490 × 215–345 μm (x = 415 × 280 μm, n = 10), immersed to semi-immersed, gregarious, scattered, carbonaceous, dark brown to black, as dark spots on host surface, ostiolate. Ostioles central, papillate, light brown to dark brown, composed of several layers of pseudoparenchymatous cells. Peridium 16–25 μm wide, comprising two layers, outer layer of brown pseudoparenchyma; inner layers of hyaline to pale brown cells of textura prismatica. Hamathecium comprising 1.5–2.5 μm (n = 30) wide, numerous, branched, septate, hyaline, cellular pseudoparaphyses. Asci 138–160 × 17–21 μm (x = 148 × 18 μm, n = 20), 8-spored, bitunicate, fissitunicate, cylindric-clavate, rounded at apex, with a short pedicellate. Ascospores 39–47 × 8–10 μm (x = 43.3 × 8.9 μm, n = 30), overlapping 2–3-seriate, hyaline when young, light brown to dark brown when mature, cylindric to clavate with round ends, tapering towards the base, straight or slightly curved, 4–7-septate, mostly 7-septate, constricted at the septa, guttulate, smooth-walled, surrounded by a gelatinous sheath.

Asexual morph: Undetermined

Culture characteristics: Ascospores germinating on PDA within 24 hours. Colonies on MEA effuse, greyish white to yellowish-brown, dense, circular, raised, undulate; reverse dark brown, reaching 3–4 cm diameter within 30 days at room temperature under natural light.

Habitat：Undetermined

Distribution: China

GenBank Accession Numbers：LSUMZ433248,SSUMZ429435.ITSMZ429434.

Notes：There are ten species accepted in Halobyssothecium, four species are known from the asexual morphs and the other six species are known as sexual morphs (Dong et al. 2020, Calabon et al. 2021a). In our phylogenetic analyses, our new collection of H. thailandica was placed within Halobyssothecium and is sister to the asexual species, H. kunmingense and H. bambusicola with 76 ML/0.95 PP bootstrap support . Our new collection fits well with the generic concept of Halobyssothecium in having immersed to semi-immersed, carbonaceous ascomata and 8-spored, clavate to subcylindrical asci with short pedicels and brown, septate ascospores. However, H. thailandica can be easily distinguished from other Halobyssothecium species by its light brown to dark brown and 4–7-septate ascospores surrounded by a gelatinous sheath, while other Halobyssothecium species are less than 4-septate and lacking a gelatinous sheath . Halobyssothecium thailandica resembles H. cangshanense, H. carbonneanum and H. voraginesporum in having cylindric-clavate and brown ascospores, however, H. thailandica differs in having larger asci and larger ascospores with a greater number of septa . Halobyssothecium thailandica has similar ascospore sizes as H. estuariae, H. obiones and H. versicolor. However, H. thailandica can be distinguished by the colour and septation of the ascospores; H. thailandica has light brown to brown, 7-septate ascospores, while ascospores of H. estuariae, H. obiones and H. versicolor are 3-septate and central cells are pale brown to dark brown with hyaline end cells (Dayarathne et al. 2018, Devadatha et al. 2020, Calabon et al. 2021a). In addition, H. thailandica is the only species in the genus that has ascospores with a gelatinous sheath.

Reference：[1] Karim, M. ,   Kavosi, M. R. ,  Mosazadeh, S. A. , &  Hajizadeh, G. . (2013). New fungal records for the iran mycota from hyrcanian forests. Middle East Journal of Scientific Research, 14(5), 729-733.

a, b Appearance of ascomata on the host. c Sections of ascomata. d, e Section of peridium. f Pseudoparaphyses. g–j Asci. k–n Ascospores. o, p Colony on MEA. Scale bars: c = 200 μm, d = 30 μm, e–f, k–n = 20 μm, g–j = 50 μm.4