Pseudobambusicola thailandica Hern.-Restr. & Crous sp. nov.

Etymology.

The epithet refers to Thailand, where this species was collected.

Type.

THAILAND. Lop Buri Province: Chai Badan, Wang Kan Lueang Arboretum, Wang Kan Lueang Waterfall, on twig (unidentified), 14 Jul 2015, M. Hernández-Restrepo, MHR 1534 (holotype: BBH 42022!, culture ex-type BCC 79462!).

Description of fungal structures on SNA.

Mycelium composed by hyaline to pale brown, septate, smooth to slightly verruculose, hyphae, 1-2.5 µm wide. Conidiomata pycnidial, semi- or entirely immersed in the agar, solitary or aggregated, erumpent, globose, sometimes with a neck, opening via central ostiole, dark brown, 63-360 µm diam., sometimes with a cylindrical neck 50-125 × 40-50 µm, opening via central ostiole; at the base of the conidiomata are often present globose to subglobose cells, thick-walled, 5-9 µm wide; conidiomata surrounded by dark brown, smooth to slightly verruculose hyphae, 2-2.5 µm wide. Conidiophores reduced to conidiogenous cells. Conidiogenous cells phialidic with periclinal thickening, subcylindrical to ampulliform, hyaline, smooth, 6.5-7 × 2.5-4 µm . Conidia exposed in white, mucous drops at the ostiole of pycnidia, composed by macro- and microconidia. Macroconidia produced in white, mucous heads, solitary, fusoid-ellipsoid, apex bluntly to subobtusely rounded, tapering to a distinctly truncate base, mostly straight, but sometimes slightly curved, prominently guttulate, hyaline, smooth, 0-3-septate, 10-20 × 2 –4(– 6) µm . Microconidia produced in the same pycnidia with macroconidia, solitary, oblong to cuneiform, non-guttulate to slightly guttulate, hyaline, smooth, aseptate, 2 –4(– 5.5) × 1-2 µm, apex rounded, base truncate. Chlamydospores brown, terminal, in chains, 16-38 × 5-6 µm . Sexual morph not observed.

Culture characteristics.

Colonies on OA at 25 °C reaching 24 mm diam. in 2 weeks, elevated, with dense cottony mycelium at the centre, mouse grey, margin whitish, effuse to fimbriate; reverse dark mouse grey.

Notes.

Pseudobambusicola is introduced here for a pycnidial coelomycete producing two kinds of conidia. Morphologically, it is similar to the species of Bambusicola and Neobambusicola . However, asexual morphs in Bambusicola are characterised by brown or pale brown conidia and annellidic rather than phialidic conidiogenous cells and hyaline conidia as in Pseudobambusicola (Dai et al. 2012, 2017). Neobambusicola is a monotypic genus erected for N. strelitziae, first described from South Africa growing on necrotic leaf tissue associated with Phyllachora strelitziae ( Phyllachoraceae, Phyllachorales, Sordariomycetes) (Crous et al. 2014). Both genera are similar in having pycnidial conidiomata and phialidic conidiogenous cells that produce fusoid-ellipsoid macro- and subcylindrical microconidia. However, in the new genus, the conidiomata are surrounded by dark brown, smooth to slightly verruculose hyphae and, in mature conidiomata, a cylindrical neck is often present; furthermore, chlamydospores can be present in culture. Although both genera belong to the Sulcatisporaceae ( Pleosporales, Dothideomycetes), they are placed in different clades, Neobambusicola is more closely related to Sulcatispora (100 %, 1 pp), while Pseudobambusicola was placed in a distinct branch with Magnicamarisporium (Fig. 1). Additionally, based on LSU, ITS and tef1 sequences, P. thailandica is 97 % (KP004495) and 83 % (KP004467) and 93 % similar to N. strelitziae, respectively.