Diatrype thailandica R.H. Perera, J.K. Liu&K.D.Hyde, sp. nov.
Index Fungorum number: IF 552008, Facesoffungi number: FoF 01797, Figs. 1, and 2
Etymology – The specific epithet thailandica refer to the country in which the fungus was first collected.
Holotype – MFLU 15–3662

Saprobic on wood. Sexual morph Stromata 1 – 1.2 mm wide, scattered on host, erumpent, arising through the cracks in bark epidermis, with 4 ascomata immersed in a single stromata, comprising an outer, dark brown to black, small, tightly packed, thin parenchymatous cell layer, inner layer yellowish, loosely packed, with parenchymatous cells, with ostioles opening to outer surface, appearing as black spots. Ascomata 226 – 336 μm high, 177 – 235 μm diam., (x̄ = 282 × 209 μm, n = 20), perithecial, immersed in stromatic tissues, aggregated, globose to subglobose, narrowing towards the apex, pale brown, ostiolate. Ostiolar necks emerging separately, short, immersed in only dark outer layer of stromata, conical, periphysate. Peridium 6.5 – 15 μm wide (x̄ =11 μm, n = 20), comprising strata of 4 – 8 layers of cells of hyaline to dark brown cells of textura angularis. Hamathecium comprising 2.2 – 4.5 μm wide (x̄ = 3 μm, n = 20), aseptate, paraphyses, longer than the asci, wider at the apex. Asci 55 – 80 × 5–7 μm (x̄ = 67 × 6 μm, n = 25), 8-spored, unitunicate, with narrow, long, thin-walled pedicel, with cylindrical, thick-walled, swollen upper portion, apex flat, with J-, conspicuous apical apparatus. Ascospores 3.8 – 6.9 × 1 – 1.4 μm (x̄ = 5.4 × 1.2 μm, n = 20), multi-seriate to overlapping pale brown, allantoid to cylindrical, unicellular, with small, fat globules at the ends, smoothwalled. Asexual morph Coelomycetous, libertella-like, Mycelial clumps white. Conidiomata pycnidial, 0.4 – 1 mm diam., brownish yellow, becoming dark brown when mature, watery, bubble-like, rounded, conidial masses forming from mycelial clumps. Pycnidia superficial, solitary or aggregated, subconical, globose to subglobose, shiny, with smooth surface, yellow, dark brown, comprising brown, thick-walled cells of textura angularis. Conidiophores 12 – 16 μm high, 1.8 – 2.3 μm wide (x̄ = 14 × 2.1 μm, n = 20) branched, arising from pseudoparenchymatous cells or interwoven hyphae. Conidiogenous cells 5.9 – 10 μm high, 1.1 – 1.8 μm wide (x̄ = 8.4 × 1.6 μm, n = 20), cylindrical, in dense palisades, straight or curved, apically distorted or bearing annellations. Conidia 14.2 – 18 × 0.7 – 1 μm (x̄ = 16.7 × 0.9 μm, n = 20), filiform, curved or rarely straight, with flattened base and blunt apex, hyaline.

Culture characteristics – Fast growing, reaching 6.7 cm within 14 days on PDA, at 25 °C, circular, flat, with diffuse margin, white, and becoming yellowish-white, dull yellow to brownish with age.

Material examined – THAILAND, Doi Mae Salong, on stems of unidentified plant, 12 March 2015, R.H. Perera, RHP 27 (MFLU 15–3662, holotype); ibid., HKAS 92497, isotype), ex-type living culture, MFLUCC 14–1210, CUMCC 15-0019.

Notes – Based on the phylogenetic analysis of ITS sequence data, Diatrype thailandica form a separate branch as a sister group with Diatrypella and Diatrype species. Previous studies by Trouillas et al. (2011) and Acero et al. (2004) suggested that both Diatrypella and Diatrype are polyphyletic within the family. However Diatrype thailandica is morphologically similar to the members of the genus Diatrype in both sexual and asexual morph characteristics. In the phylogenetic analysis it has a close relationship with D. macowaniana which was isolated from dead branches of Cassina capensis in South Africa. Diatrype thailandica is different from D. macowaniana in having yellow inner cells in the stromata, with smaller, pale brown, mostly allantoid ascospores, and longer asci, while D. macowaniana is characterized by stromata with white inner cells, larger, cylindrical ascospores and smaller asci. Diatrypaceae is a taxonomically confused family and it is presently difficult to segregate genera (Trouillas et al. 2011; Vasilyeva et al. 2006; Liu et al. 2015). Therefore, the placement of this isolate into the genus Diatrype may require reconsideration in the future together with a revision for the entire family.

Fig. 1 Diatrype thailandica (holotype) a Herbarium material b – d Appearance of stromata on host substrate. e Longitudinal section through stroma f Vertical section through stroma showing ascomata g Close up of the ostiole h Close up of the peridium i Paraphyses j Arrangement of asci k Ascus inMelzer’s reagent l Immature and mature asci m Ascospores n Germinating ascospore. Scale bars: b = 2 mm, c – e = 500 μm, f = 50 μm, g – j = 20 μm, k = 100 μm, l = 10 μm, m = 20 μm, n, o = 10 μm.

Fig. 2 Diatrype thailandica (holotype) a, b Conidiomata on PDA c Cross section of conidioma d Conidia attached to conidiophores e Conidia f Sporulation on one month old culture on PDA, 25 °C. Scale bars: a, b = 1 mm, c – e = 20 μm.