Longiostiolum tectonae Doilom, D.J. Bhat & K.D. Hyde, sp. nov.
Index Fungorum number: IF 551900, Facesoffungi number: FoF 01882, Figs. 2, and 3
Etymology: Name refers to the host genus Tectona.
Holotype: MFLU 15–3532

Saprobic on dead bark of Tectona grandis L.f. Sexual morph Ascostromata (255–) 295 – 375 (–500) μm high × (230–) 275 – 335 (–385) μm diam. (x̄ = 340 × 300μm, n = 10), black, solitary to gregarious, scattered, immersed to semi-immersed, when cut horizontally, locules visible as white contents, uniloculate, globose to subglobose, with a central ostiole. Ostiole 110 – 220 μm high, 100 – 170 μm diam., circular, long, central, periphysate. Peridium 58 – 85μm thick, comprising two types of cell layers, outer layer black to brown, thick-walled cells of textura angularis, inner layer composed of hyaline and thin-walled cells of textura angularis. Hamathecium comprising numerous, 1.8 – 2.9 μm wide, hypha-like, filiform, septate, branched, cellular, pseudoparaphyses, embedded in a gelatinous matrix. Asci (105–) 135 – 150 (–195) × 22 – 33 μm (x̄ = 140 × 27 μm, n = 15), 8-spored, bitunicate, clavate, with a short pedicel, apically rounded, with an ocular chamber. Ascospores (52–) 57 – 59 (–63) × 8–12 μm (x̄ = 57 × 10 μm, n = 20), mostly overlapping biseriate to tri-seriate, hyaline when young later pale brown, fusoid to narrowly fusoid, with narrowly rounded ends, constricted at the central septum, slightly constricted at other septa, with 7 – 10 transverse septa, smooth-walled. Asexual morph (see culture characteristics).

Culture characteristics: Ascospores germinating on PDA within 24 h. Colonies on MEA reaching 12 – 17 mm diam. after 7 days in the dark at 25 °C (x̄ = 14.1 mm, n = 5), undulate, fluffy in the center of old mycelium plug, aerial, medium spare, flat or effuse, initially white, becoming brown, grey (7D1) in the center and white (7A1) at the edge from above, light brown (7D6 – 7D7) from below. Colonies producing yellow to brown pigments on MEA and PDA. Mycelium 1 – 4.5μm wide, white to pale brown, branched, septate. Conidia – like structures (3–) 6 – 8 (–11) × (4–) 6 – 7(–9) μm (x̄ = 7 × 6 μm, n = 30), produced on aerial mycelium, subglobose to ellipsoidal, aseptate, initially hyaline, becoming olivacious brown and finally black, terminal and ateral, thick-walled.

Material examined: THAILAND, Chiang Mai Province, Mae Tang District, on dead bark of T. grandis (Lamiaceae), 22 May 2012, M. Doilom, (MFLU 15–3532, holotype), extype living culture MFLUCC 12–0562, MKT 078, ICMP.

Notes: Longiostiolum is introduced as a monotypic genus in the suborder Massarineae with L. tectonae as the type species. The genus has black, immersed to semi-immersed, uniloculate, globose to subglobose ascostromata, with whit  contents, with a long central ostiole and phragmosporous ascospores. Longiostiolum clearly differs from other genera in suborder Massarineae based on phylogenetic analysis and morphology. Although, in this study, the combined phylogeny of LSU, SSU, TEF1α and RPB2 sequence data shows weak support, L. tectonae (isolate MFLUCC 12–0562) however, grouped in a distinct lineage within the suborder Massarineae (Fig. 1). Therefore, we introduce a new monotypic genus to accommodate the taxon.

Fig. 1 Phylogram generated from maximum likelihood analysis based on combined LSU, SSU, RPB2 and TEF sequence data of Pleosporineae and Massarineae, Pleosporales, Dothideomycetes. Maximum likelihood bootstrap support values greater than 50 % are near the nodes. The extype strains are in bold and the new isolates are in blue. The tree is rooted with Halotthia posidoniae BBH 22481.

Fig. 2 Longiostiolum tectonae (holotype) a Ascostromata immersed in dead bark of Tectona grandis b Ascostroma cut horizontally showing the white contents c Peridium d Ascostroma in section e Pseudoparaphyses f, g Immature asci with ascospores h Mature ascus i, j Ascospores. Notes: e – g, i stained with lactophenol cotton blue. Scale bars: a = 500 μm, b = 200 μm, c, d = 100 μm, e = 10 μm, f – j = 20 μm.