Fissuroma bambusae Phookamsak & K.D. Hyde, sp. nov.
Index Fungorum number: IF551629
Etymology: The epithet Bbambusae^ refers to the host, of which the fungus was collected.
Holotype: MFLU 11-0196

Saprobic on bamboo. Sexual morph: Ascostromata 250–400μm high, 750–1050μm diam., dark brown, gregarious, immersed beneath host epidermis, visible as numerous, raised, dome-shaped areas on the host surface, hemisphaerical, flattened or wedge-shaped at the base, uni-loculate, glabrous with rough walls, coriaceous, ostiolate. Ostioles central, apapillate, with slightly long carbonaceous, and thin, slit-like opening. Peridium 42–77(–118) μm wide, of unequal thickness, poorly developed at the base, thick at sides towards the apex, composed of several layers, of dark brown to black, pseudoparenchymatous cells, with host cells plus fungal tissue, arranged in a textura angularis to textura prismatica. Hamathecium composed of dense, 0.5–1.5μm wide, filiform, trabeculate pseudoparaphyses, anastomosing among the asci, embedded in a hyaline gelatinous matrix. Asci (150–)170–187 (–194)×(15–)17–19(–22) μm  (x =178.1× 18.5μm, n=30), 8-spored, bitunicate, cylindric-clavate or obclavate, with short furcate to truncate pedicel, apically rounded with a truncate ocular chamber. Ascospores (40–)45–47(–52)×6–8(–9) μm (x =46.2×7.1μm, n=30), overlapping bi- to tri- seriate at the base, uni-seriate at the apex, hyaline, fusiform with acute ends, 1-septate, constricted at the septum, upper cell shorter and wider than lower cell, smooth-walled, surrounded by a thick, distinct sheath. Asexual morph: producing conidiomata on colonies growing on PDA after 3 months. Conidiomata large, scattered, immersed to semi-immersed, visible as black dots on PDA media agar, globose to subglobose, composed of dark brown to black, pseudoparenchymatous cells. Conidiophores (4.5–)(8–)10–20(–32)×1.5–3.5μm (x =15.7×1.9μm, n= 40), arising from basal cavity, cylindrical, simple to branched, hyaline, septate, smooth-walled. Conidiogenous cells holoblastic, phialidic, determinate, integrated, or discrete, hyaline, lageniform or cylindrical, smooth-walled. Conidia (2–)3–4.5×1.5–2μm (x =3.6×1.7μm, n=50), hyaline, oblong, or rod-shaped with rounded ends, aseptate, with two small guttules, smooth-walled.

Culture characteristics: Colonies on MEA reaching 35–45 mm diam. after 4 weeks at 25–30 °C, colonies circular, medium dense, flattened, slightly raised near margin, dull, surface slightly rough with edge entire, fluffy to floccose, slightly radiating with concentric ring of cottonny mycelium at edge of colony; colony from above, white to white greyish with black, small droplets, laterally forming dark, dull, irregular, rough, flaky, white, sponge-like areas; from below: brown at the margin, dark brown to black at the center, slightly radiating with dark concentric ring; producing dark brown to black pigmentation in agar.

Material examined: THAILAND, Chiang Rai Province, Muang District, Khun Korn Waterfall, on dead stem of bamboo, 5 September 2010, R. Phookamsak, RP0076 (MFLU 11-0196, holotype), living cultures, MFLUCC 11-0160, BCC; ibid., on dead stem of bamboo, 17 December 2010, R. Phookamsak, RP0114 (MFLU 11-0234), living cultures, MFLUCC 11-0198, BCC.

Notes: Fissuroma bambusae differs from F. thailandicum in having a thin, slit-like ostiole, and larger ascospores (x = 46.2×7.1μm). In F. thailandicum the ostiole is long, wide, shiny and rim-like, and ascospores are smaller (x =45.4×7.1μm). In the phylogenetic analyses (Fig. 1), F. bambusae forms a robust clade with F. thailandicum and F. neoaggregata (100 % MP, 100 % ML, 1.00 PP) in Aigialaceae, but is distinct. A comparison of the TEF1 sequence data of F. bambusae and F. thailandicum shows a difference of 17 base positions. Tanaka and Harada (2005) reported the asexual morph of F. aggregata as coelomycetous and pleurophomopsis-like, with globose to subglobose conidiomata, phialidic conidiogenous cells and hyaline, globose conidia. Fissuroma bambusae formed the asexual morph in culture on MEA. The asexual morph is coelomycetous, but differs from F. aggregata in having oblong conidia (Fig. 2).

 

Fig. 1 A Bayesian 50%majority rule consensus tree based on combined„ dataset of LSU, SSU and TEF1 alignments. Bootstrap support values for maximum likelihood (ML, blue) and maximum parsimony (MP, green) equal or greater than 60 % are given above the nodes. Bayesian posterior probabilities (BYPP, red) equal or higher than 0.95 are given below the nodes. Hysterium angustatum (CBS 123334, CBS 236.34) was selected as an outgroup taxon. Ex-type strains are in bold. Newly generated sequences are in red and the type species are indicated in blue.

 

Fig. 2 Fissuroma bambusae (MFLU11-0196, holotype). a Appearance of ascostromata on host surface. b Section through ascostroma. c Section through peridium. d Asci embedded in trabeculate pseudoparaphyses. e–g Asci. h–j Ascospores. k Ascospore stained with Indian ink. l–m Culture characters on MEA (m=from above, n=from below). n Conidiomata on colony. o, p Conidiophores. q–t Conidia. Scale bars: b=200μm, c=50μm, d=20μm, d–g, h–k, o, p=10μm, q= 5μm, r–t=2μm