Phaeosphaeria musae Sawada, Special Publication College of Agriculture, National Taiwan University 8: 66 (1959)
Pathogen on Asparagaceae and Marantaceae. Sexual state: Ascomata 110–140.5 µm high, 120–160 µm diam., solitary, scattered, immersed, visible as slightly raised, small black dots on host surface, uniloculate, brown to dark brown, globose to subglobose, central ostiole with minute papilla. Peridium 7–24 µm wide, thin-walled, of unequal thickness, slightly thick at the apex, composed of 1–3 layers of brown to dark brown, pseudoparenchymatous cells multi-layered and elongated, at the apex, arranged in textura angularis. Hamathecium composed of numerous, 1.5–3 µm wide, filiform, broad cellular pseudoparaphyses, with distinct septa, slightly constricted at the basal septa, embedded in gelatinous matrix, rarely anastomosing at the apex. Asci (40–)65–70(–76) × (9–)13–15(–17) µm ( = 69 × 14.2 μm, n = 25), 8-spored, bitunicate, fissitunicate, broadly cylindric-clavate to clavate, subsessile, with acute ends, apically rounded with indistinct ocular chamber. Ascospores (16–)25–30(–33.5) × 5–7.5 µm ( = 27.6 × 5.8 μm, n = 30), overlapping 2–3-seriate, phragmosporous, fusiform, yellowish-brown to brown, becoming dark brown when stained in 5 % KOH, 3-septate, slightly constricted at the central septa, enlarged at the second cell, slightly curved, rarely straight, rough-walled, echinulate, surrounded by narrow mucilaginous sheath. Asexual state: Unknown.
Culture characters: Colonies on MEA 25–27 mm diam. after 4 weeks at 25–30 ◦C, white yellowish or grey in the centre and edges; reverse yellowish-brown to greyish-yellow or olive brown, with rare tufting, radiating with dark brown colouration separating the margin from the centre; medium dense, irregular, flattened to slightly raised, dull with undulate edge, floccose or velvety, forming black stromatic tissues, embedded in agar after 8 weeks, agar tinted with yellowish-brown pigmentation.
Material examined: THAILAND, Pha Yao Province, Mae Jai District, Sri Don Kaew Village, on living leaves of Calathea sp. (Marantaceae), 19 August 2010, R. Phookamsak RP0049 (MFLU 11-0169), living culture = MFLUCC 11-0133; THAILAND, Chiang Rai Province, Muang District, Pakha village, on living leaves of Cordyline sp. (Asparagaceae), 15August 2010, S. Wikee (RP0067), MFLU11-0187, living culture = MFLUCC 11-0151.
Notes: Phaeosphaeria species (MFLUCC 11-0133 and MFLUCC 11-0151) were isolated from necrotic leaf spots symptoms on Calathea sp. and Cordyline sp. from Thailand. These two collections have similar morphological characters with Phaeosphaeria musae and Ph. panici (P. Syd.) Shoemaker & C.E. Babc. However they differ from Phaeosphaeria panici in having larger ascomata and asci and being associated with a different host. Phaeosphaeria panici lacks molecular data to confirm a natural placement, while these isolates form a strongly-supported clade (70% MP) with Ph. musae in the Phaeosphaeria sensu stricto clade. Based on the ITS and TEF1 pair wise comparisons and multigene phylogenetic evidence, it appears that these isolates are conspecific with Phaeosphaeria musae. Thus, they are identified as Phaeosphaeria musae, and the species is reported associated with leaf spot disease on Calathea sp. and Cordyline sp from Thailand. Pathogenicity was not confirmed.
Fig. 1 Phaeosphaeria musae. (MFLU 11-0169). a Ascomata on host surface. b Section through ascoma. c Section through peridium. d Pseudoparaphyses. e–h Asci. i–m Ascospores. Note sheath in m. Scale bars: b = 50 µm, c, d, e, f, g, h, = 20 µm, i, j, k, l, m = 10 µm.
