Phaeoacremonium aureum C.F.J. Spies, Moyo, Halleen & L. Mostert

Dayarathne, Monika C., Maharachchikumbura, Sajeewa S. N., Gareth Jones, E. B., Al-Sadi, Abdullah M., Hyde, Kevin D. & Chomnunti, Putarak, 2019, Sexual morph of Phaeoacremonium aureum from Rhizophora mucronata collected in southern Thailand, Phytotaxa 387 (1), pp. 21-39 : 26-28

Phaeoacremonium aureum C.F.J. Spies, Moyo, Halleen & L. Mostert ( Fig. 2 )

Facesoffungi number: FoF 03772

Saprobic on aerial bark of Rhizophora mucronata . Sexual morph: Ascomata astromatic, immersed in decaying wood, only necks emerging, scattered; venter 150−250 μm diam., 120–200 μm high, subglobose, black; neck central, 100–150 μm wide, 300–380 μm long, conical, straight. Ostiole periphysate. Ascomatal wall 15–20 μm thick, two-layered; outer layer consisting of brown textura angularis, towards the interior grading into several layers of thin-walled subhyaline to hyaline flattened cells. Paraphyses persistent, septate, slightly inflated between the septa near their base, hyaline, 1.5–2 μm wide near the base, about 1 μm wide at the apex, longer than the asci. Asci 12–15.5 × 2.5–4 μm (x = 14 × 3.0 μm, n = 10), arising in acropetal succession, clavate, apex broadly rounded to obtuse, thickened to 1–2 μm, floating freely in the centrum upon maturation, 8-spored. Ascogenous hyphae hyaline, branched, smooth-walled. Ascospores 3.5–4.5 × 0.5–1.5 μm (x = 4 × 1 μm, n = 20), bi-seriate, suballantoid with rounded ends, slightly curved, hyaline, smooth, aseptate, containing small guttules at the ends. Asexual morph: Hyphomycetous. See Spies et al. (2018) for detailed description.

Material examined:— THAILAND. Krabi Province:Tha Pom Khlong Song Nam (N08°12’50.4”, E 98°46’42.7”), on aerial bark of Rhizophora mucronata , 16 December 2015, M. C. Dayarathne ( MFLU 17-1581).

Notes:— Phaeoacremonium aureum shares similar morphological features of other Phaeoacremonium sexual morphs such as long necked ascomata, two-layered peridium of textura angularis, asci arising in acropetal succession with a thickened ascal apex, hyaline ascogenous hyphae and suballantoid to oblong ascospores. Phaeoacremonium aureum is different from other species in the genus by having ascomata with relatively long (300–380 μm) conical necks and suballantoid to oblong, slightly curved ascospores with rounded ends, with small guttules. Furthermore, it is significant in being saprobic on Rhizophora mucronata as this is the first report of Phaeoacremonium from a saline environment. The species of Phaeoacremonium are compared in Table 2. Base pair comparison of actin gene sequences of our strain with the type strain of P. aureum (asexual morph) showed that they were identical. Phaeoacremonium aureum , which was recently introduced by Spies et al. (2018), is phylogenetically related to P. fuscum and P. venezuelense and until now, its sexual morph was undetermined.

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Figures

FIGURE 2. Sexual morph of Phaeoacremonium aureum (MFLU 17-1581). a–c. Appearance of ascomata on host surface. d. Vertical section through ascoma. e, f. Peridium. g, k, l. Asci. h. Asci stained with Congo red. i, n.Ascospores. j. Paraphyses. m.Apical thickening. Scale bars c, d = 100 μm, e, f = 20 μm, g = 20 μm, h = 50 μm, i–l = 10 μm, m, n = 5 μm.