Melomastia septemseptata, Naziazeno & Aptroot, 2023

Naziazeno, Leticia Muxfeldt & Aptroot, André, 2023, New species and records of mostly lignicolous dothideomycetous ascomycetes from Brazil, Cryptogamie, Mycologie 20 (1), pp. 1-9 : 2

Melomastia septemseptata sp. nov.

( Figs 1-4 )

HOLOTYPE. — Brazil. Mato Grosso do Sul, Campo Grande, Vila Carlota , 3.III.2021, alt. 600 m, 20°29’S, 54°36’W, on tree bark, A. Aptroot 82290 (holo-, CGMS; iso-, ABL).

MYCOBANK. — MB 846359.

DESCRIPTION

Corticolous Melomastia with 7 to 11-septate ascospores.

Thallus corticolous, only visible as a whitish stain, not lichenized. Ascomata pseudothecioid, conical, 0.5-1.0 mm diam. Ostiole apical. Wall carbonized above, greenish black, but barely below the hamathecium, up to 50 µm thick. Paraphyses not branched, c. 2 µm wide. Ascospores 8/ascus, hyaline, thick-walled with lumina fusiform, 7(-11)-septate, (21-)25-30 × 6.5-8.0 µm diam. Pycnidia not observed.

REMARKS

The specimen was found on living bark of a Cerrado tree. All known species of Melomastia ( Li et al. 2022) occur saprophytic in marine, aquatic or dry terrestrial habitats. The number of septa in the ascospores in Melomastia septemseptata sp. nov. is seven to eleven. In most dry terrestrial representatives of Melomastia (e.g. M. fusispora W.L. Li, Maharachch. & Jian K. Liu, M. oleae W.L. Li, Maharachch. & Jian K. Liu, M. sichuanensis W.L. Li, Maharachch. & Jian K. Liu and M. winteri W.L. Li, Maharachch. & Jian K. Liu ), the number of septa per ascospores is three. No previously known species of Melomastia was known to occur on living bark. The colouration of the fruiting body found in the Melomastia specimens ranges from dark brown to black in contrast to M. septemseptata sp. nov., which is dark green.

Figures

FIG. 1. — Habitus of Melomastia septemseptata sp. nov. (holo-, CGMS). Scale bar: 5 mm.

FIG. 2. — Section through ascoma of Melomastia septemseptata sp. nov. (holo-, CGMS). Scale bar: 200 μm.

FIG. 3. — Section through ascoma of Melomastia septemseptata sp. nov. (holo-, CGMS). Scale bar: 20 μm.

FIG. 4. — Ascospores of Melomastia septemseptata sp. nov. (holo-, CGMS). Scale bar: 10 μm.