Terriera sigmoideospora J.F. Zhang & K.D. Hyde, 2020

Zhang, Jin-Feng, Liu, Jian-Kui, Hyde, Kevin D., Ekanayaka, Anusha H. & Liu, Zuo-Yi, 2020, Morpho-phylogenetic evidence reveals new species in Rhytismataceae (Rhytismatales, Leotiomycetes, Ascomycota) from Guizhou Province, China, MycoKeys 76, pp. 81-106 : 81

Terriera sigmoideospora J.F. Zhang & K.D. Hyde sp. nov. Figure 5

Holotype.

MFLU 18-2297.

Etymology.

Refers to its sigmoidal ascospores.

Description.

Apothecia developing on fallen leaves, scattered, dark brown to black, matt, elliptical, sometimes 3-lobed or triangular, straight or slightly curved, ends rounded to subacute, strongly raising the surface of the substrate at maturity, opening by a single longitudinal split that extends almost the whole length of the apothecium (Fig. 5a, b ). Immature apothecia appearing as a single dark brown protrusion, circular to slightly elongated. In median vertical section (Fig. 5d ), apothecia 185-220 μm deep. Covering stroma (Fig. 5c ) 20-25 μm thick near the centre of the apothecium, consisting of an outer layer of host cuticle, remains of epidermal and hypodermal cells filled with thick-walled, angular fungal cells and an inner layer of textura angularis to textura globulosa with 4-7 μm diam., dark brown, thick-walled cells, slightly thinner towards the edges, extending to the basal stroma, but conspicuously thicker towards the apothecial opening, with a 15-27 μm thick extension comprising highly melanised tissue with no obvious cellular structure. Excipulum moderately developed, closely adhering to the covering stroma and the extension, arising from the marginal paraphyses, becoming thinner towards the base. Basal stroma concave, 12-15 μm thick, composed of dark brown, thick-walled, angular cells. A triangular space between the covering stroma and basal stroma is composed of thin-walled, colourless cells that are vertically arranged in rows. Subhymenium 6-9 μm thick, flat, consisting of hyaline cells of textura intricata. Paraphyses filiform, hyaline, septate, gradually or suddenly swollen to 2.5 μm near the apex, covered by a thin gelatinous sheath, forming a 4-8 μm thick epithecium. Asci (93.5-)102-121 × 5-6 μm (x ¯ = 108.5 × 5.5 µm, n = 20), 8-spored, unitunicate, cylindrical, apex tapering to round, thin-walled, J-, without circumapical thickening. Ascospores 79-95 × 1.5-2 μm (x ¯ = 89.5 × 1.9 µm, n = 30), fascicle, filiform, sigmoid, tapering slightly towards the ends, hyaline, aseptate, guttulate, gelatinous sheath not observed. Asexual morph: Not observed.

Material examined.

CHINA, Guizhou Province, Guiyang, dead leaves of unidentified host, 5 October 2016, J.F. Zhang, GZ-28 (MFLU 18-2297, holotype); ibid. (GZAAS 19-1729, isotype).

Notes.

In the present phylogenetic analysis (Fig. 1 ), Terriera sigmoideospora is placed within Terriera and is related to T. houjiazhuangensis C.L. Hou & S.R. Hou by strong statistical support (MPBP 99% and BYPP 1.00). Terriera sigmoideospora shares similar-sized asci with T. houjiazhuangensis (102-121 × 5-6 μm vs. 103-128 × 4-6 μm), but has larger ascospores (79-95 × 1.5-2 μm vs. 73-82 × 0.6-0.9 μm) ( Cai et al. 2020). Besides, the ascospores of T. houjiazhuangensis are enveloped by an inconspicuous gelatinous sheath, while this is not observed in T. sigmoideospora . In addition, the comparison of the ITS gene region between these two taxa has been processed and showed that there are 19/815 (2.3%) bp differences. Terriera pandanicola is sister to the above two taxa; however, it is significantly distinguished from T. sigmoideospora as its obviously smaller asci (50-66 × 4-5 μm vs. 102-121 × 5-6 μm) and ascospores (55-78 × 1-2 μm vs. 79-95 × 1.5-2 μm) ( Tibpromma et al. 2018).

Figures

Figure 1. Phylogram of Rhytismataceae is presented as the best tree revealed by MP analysis, based on the concatenated LSU-ITS-mtSSU sequence dataset. MP bootstrap support values (MPBP ≥ 50 %) and Bayesian inference posterior probabilities (BYPP ≥ 0.95) are shown near the nodes. The tree is rooted to Marthamyces emarginatus (ICMP 22854), the scale bar showing 10 changes. Type strains are indicated in bold and new sequences, generated in this study, are given in red.

Figure 5. Terriera sigmoideospora a, b apothecia observed under the dissecting microscope c section of covering stroma d median vertical section through an apothecium e immature ascus f paraphyses and asci in various states of maturity g, h ascospores. Note: c-h mounted in water. Scale bar: 1 mm (a), 500 µm (b), 100 µm (c), 20 µm (d-h).