Dothiorella obovata Rathnayaka & K.D. Hyde, 2022

Rathnayaka, Achala R., Chethana, K. W. Thilini, Phillips, Alan J. L. & Jones, E. B. Gareth, 2022, Two new species of Botryosphaeriaceae (Botryosphaeriales) and new host / geographical records, Phytotaxa 564 (1), pp. 8-38 : 17

Dothiorella obovata Rathnayaka & K.D. Hyde , sp. nov.

Index Fungorum number: IF559719; Facesoffungi number: FoF 11668; Fig. 5

Etymology:—In reference to obovate-shaped ascospores.

Holotype:— MFLU 22-0094

Saprobic on dead twig of Pavonia odorata . Sexual morph: Ascomata 195–250 μm high × 170–240 μm diam. (x̄ = 215 × 200 μm, n = 10), immersed to erumpent through host tissue, globose, solitary and scattered. Peridium 34–90 μm wide, 5–7 layers, brown to dark brown cells of textura angularis. Hamathecium comprising 2–4 μm wide, oblong to cylindrical, septate pseudoparaphyses. Asci 60–95 × 12–25 μm (x̄ = 75 × 18 μm, n = 10), 8-spored, bitunicate, fissitunicate, cylindric-clavate to clavate, with a short pedicel, slightly curved, apically rounded with a well-developed ocular chamber. Ascospores 12–17 × 6–10 μm (x̄ = 14 × 8 μm, n = 30), 1–2-seriate, overlapping in the ascus, hyaline to yellowish brown, aseptate when immature, becoming brown to dark brown, 1-sepate at maturity, obovoid, with granular appearance, upper cell is wider than lower cell, straight. Asexual morph: Undetermined.

Culture characteristics:— Conidia germinating on PDA within 24 h. Germ tubes produced from one side of the conidium. Colonies on PDA reaching 2.0– 2.5 cm diam. after 5 days at 25 °C, circular, medium dense, flat or effuse, slightly raised, fluffy to fairly fluffy, aerial, grey colour in top view, black in bottom view.

Material examined:— THAILAND. Trat province (Southern Thailand): on dead twig of Pavonia odorata (Malvaceae) , 3 September 2020, Rashika Sajith (MFLU 22-0094, holotype); ex-type living culture MFLUCC 22- 0058.

Notes:— Dothiorella obovata fits within the generic concept of Dothiorella by having pigmented, 1-septate ascospores. Morphologically, our new strain (MFLU 22-0094/ MFLUCC 22-0058) is distinguished from other Dothiorella species by having obovate ascospores. Based on multi-gene phylogeny (ITS, LSU, tef 1-α and β-tub), D. obovata constitutes a distant lineage sister to D. brevicollis , D. diospyricola , D. lampangensis , and D. longicollis with relatively high 97% ML bootstrap and 1.00 PP support ( Fig. 1 ). Only asexual morphs have been recorded for D. brevicollis , D. diospyricola , D. lampangensis , and D. longicollis , while D. obovata is recorded from the sexual morph. Therefore, we could not compare the morphology of D. obovata with these four species. Base pair differences between D. brevicollis , D. diospyricola , D. lampangensis , D. longicollis and D. obovata (MFLUCC 22-0058) are shown in Table 2 . According to distinct morphology and phylogenetic evidence, we established D. obovata as a new species in Dothiorella .

Figures

FIGURE 1. Phylogram generated from ML analysis based on combined dataset of ITS, LSU, tef1-α and β-tub. The tree is rooted to Neofusicoccum luteum (CMW 4165 and CBS 562.26). Tree topology is similar to the previous study by Zhang et al. (2021). Bootstrap support values for ML ≥ 70% and Bayesian posterior probabilities (PP) ≥ 0.90 are noted at the nodes. Strain numbers are noted after the species names. Strains isolated in this study are presented in red and type strains are in bold.

FIGURE 5. Dothiorella obovata on dead twig of Pavonia odorata (holotype: MFLU 22-0094). a, b. Appearance of ascostromata on host surface. c, d. Section through ascomata. e. Section through peridium. f. Pseudoparaphyses. g–j. Asci. k–n. Ascospores. O. Germinating ascospore. p, q. Colony on PDA (p upper, q lower). Scale bars: a = 1 mm, b = 500 μm, c, d =100 μm, e, f = 10 μm, g–j = 20 μm, k–o = 5 μm.