Melomastia puerensis R.F. Xu & Tibpromma, 2024

Xu, Rui-Fang, Karunarathna, Samantha C., Phukhamsakda, Chayanard, Dai, Dong-Qin, Elgorban, Abdallah M., Suwannarach, Nakarin, Kumla, Jaturong, Wang, Xiao-Yan & Tibpromma, Saowaluck, 2024, Four new species of Dothideomycetes (Ascomycota) from Para Rubber (Hevea brasiliensis) in Yunnan Province, China, MycoKeys 103, pp. 71-95 : 71

Melomastia puerensis R.F. Xu & Tibpromma sp. nov.

Fig. 2

Etymology.

The name refers to the location “Pu’er, Yunnan, China", where the holotype was collected.

Holotype.

ZHKU 23-0106.

Description.

Saprobic on a dead branch of Hevea brasiliensis . Sexual morph: Ascomata 260-720 μm high, 225-850 μm diam. (x‾ = 540 × 520 μm, n = 10), visible as black dots on the host surface, solitary or gregarious, immersed to slightly erumpent, subglobose or pyriform, carbonaceous, dark brown to black, ostiolate, papillate. Ostioles 205-220 × 195-258 µm (x‾ = 233 × 207 μm, n = 5), central, carbonaceous, dark brown to black. Peridium 40-120 µm wide, two-layered, outer layer, thick, carbonaceous, inner layer composed of several layers, brown to pale brown cells of textura angularis. Hamathecium comprises 2-4.5 μm wide, filiform, unbranched, hyaline, aseptate, guttulate, pseudoparaphyses, longer than asci. Asci 175-205 × 6-10 μm (x‾ = 190 × 8, n = 15), 8-spored, hyaline, bitunicate, cylindrical, flexuous, apically obtuse, with an ocular chamber, smooth-walled, short pedicellate. Ascospores 20-30 × 5-8 μm (x‾ = 24 × 7, n = 30), uniseriate, hyaline, fusiform, obtuse or conical ends, narrow towards the apex, 3-septate, constricted at the central septum, with guttulate in each cell. Asexual morph: Undetermined.

Culture characteristics.

Colonies on PDA that grow at 28 °C, flat, rough surface, entire edges, culture from above, brownish-grey, forming zonate grey, reverse dark brown, brown at the edge, turning reddish-brown.

Material examined.

China, Yunnan Province, Pu'er on a dead branch of Hevea brasiliensis , 16 September 2021, Rui-Fang Xu, XPER-14 (ZHKU 23-0106, holotype); ex-type ZHKUCC 23-0802, ZHKUCC 23-0803 .

GenBank numbers.

ZHKUCC 23-0802 = ITS: OR941077, LSU: OR922309, SSU: OR922340, tef 1-α: OR966284; ZHKUCC 23-0803 = ITS: OR941078, LSU: OR922310, SSU: OR922341, tef 1-α: OR966285.

Notes.

The phylogenetic analyses showed that Melomastia puerensis clustered basal to M. distoseptata , M. fusispora , M. maomingensis , M. oleae , M. pyriformis , M. thamplaensis and M. winteri with 99% MP, 1.00 PP support (Fig. 1 ). We compared the morphology of our collection with closely-related species and the differences are mentioned in Table 2 . Our collection has slight differences from other closely-related species by having larger ascomata and wider peridium, but the phylogenetic tree shows that they are different species (Fig. 1 , Table 2 ). Therefore, we introduce M. puerensis as a new species, based on morphology and phylogenetic analyses.

Pleosporales Luttrell ex M.E. Barr

Figures

Figure 1. Phylogram generated from Maximum Likelihood analysis, based on combined LSU, SSU and tef 1 - α sequence data of 41 taxa, which comprised 2836 base pairs (LSU = 902 bp, SSU = 1031 bp, tef 1 - α = 903 bp). The best scoring RAxML tree with a final likelihood value of - 14798.632437 is presented. The matrix had 1013 distinct alignment patterns, with 24.90 % of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.241740, C = 0.258134, G = 0.292403, T = 0.207722; substitution rates: AC = 0.834723, AG = 2.021967, AT = 1.126143, CG = 1.032150, CT = 7.231944, GT = 1.000000; gamma distribution shape parameter α = 0.320795. Bootstrap support values for ML equal to or greater than 60 % and Bayesian Inference analysis values equal to or greater than 0.90 PP are labelled at each node. The tree is rooted with Anisomeridium phaeospermum (MPN 539) and A. ubianum (MPN 94). Related sequences were collected following Li et al. (2022), Kularathnage et al. (2023) and Dong et al. (2023). The new isolates are indicated in red and the ex-type strains are in bold. Group A indicates the taxa used to compare the morphology with our new species (Melomastia puerensis).

Figure 2. Melomastia puerensis (ZHKU 23 - 0106, holotype) a-c appearance of ascomata on host surface d vertical section of an ascoma e vertical section of ostiole f section of peridium g hamathecium h-l asci m-q ascospores r asci stained in Lugol's iodine s germinated ascospore t, u colonies on PDA (t-front and u-reverse views). Scale bars: 100 µm (d-f); 50 µm (g-l); 10 µm (m-q); 30 µm (s).