Melomastia puerensis R. F. Xu & Tibpromma

Zhang, Xian, Tibpromma, Saowaluck, Karunarathna, Samantha C., Du, Tian-Ye, Han, Li-Su, Elgorban, Abdallah M., Kumla, Jaturong, Senwanna, Chanokned, Dai, Dong-Qin, Suwannarach, Nakarin & Wang, Hao-Han, 2025, Additions to the saprobic fungi (Ascomycota) associated with macadamia trees from the Greater Mekong Subregion, MycoKeys 113, pp. 1-29 : 1-29

Melomastia puerensis R. F. Xu & Tibpromma , MycoKeys 103: 75 (2024)

Fig. 8

Holotype.

ZHKU 23-0106 .

Description.

Saprobic on dead twigs of Macadamia integrifolia . Sexual morph: Ascomata 300–650 × 430–605 µm (x ̄ = 521 × 516 µm, n = 20), visible as black raised dots on the host surface, solitary, semi-immersed, dark brown to black, subglobose or irregular pyriform, carbonaceous, papillate. Ostiolar central, carbonaceous, brown to dark brown to black. Peridium 30–80 µm wide (x ̄ = 52 µm, n = 25), comprising two section layers: inner section layers hyaline to brown cells of textura prismatica, outer section layer, brown to black cells of textura prismatica. Hamathecium 2–4 µm wide (x ̄ = 3 μm, n = 60), hyaline, filiform, septate, branched, pseudoparaphyses, longer than asci. Asci 166–235 × 5.6–9.9 µm (x ̄ = 196 × 8.1 µm, n = 30), 8 - spored, bitunicate, cylindrical, flexuous, smooth-walled, apically obtuse, with an ocular chamber, short-pedicellate. Ascospores 19–30 × 5–8 µm (x ̄ = 26 × 6.5 µm, n = 50), hyaline, fusiform, uniseriate, 3 - septate, narrow towards the apex and obtuse or conical ends, constricted at the septa, smooth-walled, without mucilaginous sheath or appendages, with guttules in each cell. Asexual morph: Undetermined.

Material examined.

China • Yunnan Province, Baoshan City , 24°48'18"N, 99°22'36"E, 1199.6 m elevation, on a dead branch of Macadamia integrifolia , 30 July 2022, Xian Zhang, MBC 85, GMB 1173 , GMB 1174 , new host record .

GenBank number.

GMB 1173 = LSU: PQ 669573, SSU: PQ 669629, tef 1 - α: PQ 685655; GMB 1174 = LSU: PQ 669574, SSU: PQ 669630, tef 1 - α: PQ 685656.

Known host and distribution.

On a dead branch of Hevea brasiliensis in China ( Xu et al. 2024), on a dead branch of Macadamia integrifolia in China (this study).

Notes.

Macadamia puerensis was reported by Xu et al. (2024), who isolated it from Hevea brasiliensis (Willd. ex A. Juss.) Müll. Arg. , in Pu’er City, Yunnan Province, China. In the phylogenetic analyses, our strain M. puerensis (GMB 1173) clustered with M. puerensis ( ZHKUCC 23–0802 , ex-type) with 100 % ML and 1.00 PP support (Fig. 7 ). The nucleotide comparisons showed that our strain is not significantly different from ZHKUCC 23–0802 in LSU (0 / 842 bp (0 %), without gaps), SSU (3 / 1035 bp (0.3 %), without gaps), and tef 1 - α (0 / 903 bp (0 %), without gaps). Morphologically, our collection is nearly identical to the holotype ( ZHKU 23-0106 ), including the ascospores size (19–30 × 5–8 µm vs. 20–30 × 5–8 μm). Thus, we identified our strain as M. puerensis , representing a new host record on M. integrifolia . Additionally, this marks the first report of Melomastia associated with Macadamia (Table 4 ).

Figures

Figure 7. RAxML tree based on a combined dataset of LSU + SSU + tef 1 - α gene sequences. The topology of the trees generated by both maximum likelihood (ML) and Bayesian inference (BI) analyses exhibited high similarity. The RAxML tree with a final ML optimization likelihood value of - 12726.117171. The aligned matrix had 933 distinct alignment patterns, with 22.57 % of undetermined characters or gaps. Parameters for the GTR + I + G model of the combined LSU, tef 1 - α, and the SYM + I + G model of the combined SSU were as follows: estimated base frequencies A = 0.239385, C = 0.263871, G = 0.289634, T = 0.207110; substitution rates AC = 0.851550, AG = 2.071762, AT = 1.124966, CG = 0.971448, CT = 7.978925, GT = 1.000000; the proportion of invariable sites I = 0.478880; and gamma distribution shape parameter α = 0.661129. Bootstrap support values for ML equal to or greater than 60 % and PP equal to or greater than 0.90 are given above the nodes. New records are in blue, while the ex-type species are in bold.

Figure 8. Melomastia puerensis (GMB 1173, new host record) a, b appearance of ascomata on the host surface c section of peridium d vertical section of an ascoma e ocular chamber in lactophenol cotton blue reagent f, k hamathecium g – j asci l – p ascospores. Scale bars: 200 µm (d); 100 µm (g – j); 50 µm (k); 20 µm (c, f); 10 µm (l – p).