Aquilariomyces maomingensis T. Y. Du, K. D. Hyde, Tibpromma & Karun., 2025

Du, Tian-Ye, Karunarathna, Samantha C., Hyde, Kevin D., Nilthong, Somrudee, Mapook, Ausana, Dai, Dong-Qin, Rajeshkumar, Kunhiraman C., Elgorban, Abdallah M., Han, Li-Su, Wang, Hao-Han & Tibpromma, Saowaluck, 2025, New Aquilariomyces and Mangifericomes species (Pleosporales, Ascomycota) from Aquilaria spp. in China, MycoKeys 112, pp. 103-125 : 103-125

Aquilariomyces maomingensis T. Y. Du, K. D. Hyde, Tibpromma & Karun. sp. nov.

Fig. 3

Etymology.

Named after the location “ Maoming, ” where the holotype was collected.

Holotype.

MHZU 23-0022 .

Description.

Saprobic on decaying branch of Aquilaria sinensis . Sexual morph: Ascomata (excluding necks) 250–450 μm high × 200–500 μm diam. (x ̄ = 366 × 350 μm, n = 5), solitary or gregarious in small groups, brown to dark brown, surrounded by short brown to black fluffs, immersed, slightly raised under the bark, globose to subglobose, sometimes ovoid, ostiolate. Ostiolar canal 250–280 µm long × 150–200 µm wide (x ̄ = 263 × 180 µm, n = 10), cylindrical to elliptical, usually straight, dark brown to black necks with periphyses. Peridium 15–70 μm (x ̄ = 31 μm, n = 30) wide, comprising 3–5 layers of pale brown to brown cells of textura angularis to textura prismatica, fusing with the host tissue. Hamathecium comprising 1 μm wide, hyaline, septate, branched, numerous, trabeculate pseudoparaphyses (sensu Liew et al. 2000), embedded in a gelatinous matrix. Asci 100–140 × 21–25 μm (x ̄ = 123 × 23 μm, n = 30), bitunicate, 8 - spored, thick-walled, clavate, apically rounded, with an ocular chamber, short pedicel, some club-shaped. Ascospores 20–36 × 9–15 μm (x ̄ = 30 × 13 μm, n = 30), uniseriate, 1 - septate, fusiform to ellipsoidal, conical at both ends or round, constricted at the septum, upper cells are slightly larger than below cells, rough-walled, with several guttules and granules, hyaline to pale yellow when immature and surrounded by a mucilaginous sheath, later become yellow-brown and without a mucilaginous sheath. Asexual morph: Undetermined.

Culture characteristics.

Ascospores germinated on PDA after 12 hours, and germ tubes were produced from one or both ends. Colonies on PDA reaching 2–3 cm diam. after two weeks at 23–28 ° C. Colonies obverse: dense, circular, or irregular, cream to brown, umbonate, raised at the center, filamentous edge. Colonies reverse dark brown to black at the center and cream to light brown at the margin.

Material examined.

China • Guangdong Province, Maoming City, Dianbai District, Poxin Town , 21°34'25"N, 111°7'43"E, on a dead branch of Aquilaria sinensis ( Thymelaeaceae ), 3 June 2022, T. Y. Du, MMA 15 ( MHZU 23-0022 , holotype), ex-type living culture, GMBCC 1047 ; additional living culture, ZHKUCC 23-0041 .

GenBank numbers.

GMBCC 1047: ITS = PQ 604643, LSU = PQ 604620, SSU = PQ 604624, tef 1 - α = PQ 612415, rpb 2 = PQ 612419; ZHKUCC 23-0041 : ITS = PQ 604644, LSU = PQ 604621, SSU = PQ 604625, tef 1 - α = PQ 612416, rpb 2 = PQ 612420.

Notes.

In the present phylogenetic analyses, our new collection, Aquilariomyces maomingensis , formed a well-separated sister lineage to Aq. aquilariae ( ZHKUCC 23-0072 and GZCC 23-0616 ) with 100 % ML and 1.00 BYPP statistical support (Fig. 2 ). Aquilariomyces maomingensis shares similar morphological characteristics with Aq. aquilariae ( MHZU 23-0036 , holotype) in having immersed, globose to subglobose ascomata, numerous, septate, branched, trabeculate pseudoparaphyses in a gelatinous matrix, clavate asci, with short and club-shaped pedicel, and uniseriate fusiform to ellipsoidal, 1 - septate, ascospores, constricted at the septum, and surrounded by a mucilaginous sheath ( Du et al. 2024 b). However, Aq. maomingensis ( MHZU 23-0022 ) differs from Aq. aquilariae ( MHZU 23-0036 ) in its ascomata and ascospore characters. Aquilariomyces maomingensis has ascomata surrounded by short fluffs, slightly raised under the bark, and brown mature ascospores, while Aq. aquilariae ( MHZU 23-0036 ) has inconspicuous ascomata, surrounded by long fluffs, and hyaline mature ascospores ( Du et al. 2024 b). A comparison of the main morphological structures between Aquilariomyces maomingensis and Aq. Aquilariae is shown in Fig. 4 .

According to the phylogenetic analysis of the present study, both Aquilariomyces species clustered in Thyridariaceae , a family characterized by trabeculate or cellular pseudoparaphyses. Trabeculate pseudoparaphyses are characterized by narrow, thread-like, apparently nonseptate, branched, and anastomosing or unbranched above the asci and embedded in a gelatinous matrix ( Liew et al. 2000; Hongsanan et al. 2020). This type of pseudoparaphyses is found in Aquilariomyces (Fig. 3 I ). Trabeculae were considered important at the Dothideomycetes O. E. Erikss. & Winka in earlier classifications; thus, Melanommatales was defined as having trabeculae ( Barr 1983). However, Liew et al. (2000) showed that trabeculae were not important at the order level and probably were important at the family level (or even species). Thyridariaceae comprises nine genera: Aquilariomyces , Chromolaenomyces Mapook & K. D. Hyde , Cycasicola Wanas., E. B. G. Jones & K. D. Hyde , Liua Phookamsak & K. D. Hyde , Parathyridaria Jaklitsch & Voglmayr , Parathyridariella Prigione, A. Poli, E. Bovio & Varese , Pseudothyridariella Mapook & K. D. Hyde , Thyridaria Sacc. , and Thyridariella Devadatha, V. V. Sarma, K. D. Hyde, Wanas. & E. B. G. Jones ( Wijayawardene et al. 2022; Du et al. 2024 b). Among these genera, Aquilariomyces ( Du et al. 2024 b) , Parathyridaria ( Jaklitsch and Voglmayr 2016) , and Thyridaria ( Jaklitsch and Voglmayr 2016) have trabeculate pseudoparaphyses; Chromolaenomyces ( Mapook et al. 2020) , Pseudothyridariella ( Mapook et al. 2020) , and Thyridariella ( Devadatha et al. 2018) have cellular pseudoparaphyses, while pseudoparaphyses of this type have not been reported yet in other genera, viz. Cycasicola , Liua , and Parathyridariella . We believe pseudoparaphyses type is one of the important characters at the genus level.

The base pair differences in the LSU, ITS, SSU, tef 1 - α, and rpb 2 genes (without gaps) between our new collection and Aq. aquilariae ( ZHKUCC 23-0072 , ex-type) were also compared. The results showed that there are 3.1 % nucleotide differences (28 / 912 bp) in LSU; in comparison, ITS has 12.3 % nucleotide differences (67 / 544 bp), SSU has 0.3 % nucleotide differences (3 / 873 bp), tef 1 - α has 7.5 % nucleotide differences (76 / 1008 bp), and rpb 2 has 10.6 % nucleotide differences (109 / 1025 bp). These comparisons indicate minor differences in SSU and LSU, while there are considerable base differences in ITS, tef 1 - α, and rpb 2. Therefore, we introduce our new collection as a new species, Aq. maomingensis , based on a polyphasic approach, according to the guidelines of Maharachchikumbura et al. (2021). Aquilariomyces maomingensis , the second Aquilariomyces species, was collected from the same host genus and country ( Aquilaria sinensis , China) as the first.

Figures

Figure 2. Phylogram generated from maximum likelihood (ML) analysis based on combined LSU, ITS, SSU, tef 1 - α, and rpb 2 sequence data of 52 taxa, which comprised 4387 base pairs of LSU = 967, ITS = 516, SSU = 872, rpb 2 = 1024, tef 1 - α = 1008. The best-scoring RAxML tree with a final likelihood value of - 31596.745436 is presented. The matrix had 2090 distinct alignment patterns, with 47.13 % of undetermined characters or gaps. Estimated base frequencies were as follows: A = 0.249245, C = 0.257277, G = 0.271627, T = 0.221851; substitution rates: AC = 1.210949, AG = 2.948777, AT = 1.318881, CG = 0.897105, CT = 6.444599, GT = 1.0; gamma distribution shape parameter α = 0.441696. Bootstrap support values for ML equal to or greater than 70 % and clade credibility values equal to or greater than 0.90 from Bayesian inference analysis are labelled at each node. The tree is rooted with Trematosphaeria pertusa (CBS 122368). The new isolates are indicated in red, and the ex-type strains are in bold.

Figure 3. Aquilariomyces maomingensis (MHZU 23-0022, holotype) A – C appearance of ascomata on the host (the arrows indicate ascomata) D, E vertical sections through the ascomata (the arrows indicate ostioles) F ostiole with periphyses G short fluffs around the periphery of the ascomata H peridium I, J trabeculae pseudoparaphyses (J the arrows indicate septate pseudoparaphyses) K – N asci O a club-shaped pedicel P – U ascospores (S stained with Indian ink) V germinated ascospore W, X colonies on PDA obverse and reverse views. Scale bars: 200 µm (D – F); 30 µm (G, H); 10 µm (I); 50 µm (K – N); 20 µm (P – V).

Figure 4. Comparison of morphological structure between Aquilariomyces maomingensis and Aq. aquilariae. Aquilariomyces maomingensis (MHZU 23-0022 holotype) A ascomata wrapped in short fluffs B micrograph of fluffs C brown ascospores. Aquilariomyces aquilariae (MHZU 23-0036, holotype) (Du et al. 2024 b) D ascomata wrapped in long fluffs E micrograph of fluffs F hyaline ascospores. Scale bars: 20 µm (B, C, E, F).