Melomastia oleae W. L. Li, Maharachch. & Jian K. Liu

Bundhun, Digvijayini, Jones, E. B. Gareth, Jayawardena, Ruvishika S., Camporesi, Erio, Wanasinghe, Dhanushka N., Senanayake, Indunil C., Thiyagaraja, Vinodhini & Hyde, Kevin D., 2024, Taxonomic novelty in Pleomonodictydaceae and new reports for Ampelomyces quisqualis (Phaeosphaeriaceae), Melomastia maolanensis and M. oleae (Pleurotremataceae), MycoKeys 111, pp. 147-180 : 147-180

Melomastia oleae W. L. Li, Maharachch. & Jian K. Liu , Journal of Fungi 8 (1, no. 76): 10 (2022)

Fig. 7

Description.

Saprobic on dead branches of Duranta erecta . Sexual morph: Ascomata 415–420 µm high, 500–520 µm diam. (x – = 418.9 × 511.1 µm, n = 5), visible as black, cone-shaped structures on host surface, usually solitary, scattered, semi-immersed to erumpent, globose to ampulliform, carbonaceous, dark brown to black, ostiolate. Ostiole central, dark brown to black, papillate, carbonaceous, periphysate. Peridium 18–35 µm diam., comprising two regions in vertical section; outer region carbonaceous, made up of 5–7 - layered, thick-walled, brown cells of textura angularis to textura epidermoidea, innermost region composed of compressed, hyaline cells. Pseudoparaphyses 1.5–2.5 µm wide, numerous, filiform, unbranched, sometimes septate. Asci 100–180 × 5.5–8 µm (x – = 142.7 × 6.7 µm, n = 22), 8 - spored, non fissitunicate, cylindrical, straight to flexuous, rounded at the apex, with a small ocular chamber, short-pedicellate. Ascospores 20–25 × 5–6 µm (x – = 22.2 × 5.5 µm, n = 30), uniseriate, hyaline, fusiform, with rounded or obtuse ends, 3 - septate, slightly constricted at the septa, guttulate, smooth-walled. Asexual morph: Not observed.

Culture characteristics.

Colonies on PDA reaching 20 mm diam. in 3 weeks at 25 ° C. Culture from above circular, regular, entire margin, dense, white; reverse pale brown.

Material examined.

Thailand • Chiang Rai, Mae Fah Luang University, Mueang, Tha Sut ; on dead stems and twigs of Duranta erecta , 30 Nov 2021, V. Thiyagraja DB 184, Herbarium material MFLU 23-0144 , living culture MFLUCC 23-0086 .

Notes.

The isolate MFLUCC 23-0086 in the present study is basal to all the strains of M. oleae (Fig. 3 ). There was 0.2 % (2 / 986 bp) nucleotide difference in SSU, while 0.9 % (8 / 872 bp) in LSU and 0.1 % (1 / 894 bp) in tef 1 - α between strain MFLUCC 23-0086 and the type strain (CGMCC 3.20619) of M. oleae . Isolate MFLUCC 23-0086 is morphologically similar to M. oleae in terms of ascomata which appear as cone-shaped on the host surface, filiform and unbranched pseudoparaphyses, cylindrical, pedicellate asci and uniseriate, fusiform, 3 - septate ascospores. However, the asci and ascospore sizes of the type of M. oleae are larger than our collection. Furthermore, the peridium of strain MFLUCC 23-0086 is observed as comprising thick-walled, brown cells of textura angularis to textura epidermoidea in the outer region and compressed, hyaline cells in the innermost region (Fig. 7 ). The type of M. oleae is reported to have a peridium with an outer thick, carbonaceous layer and the inner one made up of 5–6 layers of hyaline cells of textura angularis to textura prismatica ( Li et al. 2022). Despite these morphological differences, MFLUCC 23-0086 is recognized as M. oleae as there is insufficient genetic variation to distinguish it as a different species ( Maharachchikumbura et al. 2021; Pem et al. 2021). Furthermore, the morphological differences may be due to different hosts and environmental conditions. Therefore, M. oleae is herein introduced as a new record from Duranta erecta in Thailand.

Figures

Figure 3. Phylogram generated from maximum likelihood RaxML analysis based on combined SSU, LSU, and tef 1 - α sequence data. The evolutionary model SYM + I + G was chosen as the best-fit model for SSU while GTR + I + G was applied for LSU and tef 1 - α. The BYPP analysis was run for 2 million generations. The tree is artificially rooted with Anisomeridium phaeospermum (MPN 539) and A. ubianum (MPN 94). Maximum likelihood bootstrap, ML BS (≥ 60 %), and BYPP (≥ 0.95) are given respectively above or below the branches. Type strains are in bold. The newly generated sequences are indicated in bold red. (-) indicates ML BS < 60 % or BYPP < 0.95. TreeBASE submission ID: 31445.

Figure 7. Melomastia oleae (MFLU 23-0144) a ascomata on the stem of Duranta erecta b an ascoma erumpent through the host tissue c vertical section of an ascoma d peridium e pseudoparaphyses f – h asci i – k ascospores. Scale bars: 200 µm (c); 20 µm (d, i – k); 5 µm (e); 30 µm (f – h).