Byssosphaeria siamensis Boonmee, Q. Tian & K. D. Hyde

Tennakoon, Danushka S., Thambugala, Kasun M., de Silva, Nimali I., Song, Hai-Yan, Suwannarach, Nakarin, Chen, Fu-Sheng & Hu, Dian-Ming, 2024, An overview of Melanommataceae (Pleosporales, Dothideomycetes): Current insight into the host associations and geographical distribution with some interesting novel additions from plant litter, MycoKeys 106, pp. 43-96 : 43-96

Byssosphaeria siamensis Boonmee, Q. Tian & K. D. Hyde , Fungal Diversity 74: 283 (2015)

Fig. 6

Description.

Saprobic on dead stem of Citrus trifoliata L. ( Rutaceae ). Sexual morph: Ascomata 250–400 × 300–500 µm (x ̄ = 320 × 410 μm, n = 10), solitary to gregarious, superficial, dark brown to black, setose, coriaceous, unilocular, globose to subglobose, non-papillate, apex rounded with an orange to yellow ostiole, ostiole central, with pore-like opening. Peridium 20–35 μm wide, thick-walled, composed of several layers of dark brown cells, orange to yellow near ostiole, arranged in textura angularis to textura prismatica. Hamathecium 1–2.5 μm wide, comprising dense, filiform, anastomosing, septate, pseudoparaphyses, embedded in a gelatinous matrix. Asci 110–130 × 11–13 μm (x ̄ = 120 × 12 μm, n = 20), 8 - spored, bitunicate, fissitunicate, cylindrical clavate, apically rounded, long pedicellate (20–35 μm), with an ocular chamber. Ascospores 30–40 × 6.5–8 μm (x ̄ = 31 × 7 μm, n = 30), overlapping, 1–2 - seriate, ellipsoid to fusiform, initially hyaline, pale brown when mature, 1 - septate, constricted at the septum, slightly curved, smooth-walled or verrucose. Asexual morph: Undetermined.

Material examined.

China, Yunnan Province, Kunming , on a dead stem of Citrus trifoliata ( Rutaceae ), 27 July 2016, D. S. Tennakoon, KDS 27 ( HFJAU 10336 ) .

Known hosts.

Citrus trifoliata (this study).

Known distribution.

China, Thailand ( Tian et al. 2015; Hyde et al. 2018; this study).

Notes.

The morphological characteristics of our collection ( HFJAU 10336 ) similar to the type of Byssosphaeria siamensis in their superficial, dark brown to black, setose, non-papillate ascomata, cylindrical clavate asci and ellipsoid to fusiform, pale brown, 1 - septate ascospores ( Tian et al. 2015). In addition, both share overlapping size ranges of asci (110–130 × 11–13 μm vs. 112–148 × 10–16 μm) and ascospores (30–40 × 6.5–8 μm vs. 40.5–50 × 7–11 μm) ( Tian et al. 2015). However, our collection is lacking a mucilaginous sheath which is present in the type species ( Tian et al. 2015). According to the multi-gene phylogeny, our collection nested with By. siamensis isolates in 86 % ML and 0.98 BYPP supported clade and close to the isolate MFLUCC 17-1800 with 88 % ML, 0.99 BYPP support. Therefore, based on both morphology and phylogeny evidence, we introduce our collection as a new host record of B. siamensis from Citrus trifoliata in China.

Figures

Figure 6. Byssosphaeria siamensis (HFJAU 10336, new host record) a appearance of ascomata on the host b close-up of ascomata c vertical section of an ascoma d ostiole e peridium f pseudoparaphyses g, h asci i – m ascospores. Scale bars: 200 µm (c); 20 µm (d, e); 50 µm (f – h); 10 µm (i – m).