Phaeosphaeriopsis beaucarneae Tennakoon, C.H. Kuo & K.D. Hyde, 2020

Tennakoon, Danushka S., Thambugala, Kasun M., Wanasinghe, Dhanushka N., Gentekaki, Eleni, Promputtha, Itthayakorn, Kuo, Chang-Hsin & Hyde, Kevin D., 2020, Additions to Phaeosphaeriaceae (Pleosporales): Elongaticollum gen. nov., Ophiosphaerella taiwanensis sp. nov., Phaeosphaeriopsis beaucarneae sp. nov. and a new host record of Neosetophoma poaceicola from Musaceae, MycoKeys 70, pp. 59-88 : 59

Phaeosphaeriopsis beaucarneae Tennakoon, C.H. Kuo & K.D. Hyde sp. nov. Figures 4 , 5

Etymology.

Name reflects the host Beaucarnea recurvata Lem., from which the holotype was collected.

Holotype.

MFLU 18-2586.

Diagnosis.

Saprobic on dead leaf of Beaucarnea recurvata Lem. ( Asparagaceae ). Sexual morph: Ascomata 160-200 μm high, 220-250 μm diam., scattered, solitary, gregarious, coriaceous, immersed to semi-immersed, slightly raised, erumpent, visible as black spots on host surface, uniloculate, dark brown to black, globose to subglobose, ostiolate. Ostiole central, papillate. Peridium 20-30 μm wide, thick-walled, of equal thickness, composed of 4-5 layers of dark brown to brown, thick-walled, pseudoparenchymatous cells of textura angularis. Hamathecium of 1.5-2.5 µm wide, cellular, septate, rarely branching, pseudoparaphyses, anastomosing mostly above the asci and embedded in a mucilaginous matrix. Asci 80-90 × 9-10 µm (x̄ = 86.5 × 9.6 µm, n = 25), 8-spored, bitunicate, fissitunicate, cylindrical to cylindric-clavate, short pedicellate, apically rounded, with a well-developed ocular chamber. Ascospores 20-25 × 5.5-7 μm (x̄ = 22.6 × 6.2 μm, n = 20), overlapping 1-2-seriate, oblong to cylindrical, yellowish to light brown, slightly narrowing towards the end cells, mostly 5-septate, constricted at the septa, enlarged at the 4th cell from above, verruculose, straight to curved, lacking a mucilaginous sheath. Asexual morph: Conidiomata 180-200 µm high, 140-160 µm diam., pycnidial, solitary, immersed to erumpent, small black spots on host surface, globose to subglobose with centrally placed ostiole. Conidiomatal wall 28-34 µm wide, composed of 6-7 layers of dark brown cells, arranged in textura angularis. Conidiophores reduced to conidiogenous cells. Conidiogenous cells 3-4 × 2.6-3.1 μm, holoblastic, phialidic, single, discrete, sometimes integrated, ampulliform or cylindric-clavate, hyaline, arising from basal stratum. Conidia 6.8-7.4 × 3-4 μm (x̄ = 7.1 × 3.4 μm, n = 30), 1-celled, globose to subglobose, initially hyaline, becoming brown to dark brown, aseptate, rough-walled.

Culture characteristics.

Colonies on PDA reaching 27 mm diameter after 3 weeks at 20-25 °C, colonies medium sparse, circular, raised, surface slightly rough with entire edge, margin irregular, colony from above: light brown at the margin, white to cream at the center; reverse, yellow to light brown at the margin, light brown to brown at the center; mycelium white to cream with tufting; not producing pigments in PDA.

Material examined.

Taiwan, Chiayi, Fanlu Township area, Dahu Forest, dead leaf of Beaucarnea recurvata Lem. ( Asparagaceae ), 21 July 2018 (23°27.514'N, 120°36.302'E), D.S. Tennakoon, SV027 (MFLU 18-2586, holotype); ibi. (NCYU19-0184, isotype), ex-type living culture, NCYUCC 19-0106; ibid., Dahu forest, dead leaf of Beaucarnea recurvata Lem. ( Asparagaceae ), 25 July 2018 (23°26.534'N, 120°36.220'E), D.S. Tennakoon, SV028 (MFLU 18-2587, paratype); living culture, NCYUCC 19-0107.

Notes.

Phaeosphaeriopsis beaucarneae is similar to other Phaeosphaeriopsis species in having scattered, semi-immersed to erumpent, globose to subglobose, ostiolate ascomata and cylindrical to clavate asci and light brown, verrucose ascospores ( Phookamsak et al. 2014; Thambugala et al. 2014; Hyde et al. 2020). According to the present multi-gene phylogenetic analyses (Figure 1 ), Phaeosphaeriopsis beaucarneae is grouped with other Phaeosphaeriopsis species, in particularly closely to P. grevilleae (CBS 145369) with high statistical support (70% ML, 75% MP, 0.99 BYPP, Figure 1 ). The asexual morph of P. grevilleae was isolated from leaves of Grevillea sp. ( Proteaceae ) and introduced by Marin-Felix et al. (2019). Phaeosphaeriopsis beaucarneae differs from P. grevilleae in having larger conidia (6.8-7.4 × 3-4 μm), whereas P. grevilleae has comparatively smaller conidia (5 × 3.5 μm). A comparison of the 516 nucleotides across the ITS (+5.8S rDNA) gene region of Phaeosphaeriopsis beaucarneae and P. grevilleae (CBS 145369) revealed 16 base pair differences (3.10%). In addition, we compared our new taxon with P. grevilleae based on base pair differences in the tef1 -α gene region. We found a total of 19 base pair differences (3.06%) across 619 nucleotides.

Recent studies have revealed that Phaeosphaeriopsis is a species rich genus and numerous Phaeosphaeriopsis species have been described during the last few years ( Thambugala et al. 2014; Tibpromma et al. 2017; Marin-Felix et al. 2019; Al-Jaradi et al. 2020; Hyde et al. 2020). With this study, the number of Phaeosphaeriopsis species increases to 18.

Figures

Figure 1. RAxML tree inferred from combined dataset of ITS, LSU, SSU and tef 1 - α partial sequences of 168 strains of Phaeosphaeriaceae. Bootstrap support values for maximum likelihood (ML), maximum parsimony (MP) values ≥ 70 %, and Bayesian posterior probabilities (BYPP) ≥ 0.95 are given above each branch respectively. The new species are highlighted in red, and the new record in green. Ex-type strains are in bold. The tree is rooted by Leptosphaeria doliolum (CBS 505.75) and Paraleptosphaeria dryadis (CBS 643.86).

Figure 4. Phaeosphaeriopsis beaucarneae (MFLU 18 - 2586, holotype) a appearance of ascomata on host b close up of ascoma c vertical section through ascoma d peridium e pseudoparaphyses f-i asci j-n ascospores o germinated ascospore in PDA p colony from above q colony from below. Scale bars: 100 µm (c), 15 µm (d), 50 µm (e-i), 10 µm (j-o).

Figure 5. Phaeosphaeriopsis beaucarneae (MFLU 18 - 2586, paratype) a appearance of conidiomata on host b close up of conidiomata c vertical section through conidioma d conidiomatal wall e, f conidiogenous cells and developing conidia g-i conidia j germinated conidium in PDA k colony from above l colony from below. Scale bars: 100 µm (c), 20 µm (d), 3 µm (e, f), 5 µm (g-j).