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

MFLU 18-2586.

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 4^th 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.

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.

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.

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.