Pleopunctum baoshanense G. C. Ren & Tibpromma, 2024

Ren, Guang-Cong, Tibpromma, Saowaluck, Dong, Kai-Xuan, Gao, Chen-Xi, Zhang, Chao-Shan, Karunarathna, Samantha C., Elgorban, Abdallah M. & Gui, Heng, 2024, Unveiling fungi associated with Castanopsis woody litter in Yunnan Province, China: Insights into Pleosporales (Dothideomycetes) species, MycoKeys 108, pp. 15-45 : 15-45

Pleopunctum baoshanense G. C. Ren & Tibpromma sp. nov.

Fig. 7

Etymology.

The specific epithet “ baoshanense ” reflects the location “ Baoshan ” where the holotype was collected.

Holotype.

HKAS 134936.

Description.

Saprobic on decaying wood of Castanopsis calathiformis ( Fagaceae ) in terrestrial habitat. Sexual morph: Undetermined. Asexual morph: Hyphomycetous. Colonies on natural substrate sporodochial, superficial, black, scattered, gregarious. Mycelium immersed in the substratum, composed of septate hyphae. Conidiophores 3–5 µm wide (x ̄ = 3.8 µm, n = 15), macronematous, mononematous, cylindrical, unbranched, septate, hyaline and smooth-walled. Conidiogenous cells monoblastic, terminal, integrated, hyaline. Conidia 33–46 × 22.5–27.6 μm (x ̄ = 39 × 25 μm, n = 40), acrogenous, solitary, muriform, oval to ellipsoidal, smooth-walled, broadly obtuse at apex and dark brown, truncate at base and paler brown, often with a hyaline, elliptical to globose basal cell, 10–14 × 13–15 μm (x ̄ = 12 × 13 μm, n = 30).

Culture characteristics.

Conidia germinated on PDA within 24 h at room temperature (25 ° C). Germ tubes produced from the basal cells of conidia. Colonies on PDA, reaching 30 mm diameter after 2 weeks at 20–25 ° C, mycelia superficial, irregular, umbonate at the center, fimbriate, undulate entire, grey, radially furrowed, with hyaline, glistening, rough, wrinkled, granular droplets of oil; reverse, grey, radially furrowed, grey white at the margin.

Material examined.

China, Yunnan Province, Baoshan (25 ° 18 ' 48 " N, 99 ° 09 ' 50 " E), on dead woody twigs of Castanopsis calathiformis ( Fagaceae ), 12 July 2020, G. C. Ren, B 194 ( HKAS 134936 , holotype), ex-type living culture KUNCC 21-0494 .

Notes.

Multi-loci phylogenetic analyses based on a concatenated SSU, LSU, ITS, tef 1 - α, and rpb 2 sequence dataset show that our new collection (KUNCC 21-0494) clusters sister to strains of Pleopunctum pseudoellipsoideum (MFLUCC 19-0391, KUMCC 21-0820, HKAS 122915) and P. ellipsoideum (MFLUCC 19-0390, MFLUCC 21-0064) with solid support (100 % ML and 1.00 BYPP, Fig. 3 ). Sequence comparison for the ITS region between Pleopunctum baoshanense (KUMCC 21-0494) and P. pseudoellipsoideum (MFLUCC 19-0391) showed a 1.54 % (8 / 520 bp, without the gaps) base pair difference, 2.26 % (21 / 930 bp, without the gaps) base pair difference for the tef 1 - α region. Sequence comparison for the ITS region between Pleopunctum baoshanense (KUNCC 21-0494) and P. ellipsoideum (MFLUCC 19-0390) showed a 1.65 % (8 / 486 bp, without the gaps) base pair difference, 1.81 % (15 / 827 bp, without the gaps) base pair difference for tef 1 - α region. Pleopunctum baoshanense , P. pseudoellipticum , and P. ellipsoideum are morphologically similar, they have sporodochial conidiomata; septate hyphae mycelium; mononematous, cylindrical conidiophores; monoblastic, terminal, hyaline conidiogenous cells and muriform, oval to ellipsoidal conidia often with a hyaline, elliptical to globose basal cell, but can be distinguished from P. pseudoellipsoideum and P. ellipsoideum in having hyaline conidiophores and conidiogenous cells, different sizes of conidia (39 × 25 μm vs. 50 × 24 μm vs. 45 × 20 μm), while both of them have medium brown conidiophores and conidiogenous cells ( Liu et al. 2019; Xu et al. 2023). Therefore, based on morphology and phylogenetic distinctiveness, we introduce Pleopunctum baoshanense as a new species.

Figures

Figure 3. Phylogram generated from maximum likelihood analysis based on the combined SSU, LSU, ITS, tef 1 - α, and rpb 2 dataset of Phaeoseptaceae species. Related sequences were obtained from Xu et al. (2023). Bootstrap values for ML are equal to or greater than 75 %, and posterior probability values are equal to or greater than 0.95 from the BYPP analysis labelled on the nodes. Strains of the newly described species are in red, while type strains are in bold. The tree is rooted with Angustimassarina acerina (MFLUCC 14-0505) and A. populi (MFLUCC 13-0034).

Figure 7. Pleopunctum baoshanense (HKAS 134936, holotype) a host b colonies on the host surface c – f conidia with basal hyaline cells g germinated conidium h, i colony on PDA (h = from above, i = from below). Scale bars: 20 μm (c – g); 20 mm (h, i).