Linocarpon bambusina X. Zhang & Tibpromma, 2023

Zhang, Xian, Dai, Dongqin, Du, Tianye, Karunarathna, Samantha C. & Tibpromma, Saowaluck, 2023, Morpho-phylogeny characterization of Linocarpon bambusina sp. nov. (Linocarpaceae, Chaetosphaeriales) associated with bamboo in Yunnan Province, China, Phytotaxa 584 (2), pp. 89-103 : 95-97

Linocarpon bambusina X. Zhang & Tibpromma , sp. nov. ( Fig. 2 )

Index Fungorum number: IF900063; Facesoffungi number: FoF 12953

Holotype: GMB1360

Etymology: Species epithet refers to the host genus “ bambusa ” from which the holotype was collected.

Saprobic on dead culms of bamboo. Sexual morph: Ascomata 150–330 × 360–560 μm (x = 223.5 × 484 μm, n = 10), solitary or aggregated, mostly aggregated, semi-immersed, black, shiny, dome-shaped, raised, subglobose, flattened at the base, central ostiole with papillate. Ostiole periphysate, carbonaceous. Peridium 15–50 μm wide (x = 32 μm, n = 10), outer cells merging with the host epidermal cells, composed of brown to dark brown cells of textura angularis. Hamathecium 2.5–6 µm wide (x = 4 μm, n = 20), hyaline, hypha-like, septate paraphyses. Asci 75–140 × 9–20 μm (x = 105 × 12 μm, n = 50), 8-spored, unitunicate, long fusiform, shortly pedicellate, furcate pedicel, with a J- subapical ring. Ascospores 65–100 × 2–6 μm (x = 87 × 4.5 μm, n = 50), fasciculate, filiform, straight or curved, hyaline, 28–30 septa, parallel when immature and becoming spiral when mature in asci, with guttules when immature, ends slightly rounded, without appendage or mucilaginous sheath, smooth-walled. Asexual morph: Undetermined.

Culture characteristics: Ascospores germinated on PDA within 24 h, and cultured at 25–28 ˚C after one month, pure mycelia flossy, curled, colonies, circular, umbonate, white to pale brown in above, the reverse side is brown in the middle and yellow-white at the margin.

Material examined: China, Yunnan Province, Lijiang City , on dead bamboo culms, 13 July 2021, D.Q. Dai, DDQ02097 (holotype, GMB 1360 ; isotype, KUN-HKAS 125776 ; ex-type living culture, GMBCC 1155).

Notes: In the phylogenetic tree, our new species Linocarpon bambusina formed a well-separated clade sister to L. pandanicola (HKUCC3783, HKUCC 4385, HKUM16280) with moderate bootstrap support (55% ML) ( Fig. 1 ). The comparison of LSU nucleotides between our taxon and L. pandanicola (HKUCC 4385) resulted in 8.1% difference (65/800 bp, without gaps), but L. pandanicola did not have SSU and tef 1-α genes to compare with L. bambusina . Linocaropn bambusina can be distinguished from L. pandanicola by having shiny ascomata, ostiolar papillate, fusiform asci with club shape, ascospores with 28–30 septa, and no appendages or mucilaginous sheath, while these characteristics are not present in L. pandanicola . In addition, our taxon and L. arengae are similar in asci pedicellate with a J- subapical ring, and filiform ascospores with straight or curved but can be distinguished by having semi-immersed ascomata, fusiform asci, ascospores with 28–30 septa, not constricted at septa, guttules, and no appendages or mucilaginous sheath, while L. arengae has immersed ascomata, cylindrical asci, aseptate ascospores, containing numerous refringent septum-like bands with polar mucilaginous appendage at the apex ( Konta et al. 2017). Finally, L. bambusina can be distinguished by having solitary or aggregated, mostly aggregated, shiny, semi-immersed ascomata, with a J- subapical ring asci, ascospores with 28–30 septa, without appendage or mucilaginous sheath, while L. bambusicola has gregarious, superficial, ascomata, asci non-amyloid ring, aseptate ascospores, and the basal end sometimes with 1–3 minute mucilaginous drops ( Cai et al. 2004). In addition, our new species is distinguished morphologically by its relatively semi-immersed ascomata, 28–30 septate ascospores, and no appendages or mucilaginous sheath, which is different from other species in Linocarpon .

Figures

FIGURE 1. RAxML tree based on a combined dataset of LSU, SSU, and tef1-α gene sequences. Bootstrap support values for maximum likelihood (ML) equal to or higher than 50% and bayesian posterior probability (BYPP) equal to or higher than 0.90 are indicated above the branches. Newly generated sequences are shown in red, while the ex-type species are shown in bold black.

FIGURE 2. Linocarpon bambusina (GMB1360, holotype) a–c. Appearance of ascomata on host substrate. d. Section of an ostiole. e. Section of an ascoma. f. Peridium. g–j. Asci (i, j stained by Cotton blue reagent). k. Club-shaped pedicel stained by lactophenol cotton blue reagent. l. Ascus apical tip stained by Melzer’s reagent. m. Paraphyses. n–s. Ascospores (o, r, s stained by lactophenol cotton blue reagent). t. A germinating ascospore. u, v. Colonies on PDA from above and below after one month. Scale bars: d, e = 200 μm; f, k = 20 μm; g–j = 50 μm; l, m = 20 μm; n–s = 50 μm.