Pseudoberkleasmium chiangraiense X. G. Tian & Tibpromma 2022, sp. nov.

Abstract

<i>Pseudoberkleasmium chiangraiense</i> X.G. Tian & Tibpromma, <i>sp. nov.</i> (FIGURE 3) <p>Index Fungorum number: IF 558909; Facesoffungi number: FoF 10572</p> <p> <b>Etymology:—</b> Referring to Chiang Rai Province, Thailand, where the species was first collected.</p> <p> <b>Holotype:</b> MFLU 21–0291</p> <p> <i>Saprobic</i> on dead leaves of <i>Cocos nucifera</i> L. <b>Sexual</b> <b>morph</b> Undetermined. <b>Asexual morph</b> Hyphomycetous. <i>Colonies</i> on natural substrate, superficial, in groups, scattered, black, velvety, glistening, with conidia readily liberated when disturbed. <i>Mycelium</i> immersed in the substrate, composed of septate, branched, smooth, hyaline to pale brown hyphae. <i>Conidiophores</i> micronematous, mononematous, hyaline, smooth. <i>Conidiogenous cells</i> 9–13 × 11–13 μm (x̅ = 10.5 × 12.0 μm, n = 20), holoblastic, monoblastic, determinate, terminal, globose to subglobose or cup-shaped, integrated, connected at the base of conidia, smooth, guttulate, hyaline. <i>Conidia</i> 26–30 × 14–17.5 μm (x̅ = 28 × 15.5 μm, n = 50), acrogenous, solitary, ellipsoidal to obovoid, flattened, muriform, smooth-walled, dark brown to black at apical, pale brown at basal, guttulate, usually with a smooth hyaline conidiogenous cell attached.</p> <p> <b>Culture characteristics:—</b> Conidia germinating on PDA within 12 hr at 25 °C, not sporulating after two months. Surface with hyphal growth, circular, umbonate, fluffy, White at the margin, dark brown to black at the middle; reverse white to pale brown at the margin, black at the middle. Mycelium superficial, circular, partially immersed, hyaline to brown, smooth.</p> <p> <b>Material examined</b>:— THAILAND, Chiang Rai Province, Muang District, on decaying leaves of <i>Cocos nucifera</i> (Arecaceae), 8 December 2020, X. G. Tian, C4–1 (MFLU 21–0291, <b>holotype</b>), ex-type culture, MFLUCC 21–0154; <i>ibid.</i> 16 January 2021, C6–7 (MFLU 21–0292, paratype), living culture, MFLUCC 21–0161; <i>ibid.</i> C6–23 (MFLU 21–0293, paratype), living culture, MFLUCC 21–0162.</p> <p> <b>Notes:—</b> In the phylogenetic analyses, our new strains of <i>Pseudoberkleasmium chiangraiense</i> (MFLUCC 21–0154, MFLUCC 21–0161 and MFLUCC 21–0162) clustered as a sister clade to <i>P. chiangmaiense</i> (MFLUCC 17–2088, MFLUCC 17–1809 and MFLU 21–0290) with a 76% ML bootstrap support value (FIGURE 1). Our new isolate <i>Pseudoberkleasmium chiangraiense</i> (MFLUCC 21–0154) resembles <i>P. pandanicola</i> in having micronematous, mononematous conidiophores and muriform, ellipsoidal to obovoid, flattened guttulate conidia. However, our new isolate (MFLUCC 21–0154) differs from <i>P. pandanicola</i> by its conidia that are dark brown to black at the apex and pale brown at the base, while <i>P. pandanicola</i> has brown to olivaceous green conidia (Tibpromma <i>et al.</i> 2018). Our new isolate <i>Pseudoberkleasmium chiangraiense</i> (MFLUCC 21–0154) morphologically differs from <i>P. chiangmaiense</i> by the colour of conidia (dark brown to black at apical, pale brown at basal vs. yellow to brown) and smaller size (25.5– 30.0 vs. 30–35 μm) (Hyde <i>et al.</i> 2019). The nucleotide comparisons revealed that the new strain (MFLUCC 21–0154) is different from <i>P. pandanicola</i> (KUMCC 17–0178) in 15/367 bp (4.09%) of the ITS, and 8/848 (0.94%) of the LSU, while, the new strain (MFLUCC 21–0154) is different from <i>P. chiangmaiense</i> (MFLUCC 17–1809 ex-type) in 15/389 bp (3.86%) of the ITS, 6/840 (0.71%) of the LSU, and 49/899 bp (5.45%) of TEF1-α.</p> <p> Taxa in <i>Pseudoberkleasmium</i> have similar morphological characteristics with <i>Berkleasmium</i>, however, they are distinct in phylogenetic analyses. <i>Berkleasmium nigroapicale</i> and <i>B. sutheppuiense</i> were introduced from Chiang Mai, Thailand, while our new species was collected in Chiang Rai, Thailand that is geographically not too far. However, <i>Berkleasmium nigroapicale</i> and <i>B. sutheppuiense</i> lack molecular data, thus, we compared the morphology of our new species with <i>B. nigroapicale</i> and <i>B. sutheppuiense</i> and found that <i>B. nigroapicale</i> differs from <i>P. chiangraiense</i> in having cylindrical and clavate conidiogenous cells, and broadly clavate conidia (Bussaban <i>et al.</i> 2001). While, <i>B. sutheppuiense</i> differs from our new species in having cylindrical conidiogenous cells with subglobose and very dark brown conidia (Bussaban <i>et al.</i> 2001). Thus, we identified the three new isolates as a distinct new species of <i>Pseudoberkleasmium</i>.</p>Published as part of <i>Tian, Xingguo, Tibpromma, Saowaluck, Karunarathna, Samantha C., Dai, Dongqin, Lu, Yongzhong, Mapook, Ausana & Jayawardena, Ruvishika S., 2022, A new species and a new host record of Pseudoberkleasmium (Pseudoberkleasmiaceae, Dothideomycetes) from Cocos nucifera and Zea mays in northern Thailand, pp. 232-242 in Phytotaxa 547 (3)</i> on page 239, DOI: 10.11646/phytotaxa.547.3.2, <a href="http://zenodo.org/record/6577519">http://zenodo.org/record/6577519</a&gt