Racheliella chinensis Y.X. Zhang, J.Y. Lin & Manawas., sp. nov.

Index Fungorum number: IF 902393; Mycobank number: MB 902393; Facesoffungi number: FoF 16059; Fig. 1

Etymology – Referring to the country name China

Holotype – MHZU 22-0172

Associated with leaf spot of Livistona chinensis. Sexual morph: not observed. Asexual morph: Produced on 14 days old PDA culture. Conidiophores often reduced to conidiogenous cells. Conidiogenous cells 5–14×1–3.5 (x̅=9.1×2.3, n=50), hyaline, phialidic to doliform, thin-walled, smooth. Conidia 8–15×3–5(x̅=11.6×4.1, n=50), hyaline, aseptate, mostly ovoid, occasionally fusiform, with a rounded apex and narrowly truncate to pointed base, thin-walled, smooth.

Culture characteristics – Colonies growing slowly at 25 °C on MEA, circular, fluffy, with regular edge, aerial mycelium initially white, gradually becoming grey after 14 days, reverse initially light brown, becoming dark brown after 14 days.

Material examined – China, Guangdong Province, Shenzhen, on leaves of Livistona chinensis (Palmae), 30 November 2020, C.T. Chen (MHZU 22-0172, holotype), ex-type culture ZHKUCC 22-0330.

GenBank number – ITS=PP851442, PP849415, tef1-α=PQ219689, PQ219690, tub2=PQ219691, PQ219692

Notes – In the phylogeny (Fig. 2), two isolates from Racheliella chinensis clustered into a distinct clade with 0.99 in BYPP support sister to R. wingfieldiana. Our isolate differs from R. wingfieldiana and R. saprophytica in having narrow conidia (8–15×3–5 vs. 12–14×7 vs currently 46 accepted species 9–15×5–6 μm). The nucleotide of our strain (ZHKUCC 22-0330) differs from R. wingfieldiana (CBS 143669) by 17.53% (102/582) variations in ITS, 34.40% (218/623) variations in tef 1-α and 24.47% (127/519) variations in tub2, differs from R. saprophytica (NTCL 052-1) by 10.09% (54/535) variations in ITS (tef1-α and tub2 not available in R. saprophytica). Thus, we introduced Racheliella chinensis as a new species based on morphology and phylogenetic evidence.

Figure 1 – Racheliella chinensis (ZHKUCC 22-0330, holotype) a Colonies on MEA (7 d). b Colonies on MEA (14 d). c, d Conidiogenous cells. e, f Conidia. Scale bars: c–d=10 μm

Figure 2 – Phylogenetic tree of Racheliella species based on maximum likelihood (ML) analyses of the combined DNA dataset of ITS, tef1-α and tub gene sequences. The ML bootstrap support values≥75% and BYPP higher than 0.95 are indicated above the nodes and branches. The scale bar indicates 0.05 changes per site. Extype strains are marked in bold. Isolates of novel taxa are in red in this study. The tree is rooted with Melanconis groenlandica (CBS 143669)

Figure 2 – (continued)