Lasiodiplodia morindae M. Luo & M.P. Zhao, sp. nov.

Index Fungorum number: IF 900421; MycoBank number: MB 900421; Facesoffungi number: FoF 14176; Fig. 1

Etymology – based on its host Morinda officinalis.

Endophytic on Morinda officinalis How. Sexual morph: Undetermined. Asexual morph: Paraphyses up to 30 μm long, 2–3 μm wide, filiform, hyaline, septate, cylindrical, arising from the inner layer of conidiomatal wall, ends rounded. Conidiophores reduced to conidiogenous cells. Conidiogenous cells holoblastic, hyaline, thinwalled, smooth, cylindrical. Conidia 20–30 × 10–20 μm (x=24±2×14±1 μm, n=50), initially hyaline, aseptate, becoming median, 1-septate, dark brown when mature, thick-walled, ellipsoid to obovoid with a round and slightly tapered apex, turning brown with one median septum when mature.

Culture characteristics – Colonies growing on PDA reached to 60 mm diam. after 2 days at 25 °C in the dark, initially white, fast growing, circular, raised, fluffy, filamentous, becoming grey after 5 days. Reverse white first and then turn to grey and dark grey.

Material examined – China, Guangdong Province, Zhaoqing City, healthy stem of Morinda officinalis (Rubiaceae), June 2020, W. Guo, (MHZU 22-0050, holotype); ex-type cultures, ZHKUCC 22-0084, ZHKUCC 22-0083.

GenBank numbers – ITS: ON603984, ON603985, β-tubulin: OP893932, OP893933.

Notes – The combined gene analyses of ITS, β-tubulin and tef1-α sequences (Fig. 2) showed that our isolates clustered with ex-type strain of Lasiodiplodia tropica (CGMCC 3.18477) with ML=78%, BI=0.90 bootstrap values. Morphologically, our strain has ellipsoid, thin-walled, larger conidia (x=24 × 15 μm) with one median septum while L. tropica has ellipso-ovoid to globose, small conidia (x=21×12 μm) with one supra-median septum or two septa (Wang et al. 2019a). The conidia of our strains take five weeks to become fully pigmented while L. tropica takes only about two weeks. The pigmentation schedule of conidia has been considered a significant feature for species identification in Lasiodiplodia (Dou et al. 2017). Therefore, we introduced this collection as Lasiodiplodia morindae sp. nov.

Figure 1 – Lasiodiplodia morindae (ZHKUCC 22-0084, ex-holotype). a Upper view of colony on PDA. b Reverse view of colony on PDA. c Pycnidium on PDA. d Conidiogenous cells with developing conidia. e–h Conidia (hyaline immature conidia, brown mature conidia). Scale bars: d–h=10 µm

Figure 2 – The best scoring RAxML tree for combined dataset of ITS, β-tubulin and tef1-α sequence data of Lasiodiplodia. The topology and clade stability of the combined gene analyses was compared to the single gene analyses and there was no significant difference between them. The tree is rooted to Diplodia mutila (CMW 7060). The matrix had 306 distinct alignment patterns with 13.19% undetermined characters and gaps. Estimated base frequencies were as follows; A=0.209302, C=0.309977, G=0.254177, T=0.226543; substitution rates AC=0.878409, AG=3.555855, AT=0.948385, CG=0.796113, CT=5.584748, GT=1.0; gamma distribution shape parameter α=0.132147 with a final likelihood value of − 3623.854076. Ex-type strains are in bold and newly generated sequences are in blue bold. Bootstrap support for ML equal to or greater than 50% and BI equal to or greater than 0.90 are given at the nodes

Figure 2 – (continued)