Diaporthe longipapillata Senan., sp. nov.
Index Fungorum number: IF 900444; MycoBank number: MB 900444; Facesoffungi number: FoF 14197; Fig. 1
Etymology: based on the long papilla of the ascomata.
Saprobic on dead twigs of unidentified plant. Sexual morph: Ascomata 620–946 × 350–500 µm (x = 370 × 490 µm, n = 10), perithecial, immersed to erumpent, scattered, solitary, globose, black, coriaceous, ostiolate with long, distinct papilla come out from the substrate. Paraphyses hyaline, cellular, dissolve when mature. Asci 80–90×16–19 µm (x=87×17.5 µm, n=30), 8-spored, unitunicate, elongate to clavate, sessile. Ascospores 19–23×5–7 µm (x=22×6.3 µm, n=50), overlapping biseriate, elongated to elliptical, two-celled, hyaline, often 4-guttulate with larger guttules at center and smaller ones at ends, dissolve when over mature. Asexual morph: Undetermined.
Culture characteristics – Colonies on PDA reaching 2 cm diam. after 10 days in dark at 25 °C, floccose, flat, circular, smooth margin, white, thick mycelial spreading over the colony; reverse off-white, no pigments produced.
Material examined – China, Guangdong Province, Guangzhou City, Haizhu District, Xiaogang park, on twigs of unidentified plant, 5 April 2021, I.C. Senanayake, 96 (MHZU 22-0108, holotype), ex-type cultures ZHKUCC 22-0180, ZHKUCC 22-0190.
GenBank numbers – ITS: OR164928, OR164929, tef1-α: OR166277, OR166278, cal: OR166301, OR166302, β-tubulin: OR166313, OR166314.
Notes – The combined gene analysis of ITS, β-tubulin, tef1-α and cal (Fig. 2) showed that our isolates (ZHKUCC 22-0180, ZHKUCC 22-0190) grouped with Diaporthe acutispora (CGMCC 3.18285) with ML/BI=100%/1.00 support. The base pair differences of ITS, β-tubulin, tef1-α and cal genes between our isolates and Diaporthe acutispora revealed that 3.72%, 4.76%, 13.96%, and 6.32% respectively. Phylogenetic network from the concatenated dataset based on the LogDet transformation and the NeighborNet algorithm, inferred by SplitsTree shows that our isolates do not show any recombination with the species members in Diaporthe arecae species complex and other well-delimitated species (Fig. 3a). However, we only obtain the sexual morph of our collection while D. acutispora was described from its asexual morph. Therefore, it is impossible to compare the morphology of our collection with D. acutispora. Diaporthe acutispora was collected from Yunnan Province, China on healthy leaves of Coffea sp. and Camellia sasanqua (Gao et al. 2017). Therefore, we introduce our collection as a new species of Diaporthe, D. longipapillata.
Figure 1 – Diaporthe longipapillata (MHZU 22-0108, holotype). a Examined material. b Ascomata on substrate. c Cross section of ascomata. d Peridium. e–h Asci. i–l Ascospores. m Surface view of colony on PDA. n Reverse view of colony on PDA. Scale bars: c=200 µm, d=50 µm, e–l=20 µm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined ITS, β-tubulin, tef1-α and cal sequence data which comprised 1801 characters (ITS=590, β-tubulin=399,tef1-α=401, cal=411). The best scoring RAxML tree with a final likelihood value of − 66,138.215080 is presented. The matrix had 1373 distinct alignment patterns, with 21.86% of undetermined characters or gaps. Estimated base frequencies were as follows: A=0.220620, C=0.327829, G=0.221919, T=0.229632; substitution rates: AC=1.155068, AG=3.569724, AT=1.178946, CG=0.924185, CT=4.411577, GT=1.0; gamma distribution shape parameter α=0.524319. Bootstrap support for maximum likelihood (ML) equal to or greater than 50% and clade credibility values greater than 0.90 (the rounding of values to 2 decimal proportions) from Bayesian inference analysis are labelled at each node. Ex-type strains are in bold, while the new isolate is indicated in blue bold. Except D. arecae species complex, other all species complexes are compressed. The tree is rooted to Cytospora disciformis (CBS 116827) and C. leucostoma (SXYLt)
Figure 3 – Phylogenetic network from the concatenated data (ITS, β-tubulin, tef1-α, cal) representing the structure of the a Diaporthe arecae, c D. eres species complexes and other well-delimitated species b the newly generated Diaporthe strains, based on the LogDet transformation and the NeighborNet algorithm, inferred by SplitsTree. The scale bar represents the expected number of substitutions per nucleotide position