Diaporthe campylandrae Senan., sp. nov.
Index Fungorum number: IF 900440; MycoBank number: MB 900440; Facesoffungi number: FoF 14192; Fig. 1
Etymology – based on the host plant Campylandra.
Saprobic on dead leaves of Campylandra chinensis (Baker) M. N. Tamura et al. Sexual morph: Undetermined. Asexual morph: Conidiomata 100–115 × 100–110 µm (x=109×102 µm, n=10), immersed, scattered on substrate, solitary, globose, dark brown to black, coriaceous, ostiolate, apapillate or indistinct papillate. Conidiophores reduce to conidiogenous cells. Conidiogenous cells 9–11×1–2 µm (x=9.8×1.8 µm, n=20), annellidic, without visible periclinal thickening, collarets very flared, cylindrical to ampulliform, slightly tapered towards the apex, frills-like structure remain at apex, straight or sinuous, aseptate, densely aggregated, terminal, hyaline, thick-walled. Alpha conidia 2–3×1.5–2 µm (x=2.5×1.7 µm, n=20), fusiform or oval, both ends obtuse or acute, aguttulate to small, biguttulate, hyaline, unicellular. Beta conidia not observed.
Culture characteristics – Colonies on PDA reaching 3 cm diam. after 10 days in dark at 25 °C, floccose, flat, circular, entire margin, white, wooly aerial mycelia concentrate at the center, reverse off-white, no pigments produced.
Material examined – China, Guangdong Province, Guangzhou City, Baiyun Mountain (23° 09′ 35″ N 113° 17′ 40″ E), on dead leaves of Campylandra chinensis (Convallariaceae), 16 August 2021, I.C. Senanayake, 11-2 (MHZU 22-0111, holotype), ex-type cultures ZHKUCC 22-0183, ZHKUCC 22-0193.
GenBank numbers – ITS: OR164922, OR164923, tef1-α: OR166271, OR166272, cal: OR166297, OR166298, β-tubulin: OR166307, OR166308.
Notes – Our isolates (ZHKUCC 22-0183, ZHKUCC 22-0193) clustered with Diaporthe sennicola (CFCC 51634) in the combined ITS, β-tubulin, tef1-α and cal gene analysis (Fig. 2) with ML/BI=100%/1.00 bootstrap support. The base pair differences of ITS, β-tubulin, tef1-α and cal between our isolates and Diaporthe sennicola revealed 2.37%, 1%, 4.23%, 1.94% 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 have any recombination with D. sennicola and related well delimitated species (Fig. 3b). Morphologically, our collection differs from Diaporthe sennicola by globose conidiomata immersed in substrate, absence of ectostromatic disc and conidiophores with fusiform to oval aguttulate conidia while D. sennicola has compressed globose conidiomata, dark brown, flat ectostromatic disc, phialidic, branched conidiophores and ellipsoidal, conspicuously biguttulate conidia (Yang et al. 2017a). Further, colonies of D. sennicola are initially flat with white felty aerial mycelia and turn to white compact furcate mycelia at the centre and auburn furcate mycelia at the irregular margin while our isolates have circular, white colonies with entire margin. Therefore, we introduce our collection as a new Diaporthe species, D. campylandrae.
Figure 1 – Diaporthe campylandrae (MHZU 22-0111, holotype). a Examined material. b Cross section of conidioma. c–f Conidia attached to conidiogenous cells. g Conidia. h Surface view of colony on PDA. i Reverse view of colony on PDA. Scale bars: b=70 µm, c–f=10 µm, g=2.5 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