Dothiora coronicola Dissanayake, Camporesi & K.D. Hyde, sp. nov.
Index Fungorum number: IF 556815; MycoBank number: MB 556815; Facesoffungi number: FoF 06509; Fig. 1
Etymology – In reference to the host Coronilla, and cola meaning loving.
Holotype – MFLU 16-1110
Saprobic on dead aerial branch of Coronilla emerus L. Sexual morph Ascomata 215–430×240–285 µm, immersed or erumpent through the epidermis, solitary or clustered, globose, brown to black, with single locules. Peridium 39–76 µm wide, two-layered, outer layer composed of dark brown or brown, thick-walled cells of textura angularis, inner layer composed of hyaline, thin-walled cells of textura angularis. Asci 80–145×15–30 µm (x̅=120×24 µm, n=20), 8-spored, bitunicate, fissitunicate, cylindro-clavate, pedicellate, apically rounded, with a small ocular chamber. Ascospores 21–25×8–11 µm (x̅=23×10 µm, n=30), bi-seriate to multiseriate, hyaline, aseptate, fusoid to ovoid, one end narrower than the other, smooth-walled with granular contents, lacking a mucilaginous sheath. Asexual morph Undetermined.
Culture characteristics – Colonies on PDA reaching 2 cm after 14 days at 25 °C, mycelium velvety and moderately fluffy with an irregular margin, surface initially white and later turning dark yellow from the middle of the colony and dark grey in reverse.
Material examined – ITALY, Province of Forlì-Cesena, near Passo delle Forche- Galeata, on dead aerial branch of Coronilla emerus (Fabaceae), 30 March 2016, E. Camporesi, IT 2894 (MFLU 16-1110, holotype), ex-type living culture, MFLUCC 17-1007.
GenBank numbers – ITS=MZ571206, LSU=MZ571207.
Notes – We were able to obtain a culture from a single conidium. In the phylogenetic analysis, Dothiora coronicola forms a distinct lineage basal to D. buxi, D. cactacearum, D. coronillae and D. spartii with 96% MLBS support (Fig. 2). However, this taxon can be differentiated from above mentioned species as follows. Dothiora buxi has polysporous asci with 32 ascospores in an ascus, while D. coronicola has asci with only eight ascospores. Dothiora buxi also has pale brown ascospores, whereas D. coronicola has hyaline ascospores (Fig. 1). The placement of D. buxi within the Dothiora was proven by molecular data (Hyde et al. 2016). Morphological variations of D. coronicola and D. cactacearum cannot be compared as the latter composed only an asexual morph. Dothiora coronicola can be easily distinguished from D. coronillae as the latter comprised with cylindro-clavate asci (Hyde et al. 2017). Both D. coronicola and D. spartii are morphologically comparable but phylogenetically they cluster in two different places (Fig. 2).
Figure 1 – Dothiora coronicola (MFLU 16-1110, holotype). a, b Ascomata on host surface. c Section through the ascoma. d Peridium. e, f Asci. g Ascospore. h Culture on PDA. Scale bars: c, d=100 μm, e, f=50 μm, g=20 μm
Figure 2 – Phylogram generated from maximum likelihood analysis based on combined LSU and ITS sequence data representing Dothiora coronicola (MFLUCC 17-1007) and related species. The scale bar indicates 0.01 changes. The tree is rooted to Dothidea sambuci (AFTOL-ID 274). Related sequences were taken from Hongsanan et al. (2020a). Twenty-two sequences are included in the analysis which comprise 1396 characters after alignment. The best RAxML tree with a final likelihood value of − 3690.034105 is presented. The matrix had 195 distinct alignment patterns, with 5.69% undetermined characters or gaps. Estimated base frequencies are as follows: A=0.251756, C=0.223630, G=0.280088, T=0.244526; substitution rates AC=1.042605, AG=2.446647, AT=1.739048, CG=0.584297, CT=5.850014, GT=1.000000; gamma distribution shape parameter α=0.020014. Bootstrap values for maximum likelihood (MLBS) equal to or greater than 70% are indicated at the nodes. Type and extype strains are in bold and the newly generated sequence is in blue