Ascochyta benningiorum Hern.-Restr., L. W. Hou, L. Cai & Crous, 2020

Hou, Lingwei, Hernandez-Restrepo, Margarita, Groenewald, Johannes Zacharias, Cai, Lei & Crous, Pedro W., 2020, Citizen science project reveals high diversity in Didymellaceae (Pleosporales, Dothideomycetes), MycoKeys 65, pp. 49-99 : 49

Ascochyta benningiorum Hern.-Restr., L. W. Hou, L. Cai & Crous sp. nov. Figure 2

Etymology.

benningiorum refers to Eva, Bas & Anne Benning who collected the soil sample from which the ex-type strain was isolated.

Typus.

The Netherlands. Gelderland province, Wijchen, isolated from garden soil, Mar. 2017, E. Benning, B. Benning & A. Benning (holotype designated here CBS H-24104, living ex-type culture CBS 144957 = JW 196005).

Conidiomata pycnidial, mostly solitary, sometimes confluent, globose or subglobose, irregularly-shaped with age, brown to dark brown, glabrous, mostly produced on the agar surface and some immersed, 140-480(-580) × 100-370(-440) μm; with 1-6(-10) slightly papillate ostioles; pycnidial wall pseudoparenchymatous, 4-8 layers, 14.5-65 μm thick, outer layers composed of brown, flattened polygonal cells of 11-28 μm diam. Conidiogenous cells phialidic, hyaline, smooth, globose, ampulliform to lageniform, 5.5-9 × 4-6.5 μm. Conidia cylindrical, hyaline, smooth- and thin-walled, mostly straight, occasionally curved, aseptate, (3.5-)4.5-7 × 1.5-2.5 μm, 2-guttulate, small. Conidia matrix whitish.

Culture characteristics.

Colonies after 7 d at 25 °C, on OA reaching 50-55 mm diam, aerial mycelium floccose, olivaceous to olivaceous black, buff towards the periphery, abundant production of pycnidia, margin irregular; reverse concolorous with the surface. On MEA reaching 40-45 mm diam, aerial mycelium floccose, concentric circles, centre pink, grey olivaceous, mouse grey, rosy buff toward periphery, moderate production of pycnidia, margin irregular; reverse orange, olivaceous black toward periphery. On PDA reaching 45-50 mm diam, aerial mycelium floccose, dark brick to olivaceous grey, buff towards periphery, abundant production of pycnidia, margin irregular; reverse concolorous with the surface. NaOH spot test negative on OA.

Additional specimens examined.

The Netherlands. Gelderland province, Wijchen, isolated from garden soil, Mar. 2017, E. Benning, B. Benning & A. Benning, JW 196023 = CBS 144958; ibid. JW 196013.

Notes.

Ascochyta benningiorum is represented in the phylogenetic tree by three isolates (CBS 144957, CBS 144958 and JW 196013) from the same soil sample collected in Wijchen (Gelderland province). Ascochyta benningiorum grouped in a distinct clade close to A. phacae (Figure 1 ). However, it morphologically differs from A. phacae by having smaller (3.5-7 × 1.5-2.5 μm) and aseptate conidia. In A. phacae the conidia are 7-10 × 2-4 μm and 0-1-septate ( Corbaz 1955).

Species in Ascochyta are commonly regarded as plant pathogens, especially of cereal crops and legumes ( Davidson and Kimber 2007; Tivoli and Banniza 2007), and only a few species were reported from soil, namely A. fabae , A. lentis , A. pisi , A. rabiei ( Gossen and Morrall 1986; Tivoli and Banniza 2007) and A. syringae in the current study. Nevertheless, A. benningiorum is phylogenetically and morphologically distinct from these species (Figure 1 ; Chen et al. 2015).

Figures

Figure 1. Phylogenetic tree generated from the maximum-likelihood analysis based on the combined ITS, LSU, tub 2 and rpb 2 sequence alignment of Didymellaceae members. The RAxML bootstrap support values (BS), Bayesian posterior probabilities (PP), and parsimony bootstrap support values (PBS) are given at the nodes (BS / PP / PBS). BS and PBS values represent parsimony bootstrap support values> 50 %. Full supported branches are indicated in bold. The scale bar represents the expected number of changes per site. Ex-type strains are represented in bold. Strains obtained in the current study are printed in green; among them, whilst strains that represent new taxa are printed in red. Some of the basal branches were shortened to facilitate layout (the fraction in round parentheses refers to the presented length compared to the actual length of the branch). The tree was rooted to Coniothyrium palmarum CBS 400.71 and Leptosphaeria doliolum CBS 505.75.

Figure 2. Ascochyta benningiorum (CBS 144957). A, B Colony on OA (front and reverse) C, D colony on MEA (front and reverse) E, F colony on PDA (front and reverse) G pycnidia forming on OA H pycnidium I section of pycnidium J section of pycnidial wall K-M conidiogenous cells N conidia. Scale bars: 100 μm (H, I); 10 μm (J); 5 μm (K-N).