Juxtiphoma kolkmaniorum 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

Juxtiphoma kolkmaniorum Hern.-Restr., L. W. Hou, L. Cai & Crous sp. nov. Figure 5

Etymology.

kolkmaniorum refers to Linde & Mette Kolkman who collected the soil sample from which the ex-type strain was isolated.

Typus.

The Netherlands. Ophemert, isolated from garden soil, Mar. 2017, L. & M. Kolkman (holotype designated here CBS H-24214, living ex-type culture CBS 146005 = JW 185006).

Conidiomata pycnidial, superficial, solitary or confluent, globose to subglobose, brown to dark brown, glabrous, covered by dark hyphae and chlamydospores, 100-350 μm; uniostiolate papillate; pycnidial wall pseudoparenchymatous, 2-4 layers, 7.5-12.5 μm thick, outer layer composed of brown, flattened polygonal cells. Conidiogenous cells mono- or polyphialidic, hyaline, smooth, subcylindrical, ampulliform or somewhat isodiametric, 5.5-11.5 × 2.5-5.5 μm. Conidia ellipsoidal to oblong, straight or curved, thin- and smooth-walled, hyaline, aseptate, 3.5-7.5 × 2-3 μm, 1-3-guttulate, medium. Conidial matrix white to buff. Chlamydospores terminal or intercalary, solitary, or in simple or branched chains, barrel-shaped, subglobose or ellipsoidal, pale brown to brown, guttulate, 5.5-12 × 4-8 μm.

Culture characteristics.

Colonies after 7 d at 25 °C, on OA reaching 45-60 mm diam, aerial mycelium cottony to floccose, isabelline to olivaceous, margin irregular; reverse concolorous. On MEA reaching 45-55 mm diam, aerial mycelium cottony to floccose, smoke grey to pale olivaceous grey with white edge, margin entire; reverse buff to smoke grey near the centre, olivaceous black with buff edge. On PDA reaching 45-50 mm diam, aerial mycelium cottony to floccose, olivaceous buff, dull green to buff, margin irregular; reverse smoke grey near the centre, olivaceous black with buff edge. NaOH spot test negative on OA.

Additional specimens examined.

Germany. Kiel-Kitzeberg, from wheat field soil, 1966, W. Gams, living cultures CBS 527.66 = FMR 15337 = ATCC 22238; The Netherlands. North Brabant province, Breda, isolated from garden soil, Mar. 2017, F. Versantvoort, JW 167004; ibid. JW 168007; Rijen, isolated from garden soil, Mar. 2017, G. & L. Schijvenaars, JW 94009. North Holland province, Hilversum, isolated from garden soil, Mar. 2017, S. Nieuwenhuijsen, JW 23021. Utrecht province, Amersfoort, isolated from garden soil, Mar. 2017, M. Kerssen, JW 125028; Amersfoort, isolated from garden soil, Mar. 2017, E., K. & O. de Jong Verpaalen, JW 241011; Amersfoort, isolated from garden soil, Mar. 2017, F. Wiegerinck, specimen CBS H-24102, culture CBS 145911 = JW 4017; Amersfoort, isolated from garden soil, Mar. 2017, T. & K. Wesselink, JW 191004; Bilthoven, isolated from garden soil, Mar. 2017, Y. El Ghazi, JW 220011; Utrecht, isolated from garden soil, Mar. 2017, J. Kooijmans, JW 63001.

Notes.

Juxtiphoma kolkmaniorum is very similar and phylogenetically close to J. eupyrena . However, based on the multi-gene phylogenetic analyses, J. kolkmaniorum forms a separate clade (Figure 1 ). Morphologically, J. kolkmaniorum has conidia slightly larger and with more guttules than those of J. eupyrena (3.5-7.5 × 2-3 μm, 1-3-guttulate vs. 4.2-5.6 × 1.8-2.4 μm, 2-guttulate, de Gruyter and Noordeloos 1992) and smaller chlamydospores (5.5-12 × 4-8 μm vs. 8-20 × 6-15 μm, de Gruyter and Noordeloos 1992).

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 5. Juxtiphoma kolkmaniorum (CBS 146005). 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, H pycnidium forming on OA I chlamydospores J-L conidiogenous cells M conidia. Scale bars: 100 μm (G, H); 10 μm (I-M).