Cladosporium pseudotenellum Iturrieta-Gonzalez , Dania Garcia , Gene, 2021

Iturrieta-Gonzalez, Isabel, Garcia, Dania & Gene, Josepa, 2021, Novel species of Cladosporium from environmental sources in Spain, MycoKeys 77, pp. 1-25 : 1

Cladosporium pseudotenellum Iturrieta-Gonzalez, Dania Garcia, Gene sp. nov. Fig. 7

Etymology.

The name refers to " C. tenellum ", the closest phylogenetic species.

Type.

Spain, Catalonia, Tarragona province, Reus, garden soil, Feb. 2017, I. Iturrieta-González (holotype CBS H-24473; cultures ex-type FMR 16231, CBS 146922).

Description.

Mycelium in vitro superficial and immersed, composed of septate, branched, subhyaline to pale brown, smooth-walled, occasionally tuberculate and with abundant swellings, hyphae, 2-3(-4.5) μm wide. Conidiophores macronematous, arising laterally or terminally from hyphae, erect to slightly flexuous, non-nodulose, occasionally geniculate at the apex, septate, unbranched, occasionally branched, up to 146 μm long, 2.5-3 μm wide, pale brown, smooth to slightly verruculose. Conidiogenous cells integrated, terminal or intercalary, cylindrical, sometimes geniculate, 15-32 × 2.5-3 μm, with up to five conidiogenous loci, thickened, darkened and refractive, often crowded at the apex. Ramoconidia rarely formed, 0(-1)-septate, ellipsoidal to subcylindrical, 9-14.5 × 4-5.5 μm [av. ( ± SD) 11.6 ( ± 1.60) × 4.6 ( ± 0.44)], pale brown, verruculose. Conidia forming branched chains, with up to four conidia in the terminal unbranched part, aseptate, pale brown, verruculose to verrucose; small terminal conidia subglobose to obovoid, 4-7 × 3-5 μm [av. ( ± SD) 5.8 ( ± 0.77) × 3.9 ( ± 0.60)]; intercalary conidia ellipsoidal to limoniform, 6-8.5 × 3-5 μm [av. ( ± SD) 7.4 ( ± 0.73) × 3.8 ( ± 0.50)]; secondary ramoconidia 0(-2)-septate, ellipsoidal to subcylindrical, 7-12.5 × 4-5 μm [av. ( ± SD) 9.6 ( ± 1.76) × 4.4 ( ± 0.33)] with 1-3 distal hila.

Culture characteristics

(14 d at 25 °C). Colonies on OA reaching 21-22 mm diam., olive (2F8/2F4), flat, velvety, aerial mycelium scarce, margin fimbriate; reverse dark green (30F8) to black. On PDA attaining 29-30 mm diam., olive gray (3E2/3F2), paler at the periphery, radially folded, velvety, aerial mycelium scarce, margin slightly lobate; reverse dark green (30F8) to black. On SNA reaching 21-22 mm diam., olive (2F8), flat, slightly powdery, aerial mycelium scarce, margin fimbriate; reverse dark green (30F8) to black.

Cardinal temperature for growth.

Optimum 20 °C, maximum 30 °C, minimum 5 °C.

Distribution.

Spain.

Notes.

Based on the phylogeny of the C. herbarum complex (Fig. 2 ), C. pseudotenellum is closely related with C. tenellum , a species originally described from hypersaline water in Israel, later found on Phyllactinia sp. ( Erysiphaceae ), and in indoor air samples collected in the USA ( Schubert et al. 2007; Bensch et al. 2012, 2018). Our species differs from C. tenellum in the absence of micronematous conidiophores and in having shorter macronematous conidiophores (up to 146 μm vs up to 200 μm), shorter conidiogenous cells (15-32 μm vs 6-40 μm), with few conidiogenous loci (up to five vs up to 10 or more in C. tenellum ), and shorter ramoconidia (9-14.5 vs up to 32 μm). In addition, terminal and intercalary conidia in C. pseudotenellum are aseptate, while those of C. tenellum are 0-1(-3)-septate ( Schubert et al. 2007; Bensch et al. 2012).

Figures

Figure 2. Maximum likelihood (ML) tree obtained from the combined analysis of ITS, tef 1 and act sequences of 58 strains from C. herbarum complex. The tree is rooted with Cercospora beticola CBS 116456. Numbers on the branches represent ML bootstrap support values (MLBS) ≥ 70 %, followed by Maximum Parsimony bootstrap support values (PBS) ≥ 70 % and Bayesian posterior probabilities (PP) ≥ 0.95, lower values are indicate as " - ". Bold branches indicate MLBS / PBS / PP of 100 / 100 / 1. Names of species newly described are indicated in bold. Branch lengths are proportional to distance. T Ex-type strain. ET ex-epitype strain. NT ex-neotype strain.

Figure 7. Cladosporium pseudotenellum (ex-type FMR 16231) a-c colonies on PDA, OA and SNA after 14 days at 25 ° C d-e conidiophores f conidia. Scale bars: 10 mm (a-c); 10 μm (d-f).