Cladosporium lentulum 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 lentulum Iturrieta-Gonzalez, Dania Garcia, Gene sp. nov. Fig. 6

Etymology.

Name refers to its slower growth with respect to the phylogenetically related species (lentus = figuratively slow, with Latin adjectival suffix -ulus = diminutive).

Type.

Spain, Catalonia, Tarragona province, Tarragona, unidentified leaf litter, Feb. 2017, I. Iturrieta-González (holotype CBS H-24472; cultures ex-type FMR 16288, CBS 146921).

Description.

Mycelium in vitro superficial and immersed, composed of septate, branched, subhyaline to yellowish brown, smooth to verruculose hyphae, 1-4 μm wide. Conidiophores macronematous, arising laterally and terminally from hyphae, septate, erect to slightly flexuous, unbranched, sometimes geniculate at the apex, occasionally branched, up to 406 μm long, 3-4 μm wide, pale brown to brown, smooth to verrucose. Conidiogenous cells integrated, terminal and subterminal, cylindrical to subcylindrical, 11-27 × 2-4(-5) μm, bearing up to 5 conidiogenous loci, darkened and refractive. Ramoconidia 0(-2)-septate, subcylindrical to cylindrical, 10.5-23 × 2.5-4.5 μm [av. ( ± SD) 14.2 ( ± 2.61) × 3.2 ( ± 0.52)]; pale brown, smooth to verruculose. Conidia forming branched chains with up to 5 conidia in the unbranched part of the chain, pale brown, smooth to slightly verruculose, with protuberant, slightly darkened and refractive hila; small terminal conidia aseptate obovoidal to ellipsoidal, 4.5-7.5 × 1.5-2.5 μm [av. ( ± SD) 5.8 ( ± 0.81)) × 2.7 ( ± 0.29)]; intercalary conidia 0(-1)-septate, ellipsoidal to subcylindrical, 6-10.5 × 2-3 μm [av. ( ± SD) 8.4 ( ± 1.31) × 2.3 ( ± 0.34)]; secondary ramoconidia 0(-1)-septate, ellipsoidal to subcylindrical, slightly constricted at septum when present, 7.5-14.5 × 2-3 μm [av. ( ± SD) 10.5 ( ± 2.05) × 2.5 ( ± 0.30)].

Culture characteristics

(14 d at 25 °C). Colonies on OA reaching 19-20 mm diam., olive (3F8), flat, velvety, aerial mycelium scarce, margin regular; reverse dark green (30F8) to black. On PDA attaining 28-36 mm diam., dark green (27F8), with a whitish final edge, slightly umbonate, radially folded, velvety, aerial mycelium scarce, margin slightly lobulate; reverse olive brown (4E4), whitish at the edge. On SNA reaching 22-23 mm diam., olive (3F5), flat, slightly dusty, 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.

Additional specimen examined.

Spain, Catalonia, Tarragona province, Poblet, unidentified herbivore dung, Mar. 2017, I. Iturrieta-González, M. Guevara-Suarez & J. Guarro (FMR 16389).

Notes.

Our phylogeny shows C. lentulum included in a well-supported terminal clade together with the ex-type strains of C. exasperatum , C. parapenidielloides and C. longicatenatum , three species all described from plant material collected in Australia ( Bensch et al. 2010, 2015). However, the genetic distance allows it to be considered a distinct species within the clade (Fig. 1 ). Phenotypically, C. lentulum can be distinguished from its counterparts mainly by its slower growth, especially on OA at 25 °C after 14 d (19-20 mm vs 39-54 mm for C. exasperatum , 42-55 mm for C. parapenidielloides and 43-54 mm for C. longicatenatum ). In addition, our new species shows shorter ramoconidia (10.5-23 μm) than C. exasperatum and C. longicatenatum (19-40 μm and 22-42 μm, respectively); ramoconidia in C. parapenidielloides are absent; the conidia in C. lentulum are smooth or nearly so, while those of C. exasperatum and C. longicatenatum possess a unique verruculose-rugose conidial surface ornamentation, especially prominent in the former; and conidiophores in C. parapenidielloides are much shorter (up to 67 μm) than those observed in C. lentulum (up to 406 μm) ( Bensch et al. 2010, 2015).

Figures

Figure 1. Maximum likelihood (ML) tree obtained from the combined analysis of ITS, tef 1 and act sequences of 101 strains from the C. cladosporioides complex. The tree is rooted with C. sphaerospermum CBS 193.54 and C. longissimum CBS 300.96. 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.

Figure 6. Cladosporium lentulum (ex-type FMR 16288) a-c colonies on PDA, OA and SNA after 14 days at 25 ° C d-e conidiophores f-g conidia. Scale bars: 10 mm (a-c); 10 μm (d-g).