Curvularia suttoniae Iturrieta-Gonzalez , Wiederhold, Gene & Dania Garcia, 2020

Iturrieta-Gonzalez, Isabel, Gene, Josepa, Wiederhold, Nathan & Garcia, Dania, 2020, Three new Curvularia species from clinical and environmental sources, MycoKeys 68, pp. 1-21 : 1

Curvularia suttoniae Iturrieta-Gonzalez, Wiederhold, Gene & Dania Garcia sp. nov. Fig. 3

Etymology.

Named in honour of the American mycologist Deanna A. Sutton for her contribution to the body knowledge of microfungi.

Type.

USA, Texas, from a human leg wound, 2009, D.A. Sutton (holotype CBS H-24294, culture ex-type UTHSC 09-3575, CBS 146221, FMR 10992).

Description

(PDA at 25 °C). Mycelium consisting of branched, septate, pale brown, smooth-walled to verruculose hyphae, 1-4 µm wide. Conidiophores mononematous, semi- to macronematous, erect to slightly flexuous, geniculate at the apex, unbranched or branched, smooth-walled to verruculose, pale brown, 43-103 × 3-5 µm (av. ( ± SD) 80 ( ± 32.35) × 3.7 ( ± 0.67)). Conidiogenous cells terminal, subterminal or intercalary, polytretic, proliferating sympodially, pale brown, darkened scars, subcylindrical to slightly swollen, 3-5 µm wide. Conidia (2-)3-septate, straight or curved, with the third cell often larger than the rest, apical and middle cells smooth-walled, basal cell verruculose, pale brown to brown, apical and basal cells paler than the middle cells, 8-22 × 5-9 µm (av. ( ± SD) 15 ( ± 9.89) × 6.88 ( ± 1.18)); hila protuberant, thickened and darkened. Sexual morph not observed.

Culture characteristics

(7 d at 25 °C). Colonies on PDA reaching 66-68 mm diam., yellowish-grey (4B2), velvety, flat, margin slightly irregular and fimbriate; reverse black to brownish-orange (5C4); soluble pigment brown (6E6) present in cultures between 30-37 °C. On PCA, reaching 67 mm diam., olive grey (3D2), slightly floccose at the centre, flat, margin regular and whitish; reverse olive grey (3D2), whitish towards periphery. On OA, reaching 64 mm diam., olive grey (3F2), slightly floccose at the centre, flat, margin regular and whitish; reverse olive grey (3F2). Scarce sporulation on the three media.

Cardinal temperature for growth.

Optimum 25-30 °C, maximum 37 °C, minimum 5 °C.

Distribution.

USA.

Additional specimen examined.

USA, South Carolina, from human sphenoid sinus, 2008, D.A. Sutton (UTHSC 08-809, FMR 11690).

Notes.

Curvularia suttoniae is included in a well-supported clade with C. petersonii and C. vietnamensis , the latter also described here. Although the three species are clearly differentiated phylogenetically (Fig. 1 ), they can be distinguished only by subtle morphological features. While the conidia of C. petersonii and C. vietnamensis are entirely smooth, those of C. suttoniae show verruculose basal cells. Furthermore, the conidia in C. petersonii are narrower (5-7 µm wide) ( Tan et al. 2018) and, in C. vietnamensis , they are larger (15-28 × 5-12 μm) than those of C. suttoniae (8-22 × 5-9 µm). In addition to these morphological features, gapdh sequences easily distinguish the two latter species.

Figures

Figure 1. Phylogenetic tree of the Curvularia species most related to the new taxa based on Maximum Likelihood analysis obtained by RAxML, using the combined analysis of ITS, gapdh and tef 1 and rooted with Bipolaris maydis CBS 136.29 and Bipolaris saccharicola CBS 155.26. Bootstrap values (bs) greater than 70 % and Bayesian posterior probabilities (pp) greater than 0.95 are given at the nodes (bs / pp). Bold branches indicate bs / pp of 100 / 1. The novel species are highlighted in bold. Ex-type isolates are marked with a superscript T.

Figure 3. Curvularia suttoniae sp. nov. (ex-type FMR 10992). A-C Colonies on PDA, PCA and OA, respectively, at 25 ° C after 7 d D-I conidiophores and conidia with verruculose basal cells (arrows). Scale bars: 10 μm.