Penicillium irregulare Torres-Garcia, Gene and Dania Garcia, 2022

Torres-Garcia, Daniel, Gene, Josepa & Garcia, Dania, 2022, New and interesting species of Penicillium (Eurotiomycetes, Aspergillaceae) in freshwater sediments from Spain, MycoKeys 86, pp. 103-145 : 103

Penicillium irregulare Torres-Garcia, Gene and Dania Garcia sp. nov.

Figure 12

Etymology.

Referring to the variable branching pattern of the conidiophores of the species.

Type.

Spain, Comunidad de Madrid, Miraflores de la Sierra, Miraflores River , from sediments, Jun. 2019, J.F. Cano (holotype CBS H-24783, cultures ex-type CBS 148240 = FMR 17859 ) .

Subgeneric classification.

Subgenus Penicillium Penicillium , Penicillium section Canescentia , series Penicillium Canescentia .

Description.

Mycelium superficial and immersed, composed of septate, smooth-walled, hyaline hyphae, 2-3.5 μm wide. Conidiophores biverticillate, in minor proportion monoverticillate, terverticillate or divaricate; stipes smooth-walled, 13-152 × 1.5-2 μm; metulae divergent, 2-3 per stipe/branch, unequal in length, vesiculate, 7-10 × 1.5-2.5 μm (vesicle up to 4 μm wide), occasionally a solitary phialide borne on same level as metulae; phialides 5-8 per metula, ampulliform, 6-7.5 × 1.5-2.5 μm; conidia smooth- to finely rough-walled, globose to subglobose, somewhat ellipsoidal, 1.5-3 × 1.5-2 μm.

Culture characteristics (7 d at 25 °C).

Colonies on CYA, 36-38 mm diam, slightly elevated, radially sulcate, velvety, grayish orange (6B3) at center and white (1A1) towards periphery, margins entire, sporulation abundant, conidial masses grayish green (25B3); reverse brownish yellow (5C8) at center and vivid yellow towards periphery (3A8); exudate and soluble pigment absent. On MEA, 33-34 mm diam, elevated, floccose, light yellow (4A4) at center and white (1A1) towards periphery, margins fimbriate, sporulation abundant, conidial masses grayish green (25C3); reverse yellowish orange (4A7); exudate and soluble pigment absent. On YES, 43-44 mm diam, raised, concentrically sulcate and pale yellow (4A3) at center, radially sulcate and white (1A1) towards periphery, velvety, margins entire, sporulation absent to sparse, conidial masses grayish green (25D2); reverse brownish yellow (5C8) and white (1A1) at periphery; exudate and soluble pigment absent. On OA, 25-27 mm, slightly elevated at center, cottony and fasciculate, dull green (25E4) at center, gray (1D1) and white (1A1) towards periphery, margins entire, sporulation abundant, conidial masses dull green (30E3); reverse yellowish brown (5F4), golden brown (5D7) towards periphery; soluble pigment absent. On DG18, 14-15 mm, elevated, velvety, white (1A1) with grayish turquoise (24E4) areas, margins slightly fimbriate, sporulation abundant, conidial masses grayish turquoise (24B3-C5); reverse yellowish green (30B8) at center to pale green (30A3) and white (1A1) at periphery; soluble pigment absent. On CREA, 12-13 mm, flat, floccose, yellowish green (29B7), margins regular, sporulation sparse, conidial masses grayish green (27B3-C3); reverse dark gray (1F1); soluble pigment and acid production absent.

Colony diameter on CYA after 7d (mm).

5 °C no growth, 15 °C 19-20, 20 °C 25-27, 30 °C 31-33, 35 °C 11-12, 37 °C 5-10, 40 °C no growth.

Distribution.

Spain.

Notes.

Penicillium irregulare is related to P. arizonense , P. yarmokense and P. canescens , all belonging to series Canescentia (Fig. 4 ). Species of this series are characterized by the production of biverticillate conidiophores, that occasionally produce additional branching stages (divaricate), with smooth- or rough-walled stipes ( Houbraken et al. 2020; Visage et al. 2021). Penicillium irregulare can be differentiated from its closest relative P. arizonense by the production of shorter stipes (13-152 μm vs 50-400 μm) and metulae (7-10 μm vs. 8-16 μm), and colony reverse yellowish to orange, in contrast to brown shades, even red brown to violet brown on YES agar in P. arizonense ( Grijseels et al. 2016). In addition, P. irregulare was able to grow at 37°C on CYA, but restrictedly (5-10 mm diam. 7 d), while P. arizonense does not grow at this temperature.

Figures

Figure 4. Phylogenetic tree of Penicillium section Canescentia based on ML analysis obtained by RAxML inferred from the combined tub 2, cmdA, ITS, and rpb 2 loci. Branch lengths are proportional to phylogenetic distance. Bootstrap support values / Bayesian posterior probability scores above 70 % / 0.95 are indicated on the nodes. Bold branches indicate bs / pp values 100 / 1. The tree is rooted to P. sacculum CBS 231.61 and P. senticosum CBS 316.67. The name in red is the new species described in this study. T = Ex-type strain.

Figure 12. Morphological characters of Penicillium irregulare sp. nov. (ex-type FMR 17859). A colonies from left to right (top row) CYA, MEA, YES, and OA; (bottom row) CYA reverse, MEA reverse, DG 18, and CREA B-G conidiophores on MEA H conidia. Scale Bars: 10 μm (B-H).