Deilomyces minimus Guerra-Mateo, Gené & Cano, 2025

Deilomyces minimus Guerra-Mateo, Gené & Cano sp. nov.

Fig. 6 View Figure 6

Etymology.

Latin minimus , small, referring to the small size of reproductive structures.

Type.

Spain • Catalonia, Mediterranean coast, Estartit, discharging area of the Ter River , 42°1'34"N, 3°13'7"E, from sediments at 27 m depth, April 2023, D. Guerra-Mateo & J. Gené ( holotype CBS H- 25613 ; cultures ex-type FMR 20744 View Materials , CBS 152721 View Materials ) GoogleMaps .

Description.

Saprobic on marine sediments. Mycelium immersed and superficial, composed of hyaline, septate, branched, smooth-walled, 1.5–2 µm wide hyphae. Asexual morph Chrysosporium - like. Conidia thallic, terminal or intercalary, occasionally lateral on short stalks, hyaline to subhyaline, smooth-walled to tuberculate, thick-walled; terminal and lateral conidia on straight or slightly curved branches, aseptate, subglobose, obpyriform, or short clavate with truncated base, 3–4.5 × 2.5–3 µm; intercalary conidia alternate, frequently disposed in a knuckle joint position, 0 – (1) - septate, constricted at septum, subglobose, subcylindrical, obpyriform, or short clavate with truncated base, 5.5–8.5 (– 10.5) × 2.5–3 µm. Sexual morph with gymnothecial ascomata. Gymnothecia superficial, single or aggregated, initially white, turning pale yellow at maturity, globose or subglobose, 150–550 µm diam.; peridium composed of a subtle network of septate, branched, anastomosed, hyaline, smooth- and thick-walled, cylindrical, 1.5–2 µm wide hyphae; peridial appendages absent. Asci 8 - spored, evanescent, globose, subglobose, or pyriform, 4.5–6 × 4–5 µm. Ascospores unicellular, pale yellow, smooth- and thick-walled, globose, subglobose, ellipsoidal, or irregularly shaped, 2.5 × 1.5–2.5 µm.

Culture characteristics

(after 14 days at 25 ° C). Colonies on OA reaching 13–16 mm diam., flat, predominantly submerged, aerial mycelium sparse, with scattered white (1 A 1) ascomata towards periphery, margin diffuse; reverse uncolored; producing a conspicuous urea odor. On PDA, 5–7 mm diam., slightly umbonate, floccose and white (1 A 1) at center, velvety and yellowish white (4 A 2) towards periphery, margin diffuse; reverse uncolored. On PYE, 3–4 mm diam., umbonate, woolly, white (1 A 1), margin feathery; reverse uncolored. Diffusible pigment not observed in any of the media studied.

Cardinal temperatures for growth.

Minimum 20 ° C ( 3 mm), optimum 25 ° C ( 7 mm), and maximum 30 ° C ( 3 mm).

Habitat and geographic distribution.

Marine sediments in Spain. In GlobalFungi, in soil from different environments (forests, woodland, grassland, wetland, cropland, and urban), water, rhizosphere soil, plant shoots, roots, and freshwater sediments. Argentina, Australia, Brazil, China, Colombia, Cuba, Germany, Italy, Nigeria, Panama, South Africa, Tanzania, and the USA (Fig. 5 View Figure 5 ).

Notes.

Deilomyces minimus is phylogenetically related to Diploospora rosea (Fig. 2 View Figure 2 ). These two fungi represent two genera based on the great phylogenetic distance between them and the distinct pattern of conidiogenesis; while D. minimus shows a Chrysosporium - like asexual morph with thallic conidia, Di. rosea displays a mixture of blastic and thallic conidia arising in acropetal, sometimes basipetal, chains directly from the hyphae ( Tanney et al. 2015). The asexual morph of D. minimus resembles that of Amaurascopsis ( As.) perforata ( Guarro et al. 1992 a) , Polytolypa ( P.) hystricis ( Scott et al. 1993) , and Pseudoamaurascopsis ( Pd.) spiralis ( Torres-Garcia et al. 2023). These three species represent an incertae sedis lineage in Onygenales , defined as clade X by Torres-Garcia et al. (2023). These species are characterized by the production of Chrysosporium - like thallic, terminal, and intercalary, smooth-walled or tuberculate conidia. Deilomyces minimus can be distinguished from As. perforata by smaller terminal conidia (3–4.5 × 2.5–3 µm vs. (3) 4–6.5 (7.5) × 2.5–4.5 µm) ( Guarro et al. 1992 a), from Pd. spiralis by shorter intercalary conidia [5.5–8.5 (– 10.5) µm long vs. 7–15 (– 22.5) µm long] ( Torres-Garcia et al. 2023), and from P. hystricis by the conidial ornamentation (smooth to tuberculate vs. smooth) ( Scott et al. 1993). In addition, the sexual morph of D. minimus resembles those of the phylogenetically distant species of the family Neoarthropsidaceae , Albidomyces ( Al.) albicans and Neoarthropsis ( Ne.) sexualis . These species produce gymnothecial ascomata composed of a conspicuous network of hyaline to pale yellow and smooth hyphae, subglobose to pyriform, evanescent asci, and globose or subglobose ascospores. Deilomyces minimus can be distinguished from Ne. sexualis by smaller ascomata and thinner peridial hyphae (150–550 µm vs. 365–810 µm diam., and 1.5–2 µm vs. 3–4 µm wide, respectively), and differs from Al. albicans by smaller asci and ascospores (4.5–6 × 4–5 µm vs. 8–11 × 11–17 µm, and 2.5 × 1.5–2.5 µm vs. 3–5 × 3–4.5 µm, respectively). Moreover, the ascospores of D. minimus are smooth, while those of Ne. sexualis and Al. albicans are punctate and punctate to reticulate, respectively ( Torres-Garcia et al. 2023).