Gymnoascoideus alboluteus Guerra-Mateo, Cano & Gené, 2025

Gymnoascoideus alboluteus Guerra-Mateo, Cano & Gené sp. nov.

Fig. 7 View Figure 7

Etymology.

Referring to the white colonies with yellowish shades produced in culture.

Type.

Spain • Catalonia, Mediterranean coast, Tarragona, Platja de la Arrabassada , 41°6'45"N, 1°16'51"E, from sediments at 27 m depth, March 2022, G. Quiroga-Jofre & D. Guerra-Mateo ( holotype CBS H- 25762 , ex-type FMR 19992 View Materials , CBS 154002 View Materials ) GoogleMaps .

Description.

Saprobic on marine sediments. Mycelium superficial and immersed, composed of hyaline, septate, branched, smooth-walled, 2.5–3 µm wide hyphae. Asexual morph with straight, branched, cylindrical, 2.5–3 µm wide fertile hyphae, giving rise to arthroconidia in a random disposition. Arthroconidia enteroarthric, 0–1 - septate, hyaline, smooth- and thin-walled, cylindrical to subcylindrical, barrel- or T-shaped, campaniform, with conspicuous frills, (2.5 –) 3.5–6 (– 9) × 2.5–3 µm; secession rhexolytic. Racket hyphae present. Sexual morph not observed.

Culture characteristics

(after 14 days at 25 ° C). Colonies on OA reaching 24–26 mm diam., flat with sparse aerial mycelium, white (1 A 1), margin entire and submerged; reverse uncolored. On PDA, 30 mm diam., crateriform, slightly elevated, radially sulcate, fasciculate in center to velvety towards periphery, white (1 A 1) with light yellow (3 A 4) exudate in center, margin entire; reverse uncolored. Diffusible pigment light yellow (3 A 4). On PYE, 36 mm diam., slightly elevated, radially sulcate, woolly or floccose, yellowish grey (4 B 3) to white (1 A 1), margin fimbriate; reverse radially sulcate, olive brown (4 D 8) to white (1 A 1).

Cardinal temperatures for growth.

Minimum 5 ° C ( 2 mm), optimum 25 ° C ( 30 mm), maximum 35 ° C ( 1 mm).

Habitat and geographic distribution.

Marine sediments in Spain. In GlobalFungi, in soil from forests and wetlands. Australia, China, and the Czech Republic (Fig. 4 View Figure 4 ).

Notes.

Gymnoascoideus alboluteus represents an independent lineage phylogenetically related to Gd. petalosporus and Gd. boliviensis (Fig. 3 View Figure 3 ). Macroscopically, these species differ in colony coloration on OA and PYE; Gd. petalosporus displays white colonies with buff or greenish-brown shades ( Orr et al. 1977), while in Gd. alboluteus they are white with yellowish areas, and Gd. boliviensis exhibits colonies in orange shades ( Guarro et al. 1992 b). Microscopically, the three species produce the asexual morph, which is characterized by fertile hyphae that give rise to arthroconidia randomly. The morphological differences between their asexual morphs are the following: Gd. petalosporus displays buff or brown arthroconidia of 2.1–11.9 × 1.4–5.6 µm ( Orr et al. 1977), Gd. alboluteus produces hyaline arthroconidia of 2.5–9 × 2.5–3 µm, and in Gd. boliviensis , they are also hyaline but slightly smaller (2–7 × 2–2.5 µm) ( Guarro et al. 1992 b). Another difference is the lack of racket hyphae in the latter species, which are present in Gd. petalosporus and Gd. alboluteus . In addition, Gd. petalosporus and Gd. boliviensis produce sexual morphs in culture. Although we have not observed the sexual morph for Gd. alboluteus in any of the media tested, the great phylogenetic distance to other species of the genus confirms it as a novel species.