Skoliomycella flava Réblová & Hern.-Restr., 2025

Réblová, Martina, Nekvindová, Jana, Bauchová, Lucie & Hernández-Restrepo, Margarita, 2025, Pleurophragmium parvisporum (Ascomycota): One name, seven stories – a case highlighting the need for verification of strains from public culture collections, IMA Fungus 16, pp. e 173033-e 173033 : e173033-

Skoliomycella flava Réblová & Hern.-Restr. sp. nov.

Fig. 9

Etymology.

From Latin flavus (yellow). Referring to the yellow pigment released by the colonies into the surrounding agar.

Typus.

PORTUGAL • Minho province, Melgaço, Fonte de São João ; unidentified plant debris; Nov 2007; J. Capilla, R. F. Castañeda-Ruiz & C. Silvera ( holotype CBS H-25776 dried culture, ex-type culture CBS 122759 = FMR 9646 ) .

Culture characteristics.

On CMD colonies 9–10 mm diam., circular, raised, margin entire or slightly undulate, floccose to velvety becoming mucoid, zonate, olivaceous-brown, ochre at the margin surrounded by isabelline halo, with a prominent submerged growth, reverse beige-yellow. On MLA colonies 10–12 mm diam., circular, convex, margin undulate, velvety, zonate, whitish-purple to whitish-brown with an outer thin purple zone, ochre-cream at the margin, with a submerged growth, pale yellow pigment diffusing into the agar, reverse ochre. On OA colonies 9–10 mm diam., circular, flat, margin undulate, velvety, off-white to whitish-brown, brown towards the periphery, with pale ochre-brown halo, pale ochre pigment diffusing into the agar, reverse ochre-brown. On PCA colonies 8–10 mm diam., circular, convex, margin undulate, velvety, zonate, cream to beige-brown, with thin purple-brown and golden-ochre zones at the margin, pale yellow pigment diffusing into agar, reverse ochre. Sporulation absent on CMD, moderate on MLA, OA and PCA.

Description in culture.

Colonies on MLA effuse. Sexual morph. Not observed. Asexual morph. Mycelium composed of hyaline, subhyaline to pale brown, branched, septate hyphae, 1.5–2.5 µm wide, occasionally slightly swollen. Conidiophores (22 –) 35–102 × 3–5 µm, macronematous, mononematous, sometimes reduced to a single conidiogenous cell without or with 1–2 supporting cells, scattered or loosely aggregated, erect, cylindrical, some cells slightly inflated, unbranched, sometimes percurrently elongating, flexuous to sinuous, sometimes becoming geniculate exhibiting a zig-zag pattern due to local bending above the septum, each bend is associated with the formation of a single denticle on the ‘ outside’ giving the appearance of irregular or dichotomous branching, pale brown to golden brown, smooth-walled, septate. Conidiogenous cells 10–24 × 3–4 µm, integrated, terminal, form transverse septa during sympodial extension and become intercalary, occasionally lateral growing directly on hyphae, monoblastic or polyblastic with 1–4 peg-like denticles, cylindrical or subulate, subhyaline to pale olivaceous-brown when in the terminal position, golden-brown when intercalary, smooth-walled; conidiogenesis holoblastic-denticulate. Conidia 18.5–36 (– 45) × (3 –) 4–5.5 µm (mean ± SD = 27.1 ± 5.6 × 4.9 ± 0.1 μm), solitary, dry, acropleurogenous, oblong to cylindrical, elongate fusiform to narrowly ellipsoidal, tapering at both ends, truncate at the base 1–1.5 µm wide, with a conspicuous basal scar, usually straight, occasionally slightly curved, often with guttules or granules visible inside the cells, smooth-walled, aseptate and hyaline when young, at maturity with 3–7 transverse septa and subhyaline to pale olivaceous-brown, olivaceous-grey in mass; conidial secession schizolytic.

Habitat and geographical distribution.

Skoliomycella flava is a saprobe occurring on plant remnants. To date, two confirmed records originate from the Iberian Peninsula, specifically from Portugal (this study) and Spain (GlobalFungi), within a temperate, Mediterranean climate. According to GlobalFungi, it was detected in a single air sample from an anthropogenic biome, MAT ~ 14.5 ° C, MAP ~ 575 mm / year.

Notes.

Skoliomycella flava is readily distinguished from the morphologically similar species attributed to Camporesiomyces ( Hyde et al. 2020) and Zaanenomyces ( Crous et al. 2021) by the absence of a rachis in the fertile apical portion of the conidiogenous cell. Instead, its conidiophores are flexuous to sinuous, sometimes exhibit a zig-zag pattern, with a single denticle and / or a slightly prolonged conidiogenous cell formed at each bend on the outer side of the conidiophore, giving the impression of irregular or dichotomous branching.

The detection of S. flava in urban air highlights its capacity for aerial dispersal, although it occurs at very low relative abundance. However, its global distribution remains uncertain, as no additional records outside the Iberian Peninsula are available. Whether S. flava represents a rare, geographically restricted lineage, or whether its scarcity reflects limited sampling, or under-detection due to low environmental abundance, remains to be determined.

Figures

Figure 9. Skoliomycella flava (ex-type CBS 122759). A, B Sporulating conidiophores C – G conidiogenous cells with conidia H – K conidiophores with conidiogenous cells and conidia L – N conidia O diversity of colony morphology on CMD, MLA, OA, and PCA, respectively (from left to right) after 4 wk. Images: on MLA (A – N). Scale bars: 300 µm (A, B); 10 µm (C – N); 1 cm (O).