Wongia pallidopolaris 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-

Wongia pallidopolaris Réblová & Hern.-Restr. sp. nov.

Fig. 11

Etymology.

From Latin pallidus (pale), and polaris (of or relating to the poles). Referring to the conidial pigmentation, in which the apical and basal cells are distinctly paler than the central, more pigmented cells, creating a noticeable bipolar contrast.

Typus.

THE NETHERLANDS • Gelderland Province, Wageningen ; isolated from sandy soil under continuous wheat; Jan 1970; J. H. van Emden No. 4118, 30 ( holotype CBS H-25781 dried culture, ex-type culture CBS 440.70 ) .

Culture characteristics.

On CMD colonies 40–41 mm diam., circular, flat, margin entire to slightly fimbriate, diffuse, lanose, with a subtle concentric zoning, beige to grey-beige at the centre, brown at the margin, reverse dark brown. On MLA colonies 38–40 mm diam., circular, raised, margin entire, lanose, composed of camel brown and pale olivaceous brown concentric zones, reverse dark brown. On OA colonies 49–51 mm diam., circular, raised, margin entire, lanose, composed of beige, camel brown, dark brown and cinnamon concentric zones, brown at the margin, aerial hyphae at the centre and margin bearing numerous colourless exudates, reverse brown. On PCA colonies 44–45 mm diam., circular, convex, margin entire, lanose, whitish-grey at the centre surrounded with a thin smoke-grey zone, pale beige to light fawn towards the margin, reverse dark brown. Sporulation abundant on CMD, MLA, and PCA, absent on OA.

Description in culture.

Colonies on MLA effuse. Sexual morph. Not observed. Asexual morph. Mycelium composed of pale brown, septate, sparsely branched hyphae, 1.5–3 µm wide. Conidiophores 24–70 × 3.5–5 (– 5.5) µm, macronematous, mononematous, solitary or aggregated, erect, straight to slightly flexuous, apically almost sinuous, cylindrical, unbranched, occasionally proliferating sympodially, brown, dark brown in the lower part, smooth-walled, septate. Conidiogenous cells 12–30 × (4.5 –) 5–6 µm, integrated, terminal, mono- or polyblastic, with one to several denticles, extending sympodially, cylindrical, tapering, sometimes slightly swollen at the apex, pale brown, paler at the apex, smooth-walled; conidiogenesis holoblastic-denticulate. Conidia (20 –) 22–28 (– 30) × 5.5–6.5 (– 5.5) µm (mean ± SD = 25.2 ± 1.7 × 6.1 ± 0.3 μm), solitary, dry, acropleurogenous, ellipsoid to fusiform to fusiform-clavate, tapering towards both ends, truncate at the base 2–2.5 µm wide, with a conspicuous basal scar, mostly straight, occasionally slightly curved, brown to dark brown, end cells paler then the middle ones, apical cell often with a dark brown tip, smooth-walled to finely roughened, thick-walled, the outer wall partly detaches from the conidium, the detached segments appear as apical or side pocket or wings, sometimes the outer wall is detached around the base imitating a minute frill, 3 - septate, mucoid sheath absent; conidial secession schizolytic.

Habitat and geographical distribution.

The examined strain was isolated from sandy agricultural soil in the Netherlands. According to the GlobalFungi database, W. pallidopolaris was detected in 812 environmental samples. It is cosmopolitan, widely distributed in temperate to subtropical regions, with most records from North America, Europe, and Asia. The main hotspots are in the USA ( Michigan, New York and North Carolina), China (Provinces Fujian, Guizhou, Hebei, Jiangxi, Jilin and Yunnan), and central Europe (particularly Switzerland and the Netherlands), while additional, less frequent records originate from Australia and Africa. The species is primarily soil-associated (86.2 %), with occasional detection in roots, shoots and rare occurrence in air or water. It is predominantly associated with cropland (59.1 %) and grassland (28 %) ecosystems, followed by occasional occurrence in the anthropogenic habitats (6.4 %), forest (4.2 %) and woodland, aquatic, shrubland and wetland biomes. In both USA and China, W. pallidopolaris is strongly associated with cropland ecosystems, particularly cereals and legumes ( Zea mays , Glycine max , Oryza sativa , Chenopodium quinoa ). However, in China the species exhibits a broader ecological amplitude, occurring not only in croplands but also in forest soils, rhizospheres, and even aerosols, whereas in the USA it appears to be more restricted to cropland and anthropogenic soils. Occurrences are associated with MAT ~ 11.8 ° C and MAP ~ 926 mm / year.

Notes.

Wongia pallidopolaris closely resembles W. aquatica ( Luo et al. 2019) in having 3 - septate, brown conidia with paler end cells. However, W. aquatica differs in possessing shorter conidia, measuring 17–21 × 5–7 µm. Phylogenetically, both species form a strongly supported sister relationship within a monophyletic clade that is basal to all remaining Wongia species (Fig. 3 ).

Most conidia lacked any sheath-like structure; however, in a few cases, a similar feature was observed (Fig. 11 O ). It appeared on one or both sides near the base or apex, only at the apex, or occasionally at several points on the same conidium. This structure is slightly pigmented and resembles an outer wall layer that detaches in one or several places rather than a mucoid sheath. In other Wongia species, a mucoid sheath has not been reported. It is possible that in culture, where osmotic conditions differ from those in nature, the outer conidial wall deteriorates and partially detaches. In contrast, a similar structure observed in P. parvisporum represents a true mucoid but ephemeral sheath that is practically invisible on conidia from natural material yet clearly visible in culture, positioned laterally around the middle of the conidium (Fig. 7 N – P ) or covering the upper two-thirds (Fig. 7 D, E ).

Based on eDNA data, W. pallidopolaris is regarded as a cosmopolitan soil saprobe with strong ecological associations to cropland and grassland ecosystems. Its prevalence in agricultural soils suggests that human activity, particularly through agricultural practices, may have facilitated its dissemination. Its occasional detection in forest soils, rhizospheres, and even aerosols indicates that it can exploit a broader range of habitats. Despite its widespread occurrence in environmental samples, W. pallidopolaris represents a morphologically cryptic fungal lineage that has likely been overlooked in traditional surveys.

Figures

Figure 3. Maximum likelihood phylogenetic tree of the Papulosaceae based on ITS – LSU – SSU – rpb 2 – tef 1 DNA sequences. Names in bold indicate taxonomic novelties; strains with their accession numbers in bold and highlighted in violet colour were sequenced in this study. T and I denote ex-type and ex-isotype strains, respectively. Thickened branches indicate support ML BS = 100 % and PP values = 1.0. Branch support of nodes ≥ 70 % ML and ≥ 0.95 PP is indicated above or below branches. A hyphen (–) indicates values lower than 75 % ML BS or 0.95 PP.

Figure 7. Pleurophragmium parvisporum. A Sporulating conidiophores B – E upper part of conidiophores with terminal and intercalary conidiogenous cells (nodulose swellings) and conidia (arrows indicate mucoid sheath covering the upper two-thirds of the conidium) F – K conidiophores with conidiogenous cells and conidia L – P conidia (in N, O arrows indicate mucoid wing-like sheath; in P arrow indicates mucoid sheath that disintegrates in the upper part and detaches from the wall Q conidium with longitudinally crumpled wall (arrow indicates the original collapsed sheath which causes the ornamentation) R basal cells of conidiophores S diversity of colony morphology on CMD, MLA, OA, and PCA, respectively (from left to right) after 4 wk. Images: CBS 770.83 on OA (A – E, G – K, M – Q); CBS H- 3522 on natural substrate (F, L). Scale bars: 300 µm (A); 20 µm (G, R); 10 µm (B – F, H – Q); 1 cm (S).

Figure 11. Wongia pallidopolaris (ex-type CBS 440.70). A Sporulating conidiophores B – K conidiophores, conidiogenous cells and conidia L – O conidia P diversity of colony morphology on CMD, MLA, OA, and PCA, respectively (from left to right) after 4 wk. Images: on MLA (A – O). Scale bars: 300 µm (A); 10 µm (B – O); 1 cm (P).