Halomyrma pluriseptata Réblová & Vohník, 2025

Halomyrma pluriseptata Réblová & Vohník sp. nov.

Figs 5 View Figure 5

Etymology.

From Latin pluri (many or multiple) and septatus (partitioned or divided by septa). Referring to the characteristic multiseptate conidia.

Type.

CZECHIA • Karlovy Vary Region, Cheb district, Soos National Nature Reserve near Františkovy Lázně ; slightly saline soil (pH 7.2); 2005; leg. & isol. M. Hujslová M. H. 779 (holotype PRA -22368 dried culture on CMD, ex-type culture CCF 3788 View Materials = CBS 153583 View Materials , paratype PRA -22369 dried culture on MLA). GenBank: ITS = PV 441105 , LSU = PV 441119 , SSU = PV 441112 (this study); SSU, ITS, LSU = FJ 430723 View Materials ( Hujslová et al. 2010) .

Culture characteristics.

On CMD colonies 50–55 mm diam. in 2 wk, circular, slightly raised, margin flat and entire, whitish centrally, grey towards the margin due to formation of immersed conidia, floccose at the inoculation block, cobwebby towards the periphery, reverse dark olivaceous grey. On MLA colonies 35–36 mm diam. in 2 wk, convex, margin flat and entire, irregularly whitish-grey and floccose at the centre, grey and cobwebby towards the periphery, olivaceous grey at the margin, reverse olivaceous grey. On OA colonies 39–43 mm diam. in 2 wk, circular, flat, margin entire, floccose and partially funiculose at the inoculation block, cobwebby to mucoid towards the periphery, white at the centre, irregularly brown towards the margin, a deep golden-yellow pigment diffusing into the agar, reverse golden-yellow with dark olivaceous brown spots. On PCA colonies 33–40 mm diam. in 2 wk, convex, margin flat and entire, floccose, white at the centre, irregularly dark grey towards the periphery due to abundant immersed conidia, a pale yellow pigment diffusing into the agar, reverse yellow or dark olivaceous brown. On PCASW colonies 28–30 mm diam. in 2 wk, circular, flat, margin entire, lanose, sparse towards the periphery, whitish to creamy centrally, mouse grey at the margin, with conspicuous submerged growth, yellow pigment diffusing into the agar, reverse creamy or yellow. Sporulation abundant on all media, conidia formed on aerial as well as vegetative hyphae immersed in the agar.

Description in culture.

Asexual morph. On PCA, colonies effuse, mycelium composed of hyphae 1.5–3.5 (– 4) μm wide, cylindrical, subhyaline to olivaceous brown, septate, branched. Conidiophores micronematous, reduced to undifferentiated hyphal branches or single conidiogenous cells. Conidiogenous cells 4.5–12 × 3.5–6.5 (– 8.5) μm, holoblastic, conidial secession schizolytic, terminal or intercalary, inconspicuous, subhyaline to olivaceous brown, determined, smooth. Conidia dry, terminal, solitary, of various shapes: cylindrical with usually transverse septa 55–85 (– 104) × 14–19 (– 25) μm (mean ± SD = 75.6 ± 15.3 × 18.2 ± 3.6 μm), mostly ellipsoidal, subglobose, clavate, or irregular in shape and multicellular (dictyoconidia) 31.5–63.5 (– 77) × 20.5–27.5 (– 37) μm (mean ± SD = 50.2 ± 11.7 × 22.8 ± 2.4 μm), brown to dark olivaceous brown, smooth, but some conidia appeared finely rugose, with a pore 1–1.5 μm diam. in each cell, slightly constricted at the septa, dark brown, darker at the septa, basal cell clavate or somewhat ellipsoidal, subhyaline to pale olivaceous brown. Initially, conidia possess only transverse septa and are slightly coiled; upon maturation, longitudinal septa may develop, as well as additional cells formed in multiple planes, giving rise to more compact structures. Sexual morph. Not observed.

Additional specimen examined.

CZECHIA • Karlovy Vary Region, Cheb district, Soos National Nature Reserve near Františkovy Lázně ; slightly saline soil (pH 6.8); 2005; leg. & isol. M. Hujslová M. H. 158 (paratype PRA -22497 dried culture on MLA, culture CCF 3787 View Materials = CBS 153584 View Materials ) .

Habitat and geographical distribution.

Halomyrma pluriseptata was isolated from slightly saline inland soils (pH 6.8–7.2) in Czechia. According to GlobalFungi, H. pluriseptata has a broad geographical distribution, spanning from tropical to temperate climatic zones. Identical ITS sequences were found in 71 samples from aquatic and terrestrial habitats. Among aquatic biomes, H. pluriseptata was identified in marine salt marsh sediments in the UK ( Alzarhani et al. 2019) and Massachusetts, USA ( Lynum et al. 2020), as well as in marine sediments and roots of the seagrass Zostera marina in Croatia and Alaska, USA ( Ettinger et al. 2021). Additional marine records include occurrences in the neritic benthic zone in Sweden ( Retter et al. 2019). In freshwater environments, the fungus was found in lake sediments in China ( Zhang et al. 2021) and in Potamogeton sp. roots in California, USA ( Ettinger et al. 2021). A notable occurrence was also recorded in the rhizosphere soil in a hypersaline lake in China ( Luo et al. 2021), suggesting its adaptability to high-salinity freshwater systems. In contrast, H. pluriseptata was less frequently recorded in terrestrial biomes. It was identified in grassland soils in the UK ( George et al. 2019) and Denmark ( Frøslev et al. 2019), as well as coastal dune soils within wetland ecosystems in Canada ( Roy-Bolduc et al. 2015). Further occurrences include sediments from a shrubland biome in California, USA ( Lin et al. 2021), and soil samples from cropland fields in China ( Zhao et al. 2018) and the Netherlands ( van Rijssel et al. 2022). In other anthropogenic environments, the fungus was detected in plantation rhizosphere soil in China ( Huang et al. 2020) and topsoil in Poland ( Okrasińska et al. 2022), indicating its ability to persist in disturbed habitats.

Notes.

Hujslová et al. (2010) documented four strains of Lulwoana sp. ( CCF 3787 , CCF 3788 , M. H. 585, and M. H. 630) from saline soils. However, a BLASTn search of their published sequences indicated that strain M. H. 585 (GenBank accession FJ 430720 View Materials ) is affiliated with the Magnaporthaceae , while the other three isolates have affinity with the Lulworthiales . Consequently, two strains, CCF 3787 and CCF 3788 , were included in our study and are now recognised as H. pluriseptata , while strain M. H. 630 was unavailable for examination.

The cultural characteristics and description of H. pluriseptata are based on the ex-type strain CCF 3788 . While both strains shared identical ITS, LSU, and SSU rDNA sequences and exhibited comparable conidial morphology, they displayed differences in cultural characteristics. The non-type strain CCF 3787 demonstrated slightly faster growth on MLA, OA, and PCA (i. e. 50–52 mm in diam. on CMD, 44–46 mm on MLA, 62–64 mm on OA, 48–55 mm on PCA, and 24–25 mm on PCASW) within the same incubation period. Additionally, the ex-type strain CCF 3788 produced pigments that diffused into the agar: golden-yellow on OA and yellow on PCA and PCASW, whereas CCF 3787 did not exhibit pigment production on any tested medium.

Additionally, PDA and PDA supplemented with NaCl were used to further assess the growth and salt tolerance of H. pluriseptata ( CCF 3788 ) under in vitro conditions. Colony morphology on PDA was comparable to that observed on CMD, MLA, OA, PCA, and PCASW, exhibiting abundant aerial mycelium and reaching 40–52 mm diam. in 2 wk. In contrast, growth on PDA with added NaCl was significantly reduced, with colonies reaching only 6–9 mm in diam. in 2 wk. Hujslová et al. (2010) examined the effects of pH and salinity on the growth of CCF 3787 and CCF 3788 using soil agar supplemented with rose Bengal and glucose.

The multicellular brown conidia of Halomyrma resemble those of Moromyces ( Abdel-Wahab et al. 2010) , a genus that currently includes a single species, M. varius .