Pseudogymnoascus irelandiae Childress & Quandt, 2025

Childress, Mary K., Dragone, Nicholas B., Young, Benjamin D., Adams, Byron J., Fierer, Noah & Quandt, C. Alisha, 2025, Three new Pseudogymnoascus species (Pseudeurotiaceae, Thelebolales) described from Antarctic soils, IMA Fungus 16, pp. e 142219-e 142219 : e142219-

Pseudogymnoascus irelandiae Childress & Quandt sp. nov

Figs 3 , 4

Etymology.

Named after Abigail Ireland for her substantial contributions to the taxonomy of Pseudogymnoascus .

Type.

Antarctica • Cape Hallett , 72°19'16.57"S, 170°13'41.58"E, 2 m, from soil, 14 Dec 2004, coll. B. Adams. Holotype 273 ASP 01, stored in a metabolically inactive state in the CFMR Herbarium, while ex-type metabolically active material is stored in the Reference Culture Collection at the CFMR .

Description.

On CMA and PDA hyphae branched, septate, hyaline, smooth, 0.9–1.9 μm wide. Coiled hyphae sometimes found on CMA. Hyphae form tight bundles of 3–11 hyphae on PDA. Racquet hyphae absent. Fertile hyphae bearing aleurioconidia, sessile or stalked. Arthroconidia not observed. Conidiophores abundant, solitary, usually curved, occasionally erect, arising in acute angles with the main axis, hyaline, smooth, usually bearing verticils of two to four branches arising from the stipe at an acute angle. Conidiophores more abundant on CMA than PDA. Aleurioconidia are pyriform to clavate or obovoid with a broad truncate basal scar, 2.8–4.6 × 1.7–3.2 μm (av = 3.7 × 2.5 μm, n = 50), in conidiophores separated by connective cells. Intercalary conidia are rare, pyriform to clavate, or subglobose, 2.4–3.9 × 1.6–2.4 μm (av = 3.1 × 2.0 μm, n = 11), in conidiophores separated by connective cells. Ascomata absent.

Culture characteristics.

On OA, colonies reach 44 mm in diameter after 28 days at 15 ° C, round, appressed, colorless to white, consisting of immersed and hyaline hyphae, small spots of white cottony aerial mycelium emerging throughout the colony, exudates and diffusible pigments absent; reverse white. On CMA, colonies reach 36 mm in diameter after 28 days at 15 ° C, round, flat, floccose, gray to white, forming irregular concentric rings, filamentous margin, exudates and diffusible pigments absent; reverse white, brown to yellow at center. On SDA, colonies reach 43 mm in diameter after 28 days at 15 ° C, irregular, slightly raised, floccose, shallow radial grooves, white to gray, margin filamentous and white, sparse exudates in the form of small transparent and colorless droplets, diffusible pigments absent; reverse light brown to yellow. On PDA, colonies reach 35 mm in diameter after 28 days at 15 ° C, round, slightly raised, floccose, white, white cottony aerial mycelium emerging throughout the colony, exudates in the form of transparent and colorless droplets, diffusible pigments absent; reverse tan to cream. Growth occurred at 5 ° C and 15 ° C, with very minimal growth at 25 ° C; Optimum growth was observed at 15 ° C. No culture attenuation was observed.

Distribution.

Cape Hallett, Antarctica.

Ecology / substrate.

Cultured from Antarctic soil.

Genbank accession numbers.

ITS = PQ 453553, LSU = PQ 453558, MCM 7 = PQ 497089, RPB 2 = PQ 497096, TEF 1 = PQ 497101

NCBI BioSample genome accession.

SAMN 40283453 .

Note.

Pseudogymnoascus irelandiae has been placed as a member of clade K (Figs 1 , 2 ), which also includes unidentified strain A 07 MA 10 ( Minnis and Lindner 2013). Both Pseudogymnoascus irelandiae and strain A 07 MA 10 have a TEF 1 amino acid insert at the same position that no other Pseudogymnoascus species have ( Minnis and Lindner 2013). Fig. 1 shows clade K as sister to clade I, however the placement of clade K in relation to other clades has low bootstrap support. The placement of this clade has continued to have low support since it was originally classified in Minnis and Lindner (2013). However, according to Fig. 2 , there is strong bootstrap support for clade K being sister to clades B, E, F, G, H, I, J, Q; but data are missing for clades A, C, and D to confirm this placement. Pseudogymnoascus irelandiae can be distinguished from species in clade B by its presence of coiled hyphae. And differentiated from P. lanuginosus and P. fujianensis in clade E by smaller aleurioconidia size ( Villanueva et al. 2021; Zhang et al. 2021). Within clade F, P. destructans ( Minnis and Lindner 2013) has asymmetrically curved conidia not observed in P. irelandiae . Clade G consists of P. palmeri , P. roseus , and P. rhousiogongylinus ( Wener and Cain 1970; Crous et al. 2019, 2020), all of which have ascomata while P. irelandiae does not. Pseudogymnoascus irelandiae differs from P. yunnanensis , P. guizhouensis , P. camphorae , P. cavicola , P. zhejianensis , and P. catensis in clade H based on its presence of coiled hyphae ( Zhang et al. 2020, 2021, 2023 b; Becker et al. 2023). Pseudogymnoascus irelandiae differs from P. hyalinus by its lack of coremia ( Daszewska 1924), and from P. botryoides and P. antarcticus in clade I with its lack of arthroconidia ( Villanueva et al. 2021; Zhang et al. 2023 b). Within clade J are P. guiyangensis , P. zongqii , and P. sinensis , in addition to undescribed strains 10 NY 09, MN-Mycosel- 7, 10 NY 08, and 21 IN 10 ( Minnis and Lindner 2013; Luo et al. 2016; Zhang et al. 2020, 2023 b). Pseudogymnoascus irelandiae has a smaller hyphal width than P. guiyangensis (0.9–1.9 μm vs 1.5–2.5 μm). Pseudogymnoascus zongqii lacks exudates on PDA whereas P. irelandiae has colorless exudates. Pseudogymnoascus irelandiae has white colonies on PDA whereas P. sinensis has a light pink center. Lastly, P. irelandiae differs from P. ramosus in clade Q in its larger colony diameter on PDA, OA, SDA, and CMA, lack of gregariously branching groups of conidiophores, and different exudate colors. Phylogenetically, P. irelandiae forms a well-supported independent lineage with strain A 07 MA 10, with a bootstrap value of 100, being the first described species in clade K. We are not able to confirm if strain A 07 MA 10 is conspecific with P. irelandiae as we don’t have access to this isolate to analyze its culture and microscopic characteristics; however, we do know that their isolation sources are quite different, as A 07 MA 10 was cultured from soil from bat hibernacula in Massachusetts, USA ( Minnis and Lindner 2013).

Figures

Figure 1. Maximum likelihood (ML) phylogenetic tree of Pseudogymnoascus based on the concatenated dataset of five genes (ITS, LSU, MCM 7, RPB 2, TEF 1). ML bootstrap values ≥ 70 are shown above branches. New species described here are highlighted in bold and red. The scale bar indicates 0.03 nucleotide changes per site.

Figure 2. ML phylogeny of Pseudogymnoascus based on an alignment of 1496 concatenated orthogroups with single-copy genes. ML bootstrap values ≥ 75 are shown above branches. New species are highlighted in bold and red. The scale bar indicates 0.09 amino acid changes per site.

Figure 3. Pseudogymnoascus irelandiae sp. nov. colony morphology at 5 ° C and 15 ° C after 28 days on CMA, OA, PDA, and SDA.

Figure 4. Pseudogymnoascus irelandiae sp. nov. A coiled hyphae B fertile hyphae bearing aleurioconidia C conidia D, E conidiophores. Scale bars: 10 µm.