Wilhelmdebeerea oxyuri M. Kolarik 2026, sp. nov.

Wilhelmdebeerea oxyuri M. Kolařík sp. nov. Fig. 7 Etymology. The epithet oxyuri refers to the specific beetle associated with this fungus. Diagnosis. Wilhelmdebeerea is a monotypic genus and the species and genus diagnoses are identical until additional species are found. Type. SLOVAKIA • Zvolen region, Tŕnie, 48.627397°N, 19.029675°E; alt. 665 m.; from larva of Treptoplatypus oxyurus feeding in the base (40 cm diam) of a decaying Abies alba; 10. June 2024; leg. M. Knížek, J. Vakula, M. Zúbrik, isol. M. Kolařík Tox- 2 (holotype PRM 963297 dried culture CCF 6802 on MEA, isotypes PRM 963298, 963299, dried culture CCF 6802 on MEA with cycloheximide, culture ex type CCF 6802). Another representative strain – CCF 6803, the same source as CCF 6802, but isolated from mycangia of a female adult. Sequence accessions: ITS - PX 523832, LSU - PV 061845,, rpb 2 - PV 067587, tef 1-α - PV 067588, tub 2 - PV 067589, WGS - ERZ 28561635. Description. The species description is based on the type strain. The strain CCF 6803 has the same morphology. Cultural characteristics after 14 d: Colonies with optimal growth at 25 ° C (33 mm, 14 d). Growth at 5 ° C 8.5 mm, no growth at 35 ° C. Colonies at 25 ° C are cream with light brown zones, and the margin is narrow. Hyphae are hyaline to olive brown in colour, smooth, submerged in the medium; aerial mycelium is sparse, cream coloured. The strain grows well (32 mm in 14 d) on MEA with 500 mg / L of cycloheximide. Sexual morph is not observed. Asexual morph on MEA is mononematous, of the hyalorhinocladiella-like and leptographium-like type. Hyalorhinocladiella - like conidiophores, arising directly from submerged or aerial mycelium, are smooth, hyaline, micronematous or semimicronematous, 5.0–45.0 × 1.0–3.0 µm; conidia are variable in shape, hyaline, cylindrical, allantoid to broadly ellipsoidal, or clavate (1.5 –) 2.7–3.9 ± 0.66 (– 4.8) × (0.8 –) 1.0–2.0 ± 0.30 (– 3.0) µm. Leptographium - like anamorph. Conidiophores are macronematous, light olivaceous or olivaceous, smooth, arising from substrate hyphae, solitary or loosely compacted, resembling cream sporodochia, (100 –) 120–230 (– 450) μm in length. Stipe erect, olivaceous, 3–5 septate, (60 –) 80.0–180.0 (– 280.0) μm long and (3.0 –) 4.8–5.2 (– 6.2) μm wide at the base; basal cell is often swollen with a foot-like cell. Conidiogenous apparatus is (50.0 –) 55.0–65.0 (– 200.0) μm long (excluding conidial mass), consisting of 3–5 (mostly 3) series of branches-type B (more than two branches) (Jacobs and Wingfield 2001). Primary branches are (14.0 –) 15.5 – + 18.5 (– 24.0) × (4.0 –) 4.4 (– 5.0) μm in size. Conidiogenous cells are hyaline, tapering from base to apex, (6.0 –) 9.0 (– 15.0) × (0.7 –) 1.2 (– 1.3) μm in size. Conidia are hyaline, clavate (2.6 –) 3.3–5.9 ± 0.68 (– 7.5) × (1.1 –) 1.5–2.3 ± 0.25 (– 2.9) μm in size, accumulating around the conidiogenous apparatus as a creamy mucilaginous mass. Chlamydospores are absent. Distribution. Wilhelmdebeerea oxyuri was cultured from a single locality in Slovakia. Further investigations are required to determine the strength of its association with T. oxyurus. Based on GlobalFungi data, the species has been detected in 45 deadwood substrate samples from boreal forest ecosystems in Finland and Russia (Mikryukov et al. 2021; Korhonen et al. 2022) (see Biogeography section, Suppl. material 12). The host records suggest that W. oxyuri may be common, but poorly sampled, in coniferous wood in boreal Eurasia, not only in Abies, the exclusive host of T. oxyurus. Its distribution overlaps with B. sasensis and C. schatavii. Notes. The genomic sequence of monosporic ex-type strains contains both MAT gene idiomorphs, and the species can be considered homothallic. In particular, it possesses the MAT 1-1 gene sequence, which has an 83 % identity, and the MAT 1-2 gene, which has an 84 % identity, to the reference sequences of Ophiostoma montium.