Hohenbuehelia filicina Bulyonk., D. Ageev et L.B. Kalinina, 2023

Kalinina, Lyudmila B., Ageev, Dmitry V. & Bulyonkova, Tatiana M., 2023, Hohenbuehelia filicina sp. nov. (Agaricales, Basidiomycota), from Southwestern Siberia, Russia, Phytotaxa 600 (5), pp. 272-280 : 275-277

Hohenbuehelia filicina Bulyonk., D. Ageev et L.B. Kalinina sp. nov. ( Fig. 1 )

MycoBank #847050

Diagnosis:—small, uniformly white pleurotoid basidiomata with round or auriculiform pileus and eccentric or lateral stipe up to 25 mm long and live rhizomes of ostrich ferns as substrate differ the H. filicina from other known species of the genus.

Holotype:— RussIA, Southwestern Siberia, Novosibirsk Oblast, vicinity of Akademgorodok , N54.850716°, E83.130592°, 30 July 2022, D.Ageev LE F-332234 (holotype LE F!, GenBank nrITS – OQ102434), on live Matteuccia struthiopteris ferns.

Etymology:—belonging to ferns, reflecting the ecology of the type species.

Basidiomata small. Pileus round or auriсuliform, 5–10 mm in diameter, planoconvex to plane with slightly incurved margin, sometimes with a slight depression, white (RAL 9003). Lamellae crowded, narrow, whitish (RAL 9016), somewhat beige in exsiccate (RAL 9010, 9001). Stipe lateral or strongly eccentric, cylindrical, 3–25 mm long, 1.5–2.5 mm wide, concolorous with the pileus ( Fig. 1b, 1c, 1d ). Flesh white (RAL 9003). Odor mild, fungal, taste unrecorded.

Basidiospores (3.2) 3.21–3.7 (3.9) × (2.3) 2.4–3.06 (3.1) µm (Q = 1.2–1.38, N = 33), broadly ellipsoid to subglobose, smooth, hyaline, inamyloid, very scarce in all examined specimens ( Fig. 1e 4). Lamellar trama of hyaline, cylindrical subparallel hyphae 3–6 µm wide; subhymenium of interwoven hyphae 2–3 µm wide. Basidia narrowly clavate to almost cylindrical, 4-spored (12.4) 12.8–15.8 (16.4) × (2.9) 3.1– 4.1 (4.3) µm ( Fig. 1e 3). Cheilocystidia abundant, narrow, cylindrical or slightly capitulate, appearing as a frill of extensions of lamellar trama (11.7) 13.6–25.3 (30.7) × (1.7) 1.9–2.7 (13.2) µm ( Fig.1e 5). Pleurocystidia rather numerous, typical for the genus: narrowly fusiform to fusiform, occasionally with constrictions in the lower half, thick-walled with 2–3 µm thick walls, with a pointed apex encrusted with transparent resinous material slightly yellowing in KOH, (35) 41.6–53 (128.3) × (0.6) 7– 9.7 (15.6) µm ( Fig. 1e1 ). Pileipellis a cutis of filamentous, loosely interwoven hyphae 1.2–2.4 µm wide ( Fig.1e 2 ). Clamp connections present in all tissues.

Habitat and known distribution:—Solitary and in small groups on bases (rhizomes) of live Matteuccia struthiopteris ferns, growing from the live central part, possibly parasitic; in native old-stand mixed, predominantly birch ( Betula pendula ) and aspen ( Populus tremula ) forests with tall forb herbaceous layer, preferring damp, shaded ravines and hollows; humidity requirements may be a limiting factor. Known from the Novosibirsk Oblast, Southwestern Siberia, Russia, locally not uncommon; possibly widely distributed but overlooked due to size, unconventional ecology and general rarity.

Material examined:— RussIA, Southwestern Siberia, Novosibirsk Oblast, vicinity of Akademgorodok , N54.849289°, E83.132515°, 21 June 2020, D. Ageev LE F-332233 (GenBank nrITS—OQ102433), on bases of live Matteuccia struthiopteris ferns ; same location, 22 July 2019, T. Bulyonkova LE F-332248 .

Figures

FIGURE 1. a—habitat. b—basidiomata (LE F-332233). c—basidiomata. d—basidioma in situ (LE F-332248). e—microstructures: 1— pleurocystidia, 2—pileipellis hyphae, 3—basidia, also basidioles (without sterigmata) shown, 4—spores, 5—cheilocystidia.

FIGURE 2. Phylogenetic tree of Hohenbuehelia filicina and allies derived from the nrITS dataset using ML analysis. The ML bootstrap support is shown above branches. For all taxa the GenBank accession numbers (nrITS) are presented. The specimen studied for this article is highlighted in bold. Scale bar indicates the mean number of nucleotide substitutions per site.