Hydnellum scabrosellum Nitare, 2021

Nitare, J., Ainsworth, A. M., Larsson, E., Parfitt, D., Suz, L. M., Svantesson, S. & Larsson, K. - H., 2021, Four new species of Hydnellum (Thelephorales, Basidiomycota) with a note on Sarcodon illudens, Fungal Systematics and Evolution 7 (1), pp. 233-254 : 250-251

Hydnellum scabrosellum Nitare sp. nov.

MycoBank MB 837987. Figs 8A‒C , 9G .

Etymology: Epithet derived from scabros [um] and - ellum (L. dim.) referring to “the small scabrosum ” (= Hydnum scabrosum Fr. ).

Typus: Sweden, Uppland, Börstil parish, Tvärnö , Tuskö, Tuskösundet nat. res. (“Återvändan”), in herb-rich conifer forest dominated by Picea abies with some scattered old Pinus sylvestris , on strongly calcareous moraine on the edge of an old abandoned mine-shaf, 60.22267 / 18.49009, 13 Sep. 2012, J. Nitare (holotypus GB-0195689 ; isotypi O, UPS); GenBank accession: MW144379 .

Description: Basidiomata terrestrial, stipitate, thin and slender, single or concrescent. Pileus 30‒60(‒100) mm broad, planoconvex to depressed, with undulating thin margin. Cuticle fibrillose and scaly, cracking up from the centre, at first rosy to pinkish, with whitish growing edge, with age becoming coppery or vinaceous reddish-brown to purplish-brown, with darkening blackish-brown scales in the centre. Stipe 30‒60 × 5‒10 mm, above ochraceous pinkish-brown or concolourous with the pileus, tapering downwards, at the base bluish-grey or blackishgreen under a white mycelial cover. Spines strongly decurrent, ofen reaching the middle of the stipe, up to 5 mm long, crowded, at first pallid and whitish, by age becoming yellowish brown, when dry yellowish to ochraceous. Flesh not zoned,fresh pale, when dry (exsiccates) yellowish-ochraceous brown. Smell subfarinaceous, taste bitterish. Chemical reaction. When adding 3 % KOH to dry specimens, only the pileipellis (not the flesh) immediately changes colour to charcoal black. Hyphal system monomitic, all hyphae simple septate, generative hyphae up to 10 µm wide. Basidia clavate, with four sterigmata. Basidiospores pale brownish, globose or irregularly subglobose, tuberculate, with oblique apiculus, 5.1‒6.6 × 3.4‒4.7 µm, av. = 5.8 × 4.0 µm, Q = 1.2‒1.7 (n = 3/90, measurements from the lateral side without tubercles), tubercles numerous, 0.6‒0.9 µm high, with prominent, rounded, flattened, flat-topped to exsculpate apices.

Ecology and distribution: Presumably ectomycorrhizal with conifers (mixed forest with Pinus and Picea , associated treespecies not exactly known but probably Pinus sylvestris ), strongly calciphilous. Mostly known from coniferous forests situated close to the coast (Gulf of Bothnia) in the province of Gästrikland and northern Uppland, east-central Sweden (at the northern limits of the hemiboreal vegetation zone). This so far Swedish species can be expected to occur in pine forests on calcareous ground around the Baltic Sea.

Additional specimens examined: Sweden, Gästrikland, Hamrånge, Bergby, Näset nat. res., calcareous conifer forest, 15 Sep. 2011, J. Nitare GB-0195807 ; Uppland, Börstil, Tvärnö, Tuskö, Tuskösundet,5 Sep. 2008, J. Nitare GB-0195806 (from the same spot as the holotype, fig. 12A in Nitare & Högberg 2012) ; Älvkarleby,Lanforsen, Tippön,calcareous Pinus sylvestris forest (with scattered Picea abies ), 20 Sep. 2013, G. Aronsson GB-0195791 ; Askön, calcareous Pinus sylvestris forest (with scattered Picea abies ), 13 Sep. 2013, G. Aronsson GB-0195792 ; Östergötland, Västra Tollstad, Omberg, Ombergsliden nat. res., on soil in calcareous Picea abies forest with Pinus sylvestris and Betula sp. , 13 Sep. 2016, E. Larsson GB-0195736 .

Notes: Among the hydnoid fungi associated with conifers, Hydnellum scabrosellum is most similar to H. scabrosum but has smaller and slenderer basidiomata and looks like a dwarf form of the latter species. The size difference is particularly obvious when considering the stipe diameter which rarely exceeds 1 cm in H. scabrosellum but is usually 2‒5 cm in mature specimens of H. scabrosum . The yellowish-ochraceous hymenium and flesh (when dry) and the occurrence on base-rich soil, also differs from the non-calciphilous H. scabrosum . The coastal region in Gästrikland, where most collections were made, is characterized by its extremely calcareous-rich soils (moraine), depending on the geological features and recent land uplif during the postglacial period.

Figures

Fig. 8. A. Hydnellum scabrosellum, young basidiomata from the type locality, GB-0195806. B. H. scabrosellum holotype, mature basidiomata, GB- 0195689. C. H. scabrosellum GB-0195791, photo G. Aronsson. D. H. scabrosellum, collecting site for GB-0195791, photo G. Aronsson.

Fig. 9. Hydnellum basidiospores. A. H. fagiscabrosum (holotype, GB-0195805). B. H. glaucopus (GB-0195722). C. H. illudens (GB-0195937). D. H. lepidum (GB-129373). E. H. nemorosum (O-F-242352). F. H. roseoviolaceum (holotype. GB-0195936).G. H. scabrosellum (holotype, GB-0195689). H. H. scabrosum (GB-0195731). Scale bar = 5 µm.