Hydnellum illudens (Maas Geest.) 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 : 245-246

Hydnellum illudens (Maas Geest.) Nitare , comb. nov.

MycoBank MB 837988. Figs 5A‒D , 9C .

Basionym: Sarcodon illudens Maas Geest., Proc. K. Ned. Akad. Wet. , Section C 79 (3): 285. 1976.

Synonym: “ Sarcodon pseudoglaucopus ”, Nitare nom. prov. in Nitare & Högberg (2012).

Misapplication: Sarcodon glaucopus sensu Nitare, 2006 , non Maas Geesteranus & Nannfeldt, 1969.

Selected illustrations (as “ Sarcodon pseudoglaucopus ” Nitare nom. prov.): Nitare & Högberg (2012: fig. 9A‒F).

Typus: France, Vendée, Saint-Hilaire-de-Talmont , ” Le Veillon ”, under an old Quercus ilex , 4 Nov. 1973, J. Boiffard L.09111973 (holotype).

Description: Basidiomata terrestrial, stipitate, fleshy and compact, single or concrescent. Pileus 70‒120 mm, convex to plano-convex, centrally somewhat depressed, ochraceous to fulvous brown, sometimes darker in the middle. Cuticle initially slightly tomentose, dry, first loosely covered by a thin cottony tomentum-layer of ephemeral whitish to pale rose hyphae (mostly whitish, but sometimes with slightly pinkish tints, ofen seen only in the expanding margin), with age becoming smooth, more or less glabrescent, from the centre more or less cracked into areoles and small adnate scales. Stipe 40‒60 × 15‒30 mm, above concolourous with the pileus, tapering downwards with a short rooting point, at the base white-tomentose or greyish blue to olivaceous grey (usually only at the rooting point, but sometimes developing a blue-grey base of the stipe). Spines strongly decurrent, but rarely reaching the middle of the stipe, up to 5 mm long, crowded, at first pallid, then becoming yellowish brown, when dried yellowish to ochraceous. Flesh not zoned, when fresh pale greyish, when dry (exsiccates) yellowish to ochraceous. Smell subfarinaceous, taste at first strongly farinaceous, mild or slightly acid or bitterish, afer a short while leaving a more intensely bitter taste with farinaceous components. Chemical reaction. When adding 3 % KOH on dry specimens, only the pileipellis (not the flesh) immediately changes colour to charcoal black. Hyphal system monomitic, all hyphae simple septate, spine trama hyphae up to 7 µm wide. Basidia clavate, with four sterigmata. Basidiospores pale brownish, globose or irregularly subglobose, tuberculate, with oblique apiculus, 4.7‒5.7(‒6.1) × 3.5‒4.5 µm, x = 5.2 × 4.0 µm, Q = 1.2‒1.5 (n = 3/90, measurements from the lateral side without tubercles), tubercles numerous, 0.4‒0.9 µm high, with rounded, flat-topped or exsculpate apices.

Ecology and distribution: Associated with Picea , Pinus or Quercus on calcareous or somewhat base-rich soils, ofen in sandy and dry places. In addition to the type locality in France it is known from calcareous ground in several districts in Sweden within the hemiboreal, southern boreal and middle boreal vegetation zones. It is confirmed also from southern to central Norway, Estonia, Switzerland, and Italy. A sequence (UDB024054) deposited in the UNITE database under the name Sarcodon imbricatus proved to be this species. The sequence was generated from a basidioma collected in conifer forest in NW British Columbia, Canada, making it the first report of Hydnellum illudens from North America.

Additional specimens examined: Italy, Puglia, Bari, Casamasella 14 km E of Maglia, old forest of Quercus ilex on calcareous soil, 6 Jan. 2007, E. Arnolds GB-0195786 ; Sardinia, Baldo, near Quercus suber, Cistus, Arbutus , 12 Nov. 2006, C.A. Hobart K(M)197492 (as S. cyrneus ) . Norway, Nord-Trøndelag, Steinkjer, Kalvøya, on soil with Pinus sylvestris, H. Holien , O-F-68659 ; Hedmark, Hamar, Furuberget nat. res., K. & E. Bendiksen O-F-76340 ; Viken, Ringerike, SW of Ultvedt, on soil in conifer forest, G. Gaarder O-F-242769 ; Ultveitvatnet nat. res., on soil in conifer forest, 25 Sep. 2010, S. Svantesson GB-0195937 ; Ultvedtåsen, calcareous Pinus forest, 16 Sep. 2016, T.E. Brandrud & B. Dima O-F-256728 ; Nordbyåsen, calcareous Pinus forest with some Picea , 20 Sep. 2016, T.E. Brandrud & B. Dima O-F-256727 . Sweden, Dalarna, Rättvik, Rättviksheden, “Gropen”, sandy Pinus heath, 5 Sep. 2004, J. Nitare GB-0195825 (fig. 9E & F in Nitare & Högberg 2012 ; ITS1 JX999975 ) ; Kalkverket SO, lichen-rich Pinus forest, 21 Aug. 2010, E. Larsson GB-0195721 ; Enån nat. res., Kungshol, sandy Pinus heath, 7 Sep. 2018, E. Larsson GB-0195723, GB-0195724 ; Gotland, Gothem, Åminne, Tjälders, on soil in mixed conifer forest on limestone, 23 Aug. 2005, J. Nitare GB-0195803 (ITS: 1 JX999984 ) ; 26 Sep. 2011, J. Nitare GB-0195649 ; Gästrikland, Gävle, Limön, Oxharen, mixed conifer forest, 18 Aug. 2012, L. Andersson & T. Fasth GB-0195651 ; NE of the café, Picea forest with some Pinus on diabase, 18 Aug. 2012 L. Andersson & T. Fasth GB-0195808 ; Limön 18 Aug. 2012, L. Andersson & T. Fasth GB 0195652, GB-0195653, GB-0195654, GB-0195655 ; Uppland, Älvkarleby, Billudden, Brämsand, on soil in calcareous sandy Pinus sylvestris forest, 12 Sep. 2007, J. Nitare GB-0195818 (fig. 9A in Nitare & Högberg 2012 ; ITS: 1 JX999985 ) ; 10 Oct. 2010, G. Aronsson GB-0195650 10 ; 14 Sep. 2009, J. Nitare GB-0195819 (fig. 9B & 9C in Nitare & Högberg 2012) ; Västland, Östervret, calcareous Picea forest, 16 Sep. 2016, J. Nitare GB-0195802 ; Öland, Böda, Böda kronopark, Pinus forest on windblown coastal sand-dunes, 8 Oct. 2007, E. Arnolds GB-0195787 .

Notes: This species differs macroscopically from Hydnellum scabrosum , H. fagiscabrosum and H. glaucopus by its ochraceous to fulvous brown cuticle (almond-brown or like café-au-lait) without copper-rufous (reddish) or violaceous colours and in dried exsiccates by its yellowish-ochraceous flesh and hymenium (spines). Both H. illudens and H. scabrosum can associate with Pinus , but H. illudens is found on base-rich soils whereas H. scabrosum is found mostly on acidic soils. Hydnellum illudens usually produces smaller and more compact and sturdier basidiomata compared to H. scabrosum . Hydnellum glaucopus can also be distinguished from the others by its smaller basidiospores which are 4‒4.5 µm, evenly subglobose and ornamented with rather slender evenly spread spines that are rarely twinned. By contrast, the larger basidiospores (up to 6.5 µm long) of H. fagiscabrosum , H. illudens and H. fagiscabrosum are slightly irregular and ornamented with rather coarse, frequently twinned (exsculpate) spines.

Maas Geesteranus (1976) regarded H. lepidum (as Sarcodon ) as the most closely related species.This observation is confirmed by the molecular phylogeny where the two species cluster together with high support.

Since its description from a single specimen the species has been little reported and seemingly ignored or misunderstood by European mycologists. The specimens we have sequenced were either not fully identified or assigned to Sarcodon cyrneus , S. fennicus , S. glaucopus , S. regalis , S. scabrosus , S. versipellis or to the provisional name “ S. pseudoglaucopus ”.

Two sequenced Italian specimens(GB-0195786,K(M)197492) were collected under Quercus ilex and Q. suber , respectively, which is also the normal habitat for Sarcodon cyrneus . The possibility that H. illudens can associate with Quercus trees implies that ecology alone may not suffice to separate H. illudens from H. lepidum . See also notes to H. nemorosum below.

Figures

Fig. 5. A. Hydnellum illudens TU106275 (UDB003274), photo V. Liiv. B. H. illudens GB-0195724. C. H. illudens TU106475 (UDB015699), photo V. Liiv. D. H. illudens GB-0195818. E. Hydnellum scabrosum TU106993 (UDB015662), photo V.Liiv. F. H. scabrosum TU106280 (UDB003279), photo V. Liiv.

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.