Hygronarius californicus Niskanen, Liimat., Bojantchev & Ammirati, sp. nov.
Index Fungorum number: IF 900308; Mycobank number: MB 900308; Facesoffungi number: FoF 14865; Figs. 1a, 2a, 3
Etymology – The species was first found from California, USA.
Holotype – K-M 001434114.
Pileus 1.5–3.5 cm in diam, at first hemispherical, then low convex to almost plane, sometimes with a broad and low umbo, red brown, strongly hygrophanous. Lamellae medium spaced, pale brown. Stipe 4–6 cm long, 0.5–1.0 cm thick at the apex, cylindrical, yellowish brown to ochre brown fibrillose. Context yellow brown to red brown. Universal veil and cortina absent. Mycelium white. Odour indistinct. Basidiospores 6.5–7.5×5–5.5(–5.7) µm, somewhat obovoid-subglobose to very broadly obovoid-ellipsoid, moderately to almost strongly verrucose. ITS sequence (GenBank ON843418, ex holotype) distinct from other members of Hygronarius and with 98% similarity to the closest known species H. renidens.
Habitat and distribution – In mixed coniferous forests and so far known from North America: Alberta, British Columbia, California, Oregon and Washington.
Material examined – Canada, Alberta, Hinton, 05 September 2011, T. Niskanen 11–381, 001434115 (K-M). USA, California, Mendocino Co, Jackson Demonstration State Forest, crossing of the roads 408 and 409, mixed conifer dominated forest (Tsuga), 17 November 2012, T. Niskanen 12-080, 001434114 (holotype in K-M; isotype in H). Oregon, Detroit, Breitenbush, surroundings of the Breitenbush Hot Springs Retreat & Conference centre, mixed coniferous forest of Tsuga heterophylla and Pseudotsuga mentziesi with some Castanopsis chrysophylla, 12 October 2007, K. Liimatainen, T. Niskanen 07–482, 001434116 (K-M). Washington, Mount Baker, Easy Pass trailhead, coniferous forest (Tsuga heterophylla, Abies and some Picea engelmannii), 28 September 2009, K. Liimatainen, T. Niskanen 09-017, 001434117 (K-M).
GenBank numbers – TN12-080: ITS=ON843418; TN11-381: ITS=ON843419; TN07-482: ITS=ON843420; TN09-017: ITS=ON843421.
Notes – Hygronarius californicus is characterised by the red brown pileus, absence of universal veil, and small, obovoid-subglobose to very broadly obovoid-ellipsoid basidiospores. The spores are slightly longer than those in the North American-European sister species H. renidens (6–7×5–5.5 µm), but for an unambiguous identification an ITS sequence is needed. Hygronarius californicus belongs to the H. subgen. Hygronarius.
Figure 1 – Basidiomes of the species of the genera Cortinarius, Hygronarius and Mystinarius. a Cortinarius flaureifolius (K-M 001434094, holotype). b Cortinarius floridaensis (K-M 001434095, holotype). c Cortinarius subiodes (K-M 001434108, holotype). d Hygronarius californicus (K-M 001434114, holotype). e Mystinarius ochrobrunneus (CR 4064459, holotype). Photographs: a Matthew E. Smith, b–d Kare Liimatainen, e Joseph F Ammirati
Figure 2 – Basidiomes of the species of the genera Cortinarius, Hygronarius and Mystinarius. a Cortinarius flaureifolius (K-M 001434094, holotype). b Cortinarius floridaensis (K-M 001434095, holotype). c Cortinarius subiodes (K-M 001434108, holotype). d Hygronarius californicus (K-M 001434114, holotype). e Mystinarius ochrobrunneus (CR 4064459, holotype). Drawings: Tuula Niskanen. Scale bars: 10 µm
Figure 3 – The best scoring RAxML tree of the genera Cortinarius and Hygronarius based on the ITS region. Related sequences were retrieved from GenBank. Forty-nine specimens were included in the analysis of the ITS region which comprises 732 characters after alignment. The tree is rooted with Hygronarius. Estimated base frequencies were: A=0.242037, C=0.200516, G=0.214242, T=0.343206; substitution rates AC=1.323688, AG=3.480113, AT=1.611311, CG=0.756641, CT=4.952595, GT=1.000000, gamma distribution shape parameter α=0.362036. Maximum likelihood bootstrap values higher than 50% are given at the nodes. The holotype specimens retrieved from the GenBank are in bold and black. The new species are in bold and blue. The section of the species is indicated after the collection/GenBank no. of each specimen