Cortinarius flaureifolius Niskanen, Liimat. & M. E. Sm., sp. nov.

Index Fungorum number: IF 900305; Mycobank number: MB 900305; Facesoffungi number: FoF 14862; Figs. 1a, 2a, 3

Etymology – Derived from the name of the sister species Cortinarius aureifolius and the location Florida.

Holotype – K-M 001434094.

Pileus 1.5–3.5 cm in diam, convex to plane, tomentose fibrillose, brown. Lamellae medium spaced, at first yellow, later brown. Stipe 2–4 cm long, up to 0.4 cm thick at the apex, cylindrical, at first pale greyish white silky fibrillose, later pale yellowish to ochre brown. Context not recorded. Universal veil ochre (brown), quite sparse. Mycelium not recorded. Odour indistinct. Basidiospores 11–13×3.5–4 µm, boletoid, almost smooth. Basidia hyaline. ITS sequence (GenBank ON843398, ex holotype) distinct from other members of C. subgen. Dermocybe and with 92% similarity to the closest known species C. aureifolius.

Habitat and distribution – With Pinus on sandy soil and so far only known from Florida, USA.

Material examined – USA, Florida, Melrose, OrdwaySwisher Reserve, in sandy soil with mostly pines but some oaks, 1 December 2014, M. E. Smith, MES811, 001434094 (holotype in K-M; isotype in FLAS).

GenBank number – ITS=ON843398.

Notes – In the field the species looks like a representative of Cortinarius sect. Dermocybe or an Inocybe. The species is easy to recognize by the narrow, boletoid basidiospores. The sister species C. aureifolius has yellow orange to ochraceus orange lamellae when young. For an unambiguous identification ITS sequence is recommended.

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