Phlegmacium pallidocaeruleum Niskanen Liimat. & Bojantchev, sp. nov.
Index Fungorum number: IF 900311; Mycobank number: MB 900311; Facesoffungi number: FoF 14868; Figs. 1b, 2b, 3
Etymology – Named for the general coloration of the basidiomes.
Holotype – K-M 001434120.
Pileus 4.5–7.5 cm in diam, at first hemispherical, then low convex to almost plane, innately fibrillose, ochraceous in the middle, silvery bluish grey towards margin, ochraceous part enlarging with age, viscid, somewhat hygrophanous striate. Lamellae subcrowded to crowded, bluish grey, adnexed to adnate. Stipe 5–9 cm long, 1–2 cm thick at the apex, up to 3 cm at the base, with a rounded bulb, at first pale greyish blue, later more whitish, becoming brownish ochraceous when handled or gaining brownish ochraceous spots with age. Context when young bluish white marbled hygrophanous in the pileus and upper part of the stipe, white at the lower part of the stipe, when old white or yellowish white in the pileus and the base of stipe, greyish blue at the apex of stipe. Universal veil white at the very base of the stipe/bulb. Mycelium white, often forming strands. Odour indistinct. Basidiospores 8.5–10×5–6 µm, obovoidly ellipsoid, moderately verrucose, somewhat more strongly at the apex. Basidia hyaline in 5% KOH. ITS sequence (GenBank ON843424, ex holotype) distinct from other members of Phlegmacium and with 98% similarity to the closest known species P. aurescens.
Habitat and distribution – In mixed coniferous forests and so far known from California, USA.
Material examined – USA, California, Mendocino Co., Caspar, Caspar cemetery, mixed conifer dominated forest with Tsuga, Abies and Picea, 22 November 2012, K. Liimatainen, T. Niskanen 12-098, 001434120 (holotype in K-M; isotype in H).
GenBank number – ITS=ON843424.
Notes – Phlegmacium pallidocaeruleum is a typical member of the P. sect. Caerulea. It has pallid blue colours, the pileus is innately fibrillose and becoming more ochraceous from the centre with age, and the basidiospores are ellipsoid. The sister species P. aurescens, currently known from Washington, USA, has less bluish basidiomes and longer (10–11×5.5–6.5 µm) basidiospores.
Figure 1 – Basidiomes of the species of the genera Phlegmacium and Thaxterogaster. a Phlegmacium fennicum (K-M 001434119, holotype). b Phlegmacium pallidocaeruleum (K-M 001434120, holotype). c Thaxterogaster americanoporphyropus (K-M 001434121, holotype). d Thaxterogaster obscurovibratilis (K-M 001434124, holotype). Photographs: a Tapio Kekki, b–d Kare Liimatainen
Figure 2 – Basidiomes of the species of the genera Phlegmacium and Thaxterogaster. a Phlegmacium fennicum (K-M 001434119, holotype). b Phlegmacium pallidocaeruleum (K-M 001434120, holotype). c Thaxterogaster americanoporphyropus (K-M 001434121, holotype). d Thaxterogaster obscurovibratilis (K-M 001434124, holotype). Drawings: Tuula Niskanen. Scale bars: 10 µm
Figure 3 – The best scoring RAxML tree of the genera Phlegmacium and Thaxterogaster based on the ITS region. Related sequences were retrieved from GenBank. Twenty-six specimens were included in the analysis of the ITS region which comprises 671 characters after alignment. The tree is rooted with Thaxterogaster. Estimated base frequencies were: A=0.246332, C=0.202234, G=0.200934, T=0.350500; substitution rates AC=1.534815, AG=3.904253, AT=1.485681, CG=0.452034, CT=6.187457, GT=1.000000, gamma distribution shape parameter α=0.257017. 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