Pluteus hubregtseorum G.M. Gates, Ševčíková & Borovička, 2021

Ševčíková, Hana, Borovička, Jan & Gates, Genevieve, 2021, Pluteus hubregtseorum (Pluteaceae), a new species from Australia and New Zealand, Phytotaxa 496 (2), pp. 147-158 : 151-154

Pluteus hubregtseorum G.M. Gates, Ševčíková & Borovička sp. nov. ( Figs. 3–4 )

Mycobank:—MB836055

Etymology:—named after Virgil and Jurie Hubregtse who first realised the novelty of the species during a study on Pluteus in Victoria, Australia ( Hubregtse & Hubregtse 2011).

Diagnosis:—Differs from Pluteus semibulbosus by its yellow to brownish gold pileus, lamellae and stipe often with yellow tinge, and distinctive ITS and EF1-α sequences.

Holotype:— AUSTRALIA. Tasmania, Hobart, Truganini track, 18 April 2013 leg. G. Gates ( HO 585031). On a well-rotten piece of Eucalyptus wood on a forest floor of a wet sclerophyll gully.

Isotype:—BRNM 825719. GenBank: MN918531 (ITS and LSU). EMBL-Bank: LR757898 (EF1-α).

Description:— Pileus 15–45 mm diam, 5–8 mm high, hemispherical or convex to plano-convex, dry, translucentstriate at least at margin, velutinous at centre, squamulate to finely granulate, golden yellow or deep brownish gold sometimes with golden brown to raw umber brown hue at centre, margin straight and entire. Lamellae free to almost free, ventricose, 2–10 mm deep, whitish, later pale pink to flesh pink, sometimes with golden yellow tinge at least near pileus, margin fimbriate, concolorous with faces, thin, crowded, 1–2 tiers of lamellulae. Stipe 22–52 × 2–5 mm, centrally attached, cylindrical, slender, mostly equal, slightly swollen at base up to 7 mm wide, brittle, pruinose, finely squamulose or longitudinally fibrillose, with a silky sheen, sometimes longitudinally striate, (pale) golden yellow, sometimes darker at base, whitish at apex. Sometimes, stipe is hirsute at base with white or yellow fibrils and white or yellow fuzzy tomentum. Context solid, cream or yellowish, yellow at base. Odour none or faintly fungoid, taste not determined.

Basidiospores 5.5–8.0(8.5) × 5–6.5(7.0) μm, avl × avw = 7.2 × 6.0 μm, Q = 1–1.4, avQ = 1.27, broadly ellipsoid, subglobose or globose. Basidia 20–39 × 7–14 μm, 4-sterigmate, cylindrical, clavate to subfusiform. Pleurocystidia moderately abundant, (35)55–72(80) × (14)16–25(27) μm, narrowly to broadly lageniform, fusiform to broadly fusiform, sometimes with longer pedicel or/and neck, rarely utriform to spathulate, thin-walled, colourless. Lamella edge sterile. Cheilocystidia (22)30–80(95) × (7)9–25(41) μm, broadly ventricose to ventricose, broadly fusiform to fusiform, clavate, rarely lageniform, thin-walled, colourless or with very pale yellow intracellular pigment. Pileipellis a cutis with transition to a trichoderm, terminal hyphae (70)80–150(240) × 10–26 μm, cylindrical to narrowly clavate with obtuse apex, with yellow to yellow-brown intracellular pigment. Stipitipellis a cutis of (3)4–15(20) μm wide, cylindrical, thin-walled hyphae with very pale yellow intracellular pigment or colourless. Caulocystidia in tufts, 16– 95(110) × (6)9–20(22) μm, cylindrical to narrowly clavate, rarely subfusiform, thin-walled, colourless or with pale yellow or pale brown intracellular pigment. Clamp connections absent in all studied tissues.

Ecology and distribution:—On decaying wood, in wet sclerophyll forest dominated by Eucalyptus trees, and an understory of Pomaderris apetala and Olearia argophylla or in rainforest dominated by Nothofagus cuninghamii and Atherosperma moschatum .

Additional collections examined:— AUSTRALIA. Tasmania. Huon Pine Walk, on small branch on forest floor of rainforest dominated by Nothofagus cunninghamii and Atherosperma moschatum 13 January 2004 leg. G. Gates and D. Ratkowsky (HO 585042, BRNM825721; GenBank MN918529 ); Wielangta, in a wet eucalypt forest, 19 February 2005, leg. G. Gates and D. Ratkowsky (HO 585041, BRNM825722; GenBank MN918530 , LR757897 ); Leap Loop, in a wet eucalypt forest, 21 May 2011, leg. G. Gates and D. Ratkowsky (HO 585032, BRNM 825723; GenBank MN918532 ); Victoria, Mortimer Nature Trail, Bunyip State Forest, wet sclerophyll forest, on rotting log of Eucalyptus cypellocarpa , 13 December 2009 leg. J. and V. Hubregtse (MEL2341015); ibid 8 August 2010 J. and V. Hubregtse (MEL2341016).

Pluteus cf. hubregtseorum: Truganini track, 2 September 2009, leg. G. Gates ( HO 585044, BRNM 825720 )

Pluteus hubregtseorum f. horakianus f. nov. Ševčíková, Daley, Borovička & G.M. Gates

Mycobank: MB 836056

Etymology:—Named in honour of the renowned mycologist Egon Horak, whose excellent work is the basis for recent studies of genus Pluteus in New Zealand.

Diagnosis:—Differs from Pluteus hubregtseorum f. hubregtseorum by its light to dark brown, sometimes darker and radially wrinkled pileus; whitish to pinkish lamellae without yellow tinges; and a white to cream stipe, which may turn to yellow-tan or presence of grey-tan tinges near the base with age.

Holotype:— NEW ZEALAND. Howick , Mangemangeroa Valley Walkway , remnant mature coastal broadleaf forest, fallen rooting small branch, 2 September 2015 leg. W. M. Daley ( PDD 107530 ); GenBank: KU 131674 ( P. R. Johnston and D. Park, unpublished, ITS) and MN 738601 ( J. A. Cooper, unpublished, LSU)

Additional collections examined:— NEW ZEALAND. Howick , Mangemangeroa Valley Walkway, remnant mature coastal broadleaf forest, on dead ‘white wood’ branch still attached to living tree, 1 April 2015 leg. W. M . Daley ( PDD 107527 , EMBL-Bank LR 812268 ); fallen rooting small branch, 29 March 2015 leg. W. M . Daley ( PDD 107529 ), sequences available in GenBank: KU131675 , MN738600 ; ibid small fallen branch, 23 November 2016 leg. et det. W. M . Daley as P. cf. minor ( PDD 106407 ) sequences available in Genbank: MN738650 , MN738575 .

Ecology and distribution:—Solitary or in small groups on rotting fallen deciduous wood.

Figures

FIGURE 3. Microscopic characteristics of Pluteus hubregtseorum. a: Basidiospores. b: Basidia. c: Pleurocystidia. d: Cheilocystidia, e: Pileipellis elements. f: Caulocystidia. Scale bar = 10 μm. Illustrated by Hana Ševčíková.

FIGURE 4. Macro- and microscopic characteristics. a–d: P. hubregtseorum f. hubregtseorum basidiomata (a–b MEL2341016, c MEL2341015, photos by J. & V. Hubregtse). d: Holotype of P. hubregtseorum f. hubregtseorum (HO 585031, photo by Ch. Fitzgerald). e–f: Holotype of P. hubregtseorum f. horakianus (PDD 107530, photo by W. M. Daley). g: P. hubregtseorum f. horakianus pileipellis elements, photo W. M. Daley. h: P. hubregtseorum f. hubregtseorum pleurocystidia (BRNM 825722), photo by H. Ševčíková. i: P. hubregtseorum f. hubregtseorum cheilocystidia (BRNM 825722), photo by H. Ševčíková.