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Pluteus atromarginatus (Singer) Kuhner - Blackedged Shield

Phylum: Basidiomycota - Class: Agaricomycetes - Order: Agaricales - Family: Pluteaceae

Pluteus atromarginatus - Blackedged Shield

The dark cap and black-edged pale gills are striking features of this wood-rotting mushroom, which is mainly found on decaying timber from pine trees. The specimen shown above is emerging from the gap between two old railway sleepers.

Distribution

A very rare find in Britain and Ireland, this saprophytic mushroom is also recorded in many parts of northern and central mainland Europe as well as in North America.

Blackedge Shield, Pluteus atromarginatus

Taxonomic history

This distinctive woodland mushroom was described in 1925 by German-born American mycologist Rolf Singer, who gave it the scientific name Pluteus cervinus var. atromarginatus. French mycologist Robert Kuhner (1903 - 1996) raised its status to species level in 1935, thereby establishing its scientific name as Pluteus atromarginatus.

Synonyms of Pluteus atromarginatus include Pluteus cervinus var. nigrofloccosus R. Schulz, Pluteus cervinus subsp. atromarginatus (Singer) K├╝hner, Pluteus tricuspidatus Velen., and Pluteus nigrofloccosus (R. Schulz) J. Favre.

Etymology

Pluteus, the genus name, comes from Latin and literally means a protective fence or screen - a shield for example! The specific epithet atromarginatus means 'with a black edge or margin' - a reference to the dark edge of the gills.

Identification guide

Cap of Pluteus atromarginatus

Cap

4 to 7cm across; initially convex, developing a slight umbo while flattening; margin remaining downcurved; dark brown to almost black, with adpressed radial fibrils; centre sometimes finely scaly.

Gills of Pluteus atromarginatus

Gills

Free; crowded; white with black or dark brown edges; gill faces turning pink as the spores mature.

Stem

5 to 12 cm long and 0.5 to 1cm diameter, often with a slightly swollen base; smooth white surface, sometimes with dark brown or black longitudinal fibres; no stem ring.

Spores of PLuteus atromarginatus

Spores

Broadly ellipsoidal or subspherical, smooth, 6-8 x 4-5µm.

Spore print

Pink.

 

Cheilocystidia of Pluteus atromarginatus

Pleurocystidia

PLeurocystidia on the gill faces are lageniform, typically 80 x 20µm, and project well beyond the basidia; as they mature they become ornamented with two, three or sometimes four apical 'horns'.

Show larger image

 

Odour/taste

Not distinctive.

Habitat & Ecological role

In common with other shield mushrooms, this is a wood-rotting (saprobic) fungus, but this species is unusual in being restricted to softwoods (timber of coniferous trees). Blackedge Shields tend to be either solitary or at best occuring in very small groups.

Season

Fruiting from early summer to late autumn.

Similar species

Pluteus cervinus has a smooth, paler brown or fawn cap and lacks the dark edge to its gills.

Culinary Notes

The Blackedge Shield is reported to be an edible mushroom, but in view of its rarity this mushroom should not be gathered for eating.

Reference Sources

Fascinated by Fungi, Pat O'Reilly 2016.

Singer, R. (1956). Contributions Towards a Monograph of the Genus Pluteus. Trans. Br. Mycol. Soc. 39(2): 145-232.

Orton, P.D. (1986). British Fungus Flora: Agarics and Boleti. Vol 4. Pluteaceae: Pluteus & Volvariella. Royal Botanic Garden: Edinburgh, Scotland.

Funga Nordica: 2nd edition 2012. Edited by Knudsen, H. & Vesterholt, J. ISBN 9788798396130

BMS List of English Names for Fungi

Dictionary of the Fungi; Paul M. Kirk, Paul F. Cannon, David W. Minter and J. A. Stalpers; CABI, 2008

Taxonomic history and synonym information on these pages is drawn from many sources but in particular from the British Mycological Society's GB Checklist of Fungi and (for basidiomycetes) on Kew's Checklist of the British & Irish Basidiomycota.

Acknowledgements

This page includes pictures kindly contributed by David Kelly.

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