Arrhenia umbratilis

Bog shadow

Names

Scientific: Arrhenia umbratilis

English: Bog shadow

Description

First authenticated record for Britain, Uist, 2012

This species displays typical Arrhenia characters of flat to funnel-shaped cap when mature, with pronounced decurrent gills.

Cap 30 mm, dark brown with a hint of purple and silky sheen when wet, edge down-turned at first, becoming flat with age, indent in centre. The stipe measures 30 x 5 mm, broader at the apex and slightly flattened, concolorous with centre of cap, silky. The gills are decurrent, buffy-brown with a dark edge. The number of gills reaching the stipe is 26.

Few members of this genus have cheilocystidia but this one does, and quite distinct. They are clavate, 32 x 7-5 microns (average) with a digitate appendage, mostly straight but some curved.

Voucher material was sent to Kew where the species was confirmed. The voucher material is now deposited in the Kew collection under accession number K(M) 180164.

The precise designation is Arrhenia umbratilis Fr. and not to be confused with Omphalina umbratilis.

Habitat

Found in mossy, moist habitat in acidic moorland conditions.

Footnote:

It turns out Arrhenius is named for the Swedish botanist Johan Arrhenius:

http://sv.wikipedia.org/wiki/Johan_Arrhenius Johan was the uncle of Svante Arrhenius, the famous chemist.

Distinct cheilocystidia

Please remember to submit your records to your local recording group or via the Scottish Fungi online recording form.

My thanks to Liz Holden for looking at my findings, agreeing with my conclusion, and suggesting I send it to Kew. To Alick Henrici and Martyn Ainsworth for confirming my findings and explaining the taxonomy.

Chris Johnson 2012 - http://www.hebridensis.org/