Carmine colouration on R. aurora caused by sulphovanillin

[CloudedYellow]

Does anyone know if the carmine reaction to sulphovanillin on the stem of Russula aurora is species specific? Phillips says this feature 'distinguishes this species', which I take to mean that this doesn't happen in any other Russula sp. Fungi of Switzerland remarks on the feature but does not say if species specific and I cannot find any useful information on R. aurora on the internet. (I wonder why there is so little info. out there on aurora?)

Thanks

Richard

[Fungus Ken]

Geoffrey Kibby has very recently produced an updated synoptic key to the genus Russula in Great Britain.

For Russula aurora he says:

"Habitat: Fairly common early in the season, usually with Fagus, Castanea or Carpinus.

Notes: Often confused with other red species but easily distinguished by its SV reaction and 1/2 peeling cap. (R. lepidicolor is very similar but has adnate cuticle and pruinose cap.)"

Here "adnate cuticle" means the cap peels only at the very edge.

R. lepidicolor is "very uncommon to rare in the south of England, usually associated with beech, very few authenticated records."

Both have the red reaction with sulphovanillin (SV). However, R. aurora is clearly much the commoner. So if you find a red Russula with a red reaction to SV you almost certainly have Russula aurora. If the cap cuticle peels to half way, then you can be confident of your identification. If it doesn't peel you would need to do some more detective work because it might just be an old specimen.

Ken