The genus Cortinarius

[Steve]

Cortinarius
Hi,
We found a large troop of Cortinarius near a veteran Oak in Longshaw on Thursday. Usually I don’t bother trying to name Webcaps unless they are quite strikingly coloured or patterned. That’s because I analysed the data from the Sheffield region a few years ago, and there are almost as many recorders as species (well not quite).
However, this one was quite nice, with features like Telamonia, so I thought I’d have a go. The cap was conical when young with a white cortina. Colour was a lovely rusty brown, with paler rim, radially streaked and splitting a little. Cap up to 5 cm across. The cap flesh was whitish to pale brown. Gills chestnut, attachment adnate to free (!). Stem silvery streaked pale brown, rather tapering to the base, varying a lot in proportion from slender to chunky (like Spindleshank) – to 8 cm x 1.3 cm. Flesh in stem tinged brown, darker to base. There was no trace of stickiness in the mushroom, but the cap looked hygrophanous. Spores were typically 6-8 x 5-6. A basidium measured about 40 x 8, with a clamp. The gill edge was dismal, with a few marginal cells looking like basidioles. The cap cuticle was made up of irregular elongated cells, with no evidence of gelatinisation.
There’s no way I expect to get an ID for this, for reasons to be given in the next post, so I thought I'd introduce it as a general discussion topic . But if you know what it is....
Cheers,
Steve

[Steve]

Why I don't expect an ID!

Graph 1) The blue pie represents all our local Sheffield area fungi records excluding Cortinarius. From over 63,000 records just over 400 are Cortinarius (= 0.6%) and Webcaps are by far the biggest genus of toadstools in the UK and the world. (Data from Sorby Fungus Group to 2012, including FRDBI records for SW Yorks and Derbyshire to 2009). The Webcaps are either truly uncommon or much disregarded.

Graph 2) The multicoloured pie chart represents the proportion of records for each species of Webcap in the Sheffield area records. Most have less than 4 records, a large number have just 1 or 2. That’s over 100 years worth of records!

Graph 3) The histogram chart represents the number of records for each species (blue) and the number of recorders for that species (red). C. anomalus has 31 records and at least 15 recorders (it's a variable species so hardly a dead cert to put a name to). About 70 recorders are "anon" so there may be more individual recorders than shown. By and large most species are only ever reported once or a couple of times by a recorder.

The map shows the distribution of Webcaps in the Sheffield area (excluding Nottinghamshire and westernmost parts of the Peak District). I’ve found most of those within the city of Sheffield.

A big problem in identifying species is getting yout specimen to match a picture - most of the ones I find just don't fit. The coverage in many reference works isn't very comprehensive. Funga Nordica has an 118 page key (no pictures!) but Phillips and the Collins Guides give less than half the 420 or so species on the FRDBI list.
Roger Phillips: approx 115 illustrated
Collins: Courtecuisse and Duhem state that there 500-2,500 species (Britain and Europe) depending on the authority! – approx 115 illustrated
Collins, Sterry and Hughes: approx 70 illustrated
Collins, Buczacki: approx 125 illustrated
My slightly dated version of Mycokey has the following comment:
"Over 500 species in Northern Europe, 36 in Mycokey. The Mycokey species coverage is disastrous."

The general consensus seems to be that Cortinarius is the biggest genus of mushrooms in the UK, Europe and the world, very heterogeneous, with few strikingly characteristic features to unify the genus, and is the most difficult to identify to species. Also, that to identify species reliably you need to be a specialist using microscopy. In addition, Cortinarius is normally not possible to ID from a single toadstool – you need a whole range of specimens from young to mature. As well as all this, the taxonomy is in a state of flux.

A comment from the much-missed Wild About Britain website:
" “…Kew probably wouldn't be too happy if you start sending lots of Cortinarius in for identification … since they are far from worked out properly (taxonomically) and it takes a hell of a long time to try and key them out, only to give up in the end and send the reply back as 'Cortinarius sp.' [with maybe a comment about the sub-group to which it belongs] which the sender already knew it was in the first place !”

The map was produced from Ordnance Survey data using freeware provided by Adrian Middleton, downloadable from <a href="http://datmapr.jimdo.com/downloads/" rel="nofollow">datmapr.jimdo.com/downloads/</a>
The base map was provided by Museums Sheffield <a href="http://www.museums-sheffield.org.uk/" rel="nofollow">www.museums-sheffield.org.uk/</a>

Steve

[Steve]

Hi,
By sheer coincidence after posting this, I found a troop of about 20 Webcaps under Beech, in Deschampsia cespitosa at Longshaw on Wednesday. Altitude approx 1000 ft, acid moorland pasture. They were a striking golden yellow – I thought about Golden Bootleg at first. As I was able to collect samples of young and older specimens I reckoned I might have a stab at ID.
The cap was yellow-golden-brown, very sticky, up to 16 cm diameter, with velar remnants on the margin. Surface finely scaly, then cracking. The stem was dry, with irregular rings of brownish veil. It was around 10 x 2 cm, either slightly swollen, cylindrical or very slightly tapered at the base. The gills were pale brown, adnate to sinuate, quite crowded. The cortina was white.
Flesh was whitish, turning yellow with 10% KOH immediately.
Spores were 9.5-13 x 5-6. No cheilocystidia were noted, nor were basidia easily seen on the gill edge. The cap cuticle contained hyphae up to 12 wide, with large clamp connections.
I gave up on the keys as they seem to want you to taste the gluten – no thanks! Browsing through Fungi of Switzerland and Bon brought C. trivialis and C. triumphans up as possibilities. The spore size fitted Bon better than FOS. As C. triumphans is a species usually with Birch, I wonder if this is C. trivialis – but the colour matches C. triumphans as described in Bon “a beautiful yellow verging on fawn”, rather than C. trivialis which is “dull olive-ochre to dingy brown”.
Steve

[Leif]

From experience characteristics of C. trivialis include a very sticky cap (often dripping with slime), and a stem which sometimes has bands of slime, and bands of cracking. The colour seems okay. So appearance wise yours seems okay. I have not checked your microscopy.

[Steve]

Hi Leif,
Yes - I suppose it's more likely C. trivialis because it's not with Birch - and the weight of opinion in the literature seems to suggest that C trivialis is more or less specific for Birch. I'm pretty sure there was just Beech and Pine nearby - but I will check again on our next visit. I have plenty of dried material to carry on scrutinising. But it was a very striking yellow colour - much like Suillus grevillei - Larch Bolete.
Cortinarius is a truly formidable genus, and puts we humans firmly in our place in assuming we can put a name to everything on this incredible and misused planet!
Kind regards,
Steve

[Leif]

This is very useful:

http://www.basidiochecklist.info/Displa ... GBNum=2071

So the absence of betula is not significant.

[Leif]

I had a look in Cortinarius Flora Photographica, they state that for Cortinarius triumphans the cap is glutinous (always?) and the stem scaly as per your photos. They note a yellow colour chnage in the stem on exposure to KOH. They say it occurs with betula. I could email a photo or scan of the page if you want. I won't post online as that might infringe copyright. They give quite a bit of microscopy details. Visually your specimens are a good match, for what that is worth. Yours seem to lack a clavate stem, but some of their samples are more equal.

[Steve]

Hi Leif,
Many thanks for that and sorry for the tardy reply. Very busy with the NT on Longshaw at the moment. Yes the Checklist is good - some older books have it as specific for Betula.
I think this is another "on the balance of evidence" cases - I'll name it C. triumphans with the caveat that one is unlikely to make a very confident ID of species that you have never seen before and may not see again for many years. No way am I going to get the "jizz" of stuff like this.So it's a reasonably comfortable ID, somewhere around 7 on a scale of 1-10.
Cheers,
Steve

[Steve]

And I've just checked the records - we have this from Longshaw by one of our best local mycologists, Tony Lyon, from some time before 1987. It's one I entered from old sheets of paper kept by his students. Most of his records were lost when a computer was discarded, apparently. So it's good to confirm a very unsatisfactory record
Steve