The Bluefoot Bolete, Xerocomellus cisalpinus

 

It is difficult to be sure of these Xerocomellid species, and I do think you need to allow any blue colours to take time to appear. This one should be Xerocomellus cisalpinus as it is under broadleaved trees, but this fruiting body was lost too quickly for me to see if there was any eventual blueing at the foot of the stipe.

When a Xerocomellid is found it often shows a good clear yellow at the apex of the stipe, with extensive red markings, spots and streaks lower down the stipe. The pores may be a good yellow when young, but turn a yellow green when older, as shown here. If it is cisalpinus the fresh(?) pores themselves should blue reasonably quickly when bruised.

When you see the stem cut open, the first thing you may or may not notice is fairly extensive dark red or purplish red marks in the lower half of the flesh of the stipe. Any blueing may come slowly but should eventually be located extensively, throughout or at at the base of the stipe when it does appear. We did see that at Great Spelty Wood, Eastwell Farm near Stalisbury. Kibby also says that the outside of the stipe (at the base?) should blue up quite intensely within 5 minutes after bruising. 

The cap can crack quite intensely and should show a pinkish red underneath if it does so. We can see just a hint of it here. 

Supposedly under oak and some other broadleaf trees in the UK, only occasionally conifers. The opposite is said to be the case in other parts of Europe. In the Southeast of England cisalpinus appears to be the commonest and least fussy of the Xerocomellus chrysenteron sensu latu group of Xerocomellid species, found in parks and urban environments as well as mixed broadleaved woodlands..

Xerocomellus pruinatus, the Matt Bolete, should be distinguishable by a darker, often lumpy, pileus  with a yellow stipe perhaps with yellow mycelium, and limited red speckles. The flesh of the stipe is also golden yellow, blueing at the base, and apex. Under Beech and others.

Xerocomellus porosporus, the Sepia Bolete, is an "ugly" bolete, often showing a bit more of an overall greyish sepia. The stipe is sometimes mainly that dull greyish sepia, with a reddish ring above and then yellow at its final apex. When cut, the flesh turns reddish in the main, rather than any significant blueing. The pileus is often heavily cracked in appearance. Under Oak particularly.

Xerocomellus chrysenteron, the so-called Red-Cracking Bolete, should be lemon yellow at the apex, and then reddish over the rest of the stipe. When cut, the flesh should flush deep red below the cortex of the stipe with hardly any blueing. Typically and nominatively deterministically the pileus cracks red, but this can vary. Under conifers and only rarely under Beech.

The Lurid Bolete, Suillelus luridus

At the start of the KFC visit to Pilot's Wood and Meenfield Wood, which is a woodland complex near Badger's Mount and Polhill, and next to the Kent Wildlife Trust's chalk grassland reserve of Polhill Bank, the group quickly came across a very small patch of the quite colourful Lurid Bolete, Suillelus luridus, which I hadn't seen before and we didn't see again that day.   

Initially it looks quite a demure bolete with its overall matt brownish appearance, which I would have described as mainly khaki, with only subtle hints of apricot, in contrast to the book descriptions which rather emphasise the apricot. But looking a bit closer, you see the bright orange-reddish pore surface as well as the strong red reticulum over the yellowish stem and the intense blue when you cut the flesh or bruise the pores, together with a "purplish" base to the cut stem, and the overall impression is of a rather garish bolete! In these specimens the colour of the caps is quite matt, but still shows the apricot tinges of the published descriptions.

However, I failed, critically, to pick up the red colour in the line above the pores, this was clearly present but looked blue to me, but no-one else mentioned it, and the decision was very clear - luridus it was. This is a close-up of the cut surfaces. The patch at the base looked more orange to me rather than purple:

This is a close-up from the first photo above, showing the apricot colour of the stipe as well as the tinges in the pileus, what I think is the very strong, prominent reticulation with somewhat elongated meshes, and the deep and very rapid blueing of the pores and flesh.

In the UK it is said to have a preference for calcareous soils and to associate with Beech particularly, Oak and Limes, sometimes conifers. In mountainous regions it has been found in the presence of Mountain Avens. 

It should have had a pleasant fruity odour, although I didn't check. It is very variable, with named red and yellow varieties, and seems well spread throughout the UK, although not quite so well represented in Scotland, Wales and Ireland.

I had another look the following day at the same stand, and was able to separate the pore layer from the flesh above to reveal the base of the cap flesh from below and the thin layer of red (Bataille's line) that is characteristic of this species. In this specimen, not the best perhaps, it looked pink, with blue where bruising had occurred, and showed the "indentations" of the pore layer very clearly. The pore layer came away quite cleanly on the third attempt and this was definitely fun, as well as excellent confirmation of the announced identity!

I also looked more carefully for a better shot of the red reticulation over yellow, and here is the result, which I think is a little more convincing, although still not with as clearly elongated meshes as I was expecting.