Caesar's Camp ants

Caesar's Camp ants

Observation - Caesar's Camp ants - UK and Ireland. Description: These ants were very active in and around an old tree stump. They were foraging up a tree and on a s

These ants were very active in and around an old tree stump. They were foraging up a tree and on a shrub just a few feet from the stump and the stump appeared to be their nest. At first I thought they must be Formica rufa but after subsequent visits leading up to yesterday I have been unable to locate any kind of mound anywhere within 50 meters of these ants. Some of the ants did appear to be moving wood material to the stump but under observation through a magnifying glass I believe there is an anterior notch on the clypeus leading me to believe these are actually Formica sanguinea. There were also some Formica fusca very close to the stump which appeared to be coexisting with the ants pictured, further leading me to believe these are Sanguinea. However, I also spotted some very small ants which I believe are Formicoxenus nitidulus and which I hope to upload some photos of soon. These I saw on the tree a few feet from the stump. As I have not seen any information about them cohabiting with F. sanguinea I am now uncertain about the identification.