Working through Harry Broughton’s old records it’s plain to see that Leicestershire and Rutland are far richer in ant species than modern records suggest. Whilst Formica fusca is the most common wood ant in Leicestershire, according to Harry, it wasn’t the only one. His records between 1970 and 2001 suggest Formica lemani has a stronghold in North West Leicestershire and there were even some BRC records up to 2017 suggesting this still may be the case.
These two species in particular are extremely similar and to the naked eye they are inseparable. Formica lemani, although present in the south west of England and Wales, has it’s main range in northern England and up through Scotland. In contrast, the Midlands and south of England represents the main distribution of Formica fusca. The further north we go, the less common fusca becomes and the more common lemani becomes and so interestingly, Leicestershire represents one of the few areas where both appear to reside together.
The species are separable only with a few key indicators under the microscope; Formica lemani possess erect hairs/bristles on the pronotum (this is the ‘shoulder and neck area’) and also a few long hairs on the middle femora whereas these characteristics are absent in Formica fusca. You can see this in the images below, with Formica fusca top and Formica lemani bottom.
And so when David Nicholls excitedly contacted me last week to say he thought he’d found Formica lemani in North West Leicestershire I too was excited (if a little disappointed not to have found it first!). He sent me the image below, taken under his stereo microscope which clearly shows those tell-tale erect hairs on the pronotum. (you have to look hard, but they are clearly there (look like little whites lines on this image – I zoomed the image even further when confirming the record – these ants are a bloody nightmare!).
I’ll head to the site to sample more and see how expansive the colony/colonies are, but that’s another one down and another growth spurt for the county list. Good work David!
Myrmecology VC55 