This ruddy creature is my first ever Flea beetle but, just as with my recent new leafhopper, I haven’t been able to put a specific name to it. There are two very similar species, Sphaeroderma rubidum and Sphaeroderma testaceum, and, though the UK Beetles website maintains that ‘they are easily distinguished, with a little experience, by sight; the colour and shape being unique’, I don’t have the necessary experience.

The website explains:

Body strongly rounded, often almost circular, pronotum very strongly narrowed from the base and very finely punctured. 2.3-3.5 mm.  –  S. rubidum
Body less strongly rounded, slightly but distinctly elongate, the pronotum less strongly narrowed from the base and more strongly punctured, especially towards the basal margin. 2.5-4.2 mm.  –  S. testaceum

Without seeing the two beetles side by side or, perhaps, knowing in advance specifically what to look for, I find myself unable to identify the beetle I found.