COLLEMBOLA > PODUROMORPHA > ONYCHIUROIDEA > Onychiuridae

I guess that I need to start by saying that this is a somewhat tentative suggestion for the individuals seen in the photos below. A couple of other species were suggested, but dismissed due to either their general appearance, size or preferred habitat. 

If the genus is correct, the safe option is to record as Protaphorura armata 'group' but, although there are three currently recognised species on the British List, only two realistically need to be considered; Protaphorura armata and Protaphorura aurantiaca. Both are described as being common and widespread, and both occur in similar habitats. The distinguishing feature though, is that when observed live, Protaphorura armata is pure white, whereas Protaphorura aurantiaca is normally yellow (fades to white if collected and preserved).

They grow to about 2.5mm, but I would say the ones I saw were a bit smaller, probably under 2mm. Most of the features required to reliably confirm identity can only be seen under a microscope, but they do have two tiny anal spines, which I can just make out in the last photo when enlarged.

The species is typically found in soil, amongst leaf-litter, under stones or on rotting wood. The individuals that I found were under loose bark on an old fallen oak or beech tree. I hadn't even seen them at first, but fortunately there were a couple of really small saproxylic beetles that I'd spotted, and it was only when I started focusing on them that I realised that there were also some tiny sprigtails and even smaller, virtually pin-head sized, mites there as well.