Neelipleona

The Neelipleona contain the smallest species out of all the springtails, apart from, perhaps, Mackenziella, as well as containing only around 45 species in six genera. They are all cryptic, lacking pigment or eyes. 
All the Neelidae have an unusual head down against the wind manner, with truncated antennae though long enough still to have contact with the soil surface. Hopkin famously once referred to Megalothorax minimus as 'a tiny old man hunched in a baggy coat'. It's an apt a description as any. 
 

Neelides species are the only members of the Neelipleona that have colour- variations on a bluish-grey pigment. The undescribed Australian Neelides species in the first two photos below have the brightest blue I've seen in the genus. They are always under 1mm big, though sharing a similar body shape to Neelus.

The Megalothorax genus and the few other closely related genera are the smallest in the Neelidae, no more than 0.6mm at their largest but usually much smaller. Like Neelus, they have no pigment, instead having the white and orange associated with cave and deep leaf litter/soil Collembola. On older specimens, like the Megalothorax minimus below, dorsal patterning can be seen.