Oonopidae: Pink Prowlers

A medium sized family which includes spiders with six, four or two eyes, and even eyeless cave dwelling species. There are two British species of the genus Oonops, but also at least three other species introduced and now living in hot-houses. They are tiny pinkish spiders, up to 2 mm long. They have six eyes in a cluster, and are nocturnal wandering spiders that spend the day in a simple silk cell. They have a simple female genital opening and male palp. These spiders have a most peculiar way of moving, with a slow walk with front legs stretched out like feeling the ground, followed by a run at speed.

Under recorded
 Oonops domesticus, also called the Pink Prowler, is only found inside houses, but it does easily go unnoticed due to its nocturnal habits. Michael Roberts recommends getting up at 3 or 4 in the morning and checking the walls for the presence of this spider, adding 'By a strange coincidence my first sighting of O. domesticus in our present home was when illustrating the species, at 4 a.m., and it ran across the illustration!'. A more civilised alternative is to search for the outdoors species, O. pulcher under rocks and bark or in bird nests or dry leaf litter. O. pulcher is often associated to the webs of larger spiders, like Amaurobius and Tegenaria. There it acts as a scavenger, feeding on the discarder remains of their prey. A further indication of how under recorded these tiny spiders are, is this confession by William Bristowe:

 'three species which I had added to the British list - Oonops domesticus, Euophrys lanigera and Physocyclus simoni were subsequently found in the British Museum (Natural History)! May I be forgiven for disclosing this secret.'

Small brood
They hold the record of fewest eggs per brood, just two, which are laid in the mothers cell in a transparent egg sac.

UPDATE 20/09/16. Post now includes a photo of a Oonops (likely domesticus) that walked on my office wall while I was working, my first sighting of these spiders.