Oonops domesticus is a tiny spider (males about 1.5 mm, females 2 mm) from Western Europe

Western Europe

Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

 to Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

. It is of a bleak light red, with a reddish to whitish abdomen

Abdomen

In vertebrates such as mammals the abdomen constitutes the part of the body between the thorax and pelvis. The region enclosed by the abdomen is termed the abdominal cavity...

. It is found only in buildings, where it builds a retreat in corners and between old paper. It hunts at night, probably with booklice

Psocoptera

Psocoptera are an order of insects that are commonly known as booklice, barklice or barkflies. They first appeared in the Permian period, 295–248 million years ago. They are often regarded as the most primitive of the hemipteroids. Their name originates from the Greek word psokos meaning...

 their common prey. The translucent flat egg sac contains only two eggs.

It is very similar to the closely related O. pulcher

Oonops pulcher

Oonops pulcher is a tiny spider . Its six eyes are located closely together, giving the impression of only one eye...

, but has five tibial spine pairs instead of four. O. pulcher is found outdoors.