Rugathodes bellicosum is a small theridiid

Theridiidae

Theridiidae is a large family of spiders, also known as the tangle-web spiders, cobweb spiders and comb-footed spiders. The diverse family includes over 2200 species in over 100 genera) of three-dimensional space-web-builders found throughout the world...

 spider that occurs in Europe

Europe

Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...

, including 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 usually found on high ground, but also occurs on coasts. They live under large stones.

In Czechoslovakia

Czechoslovakia

Czechoslovakia or Czecho-Slovakia was a sovereign state in Central Europe which existed from October 1918, when it declared its independence from the Austro-Hungarian Empire, until 1992...

, spiders at low altitude are only found in small caves. These specimens are not very pigmented. Other specimens that live in higher elevations live more in the open and are generally darker in color. The variation seems to be genetic rather than environmentally induced.