Ligidium hypnorum is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of woodlouse

Woodlouse

A woodlouse is a crustacean with a rigid, segmented, long exoskeleton and fourteen jointed limbs...

 found across 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...

 and western Asia. It is a fast-moving, active species which rarely grows longer than 9 millimetre (0.354330708661417 in). It is dark and shiny, and is similar in appearance to the common species Philoscia muscorum

Philoscia muscorum

Philoscia muscorum, the common striped woodlouse or fast woodlouse, is a common European woodlouse. It is found from the British Isles and southern Scandinavia east to Ukraine and south to Greece. It has also spread to Washington and many states in New England, as well as Nova Scotia.-Description:P...

, and also the rarer Oritoniscus flavus. In Great Britain

Great Britain

Great Britain or Britain is an island situated to the northwest of Continental Europe. It is the ninth largest island in the world, and the largest European island, as well as the largest of the British Isles...

, it was first discovered at Copthorne Common, Surrey

Surrey

Surrey is a county in the South East of England and is one of the Home Counties. The county borders Greater London, Kent, East Sussex, West Sussex, Hampshire and Berkshire. The historic county town is Guildford. Surrey County Council sits at Kingston upon Thames, although this has been part of...

 in 1873, and the majority of later records are also from South East England

South East England

South East England is one of the nine official regions of England, designated in 1994 and adopted for statistical purposes in 1999. It consists of Berkshire, Buckinghamshire, East Sussex, Hampshire, Isle of Wight, Kent, Oxfordshire, Surrey and West Sussex...

. It is considered a good indicator species

Indicator species

An indicator species is any biological species that defines a trait or characteristic of the environment. For example, a species may delineate an ecoregion or indicate an environmental condition such as a disease outbreak, pollution, species competition or climate change...

 for ancient woodland

Ancient woodland

Ancient woodland is a term used in the United Kingdom to refer specifically to woodland that has existed continuously since 1600 or before in England and Wales . Before those dates, planting of new woodland was uncommon, so a wood present in 1600 was likely to have developed naturally...

.