Girardia tigrina, known as the brown planarian or the immigrant triclad flatworm, is a species of dugesiid native to the Americas.

[3] Originally from the Americas, Girardia tigrina has become an invasive species in Europe and Japan.

Since being first recorded in France in 1925,[4] this species has been reported from many other European countries, including Germany,[5][6] Italy,[7] the Netherlands,[8] Romania,[9] and Wales.

[10] In North Wales, this species has displaced the native triclad species Polycelis nigra and Polycelis tenuis due to its superior exploitation of food.

[2] G. tigrina is a carnivorous species that feeds on invertebrates such as oligochaetes, isopods, chironomids, snails, caddisflies, and mayflies.