The Distribution and Evolution of Terrestrial Nemertines

The occurrence of terrestrial nemertines on widely separated oceanic islands is described: there are three groups of species (in Australia, New Zealand and the Indopacific islands) and three separate species on Atlantic islands. Parallel evolution from separate marine ancestors is indicated. The evolutionary relationship between different species is established on secure morphological grounds, with particular reference to the genus Pantinonemertes which comprises marine, semi-terrestrial and fully terrestrial species. The distribution of terrestrial nemertines is discussed. Most species are extremely localised but a few have become widely dispersed, notably Argonemertes dendyi but also Geonemertes pelaensis and to a lesser extent Leptonemertes chalicophora. At least two of these widespread species are hermaphrodite.