Dolomedes plantarius was first described by arachnologist Carl Alexander Clerck in 1757 as Araneus plantarius but the genus was later reclassified as Dolomedes (Latreille, 1804). This species has also been described under the names Aranea viridata (Müller, 1776), Aranea plantarius (Olivier, 1789), Dolomedes riparius (Hahn, 1835), Dolomedes clerki (Simon, 1937; Renner, 1987). In the UK it is usually known as the the fen raft spider but the name great raft spider is also in common use.

D. plantarius is one of two species from the genus Dolomedes that occur in Europe. The other is the very similar the raft spider, Dolomedes fimbriatus. Although Europe has only two Dolomedes species, world-wide this is a large genus with at least 95 species. Although they are called raft spiders in Europe, they are often known as fishing spiders, dock spiders or wharf spiders in north America and as nursery web sipders in other regions.

The genus Dolomedes occurs all around the world and is particularly diverse in south east Asia. Many, but by no means all, of the species are often found in association with water and prey primarily on aquatic species. The striking lateral banding pattern seen in the European species occurs in many other species although by no means all species.

This patterning is also found in some other members of the same family, the Pisauridae, to which the genus Dolomedes belongs. In Europe there is only one other member of this family, the nursery web spider Pisaura mirabilis. Like all other members of its family, including the Dolomedes species, it constructs a tent-like nursery web in which to rear its young.

There are nine Dolomedes in North America. These include the pond dwelling D. triton, the bog dwelling D. striatus and four stream dwelling species, D. scriptus, D. vittatus, D. gertschi and D. holti. Two North American species, D. tenebrosus and D. okefinokensis, exhibit female giganticism and/or male dwarvism. The males of both species are less than half the size of the female. The ninth species is the terrestrial, tree-dwelling species D. albineus.