The present study of the genus Doryaspis (Heterostraci, Pteraspidiformes), based on new material from the Wood Bay Formation (Lower Devonian) of Vestspitsbergen, includes a morphological description of a new species, Doryaspis arctica, sp. nov., the revision of the type species of the genus, Doryaspis nathorsti, and the description of its first complete caudal fin. From these new data, some morpho-functional considerations are outlined. A phylogenetic analysis, based on 30 morphological characters and performed to answer the question of the position of Doryaspis within the Pteraspidiformes, suggests that Doryaspis is most closely related to Drepanaspis.