Arthropods from the Lower Devonian Severnaya Zemlya Formation of October Revolution Island (Russia)

New arthropods from the Lower Devonian (lower Lochkovian) Severnaya Zemlya Formation, October Revolution Island, Russia, are described. Three groups of non-ostracode arthropods are present. Cheloniellids (Arachnata, Cheloniellida) are represented by Paraduslia talimaae n. gen., n. sp., Chasmataspids (Chelicerata, Chasmataspida) by Octoberaspis ushakovi n. gen., n. sp., and phyllocarids (Crustacea, Malacostraca, Phyllocarida) by Elymocaris urvantsevi n. sp. This fauna is significant as both cheloniellids and chasmataspids are extremely rare groups, while phyllocarids remain uncommon. Furthermore, this new chasmataspid material reveals two important morphological characters for the group: a genital appendage and metastoma. Both were previously considered autapomorphic for eurypterids; their presence in chasmataspids strongly suggests that Chasmataspida and Eurypterida are sister groups.