Systematics of serpulid tubeworms (Annelida, Polychaeta) from Cretaceous and Cenozoic hydrocarbon-seep deposits in North America and Europe

Detailed taxonomic descriptions, including tube microstructural details, are provided for four serpulid polychaetes from Cretaceous to Miocene deep-water hydrocarbon-seep deposits, including one new species. Nogrobs? hydrocarbonicus sp. nov. from the Valanginian Bear Creek site in the Great Valley Group, California, USA, has a tube with spherulitic prismatic inner and outer layers and may be the first record of this genus from deep-water deposits. Propomatoceros sp. is recorded from the Valanginian Rocky Creek site in the Great Valley Group, California, USA, and has a similar tube microstructure to Nogrobs? hydrocarbonicus. From the Middle Eocene Humptulips Formation in western Washington, USA, we describe Hyalopomatus aff. biformis, which has a two-layered tube wall, consisting of a thin spherulitic prismatic outer layer and a thick inner layer with irregularly oriented prisms. Lastly, Protis sp. is described from a seep deposit in the late Miocene San Paolo Marls in northern Italy, which unfortunately lacks preserved tube microstructure. Comparative remarks on related fossil and extant species are provided. The state of preservation and tube microstructures of the studied serpulid species are similar to those found in shallow marine communities of similar age.