Taxonomic research on the early Cenomanian sponges from western Ukraine has been ongoing since the late 19th century. The taxonomic analysis conducted here supplements and extends the authors’ research results, presented in 2012 and 2013. A new portion of the studied material (over 500 specimens, mainly from the Petriv Quarry) revealed 26 species belonging to the order Sceptrulophora, 27 species to the order Lychniscosida, and two species of lithistid demosponges to the order Tetractinellida. Six new taxa are proposed: two sceptrulophorans – Tretodictyum petrivensis sp. nov. and Tretodictyum complicatus sp. nov.; four lychniscosidans – Khmilevskia papillata gen. et sp. nov., Brachiolites elongatus sp. nov., Plocoscyphia anastomosa sp. nov. and Ophrystoma olehii sp. nov. Apart from these, 15 hexactinellid species and one lithistid species, previously unknown from the Cretaceous of the study area, are described in detail. The early Cenomanian sponge fauna of western Ukraine consists almost exclusively of hexactinellid sponges and comprises a total of 56 species. This makes it the richest and taxonomically most diverse assemblage of hexactinellid sponges from the Cenomanian in the world. Microfacies and petrographic studies of the material, infilling the sponge skeletons and the surrounding rocks, suggest that the early Cenomanian sponge meadows were located in a deeper part of the shelf. This area was calm, but within reach of material, carried from the mainland (silt-sized quartz from the Ukrainian Land). In many respects, the habitat of these sponges resembles the conditions, prevailing today on the western Canadian continental shelf, where hexactinellid reefs (mounds) have been found.
