EARLY CRETACEOUS NON-MARINE OSTRACODA FROM THE NORTH FALKLAND BASIN, SOUTH ATLANTIC

Twenty-seven species of well-preserved and abundant Early Cretaceous non-marine ostracod crustaceans were recovered from the North Falkland Basin. The assemblage is unusually diverse for a non-marine palaeoenvironment and is sourced from cuttings samples collected during 2011 drilling of wells by Desire and Rockhopper Exploration, in the northern and southern areas of the basin. Ostracoda are entirely undocumented in published accounts from this basin, and all but one species appear to be new to science. For the new taxa, one new family (Alloiocyprideidae; type genus Hourcqia) is proposed and includes Hourcqia woodi sp. nov. Four new genera are erected: Falklandicypris gen. nov.; type species F.petrasaltata sp. nov., Gangamoncythere gen. nov.; type species G.colini sp. nov., Paraplesiocypridea gen. nov.; type species P.alloios sp. nov., and Musacchiocythere gen nov.; type species M.sarunata (Musacchio, ). Nine other species are described as new and are Falklandicypris desiderata, Clinocypris epacrus, Cypria poietes, Ilhasina? leiodermatus, Looneyellopsis tuberculatus, Theriosynoecum petasmathylacus, Theriosynoecum ballentae, Timiriasevia fluitans, and Vecticypris samesi. The remainder are left in open nomenclature due to paucity of material. The ostracod assemblage is largely restricted to the southern part of the basin (wells 25/5-1 and 26/6-1). In the northern part of the basin only four species, dominated by Vecticypris samesi, are present and with one possible exception are restricted there. There appears to have been little or no interchange of species suggesting that a barrier probably existed between the northern and southern regions. The more diverse southern assemblage indicates that more favourable conditions existed to the south. Stratigraphically, a distinct change in faunal composition recorded in both southern wells is likely to be an isochronous event correlatable across the southern area, and of an age no younger than Hauterivian.