Fluviphylax palikur: A new poeciliid from the rio Oiapoque basin, northernBrazil (Cyprinodontiformes : Cyprinodontoidei), with comments on miniaturization in Fluviphylax and other neotropical freshwater fishes

Fluviphylax palikur, new species, is described from the rio Taparabu, rio O iapoque basin, northern Brazil. It differs from all other species of the ge nus by the possession of numerous anal fin rays and vertebrae and by the sh ape of fourth and fifth ceratobranchials and second pharyngobranchial. Five synapomorphies shared by all species of Fluviphylax except F. palikur, in addition to characters supporting Fluviphylax monophyly, support a hypothes is of a sister-group relationship between the new species and a clade consi sting of the remaining species of the genus. Miniaturization and reductive morphological conditions in Fluviphylax are discussed in a phylogenetic con text. Miniaturization in Fluviphylax is hypothesized to correspond to a sin gle event, with reductive conditions originating at the base of the Fluviph ylax clade and in different intrageneric lineages. A list of Neotropical mi niature freshwater fish described in the last 10 years is presented.