Acipenser is a genus of sturgeons, containing three species native to freshwater and estuarine systems of eastern North America and Europe. It is the type genus of the family Acipenseridae and the order Acipenseriformes.

Taxonomy

thumb|[[European sea sturgeon|Acipenser sturio is the type species of the genus]]

Prior to 2025, Acipenser contained almost all species in the Acipenseridae outside of Huso and the "shovelnose" sturgeons (Scaphirhynchus and Pseudoscaphirhynchus). However, such a placement is now known to be paraphyletic with respect to the other genera, and these species have since been split into Huso and Sinosturio. Acipenser in the strict sense (sensu stricto) has been redefined with only 3 species.

This is an ancient genus, with phylogenetic evidence suggesting that it is the most basal sturgeon genus, having diverged from other sturgeons during the Early Cretaceous period. Several fossil species known as far back as the Late Cretaceous, with the fossils of two species (A. praeparatorum and A. amnisinferos) known from mass mortality assemblages thought to immediately follow the Chicxulub impact, the beginning of the Cretaceous-Paleogene extinction event.' However, the classification of these fossil species is uncertain under the new taxonomy; for example, "Acipenser" praeparatorum may actually represent a more derived sturgeon related to the Huso-Pseudoscaphirhynchus lineage. are thought to be nomina dubia.

  • †Acipenser albertensis <small>Lambe, 1902</small> (Late Cretaceous of Alberta, Canada)
  • †Acipenser amnisinferos <small>Hilton & Grande, 2023</small> (Late Cretaceous of North Dakota, USA)
  • †Acipenser chilini <small>Nessov, 1983</small> (Early Paleocene of Kazakhstan)
  • ?†Acipenser cretaceous <small>Daimeries, 1892</small> (Late Cretaceous of Belgium; potentially a teleost)
  • †Acipenser eruciferus <small>Cope, 1876</small> (Late Cretaceous of Montana, USA)
  • †Acipenser gigantissimus <small>Nessov, 1997</small> (Late Cretaceous of Saratov, Russia)
  • †Acipenser lemoinei <small>(Priem, 1901)</small> (Early Eocene of France)
  • ?†Acipenser molassicus <small>Probst, 1882</small> (Miocene of Germany; potentially a chondrichthyan)
  • †Acipenser ornatus <small>Leidy, 1873</small> (Miocene of Virginia, USA)
  • †Acipenser parisiensis <small>Priem, 1908</small> (Early Oligocene of France)
  • †Acipenser praeparatorum <small>Hilton & Grande, 2023</small> (Late Cretaceous of North Dakota, USA)