Range expansion of golden crayfish, Orconectes luteus, in the Mississippi River

Golden crayfish (Orconectes luteus) specimens were collected in the Mississ ippi River at Grand Tower, Jackson County, Illinois in September and Octobe r 1999. This locality is the most eastern on record for the species and the most southern in Illinois. The high stream order habitat from which these crayfish were collected is generally not consistent habitat compared with p referred smaller order stream habitats used in other parts of the species' range. Previous collections of O. placidus from the Mississippi River may i n fact be O. luteus.