Our study of Apistonema pyrenigerum Pascher, a member of the haptophyte algal order Prymnesiales, collected from the Quivira National Wildlife Refuge, Stafford County, Kansas, includes data on its ecology, reproduction, and updated classification. Its habitat was saline and in laboratory cultures its growth indicated its ability to grow in a wide range of salinities, 6–85%. Previous reports for the alga are from Europe: Austria, Britain, Czech Republic, France, and Italy. Each cell possesses two parietal chloroplasts, although sometimes a single one is present. Each chloroplast contains a pyrenoid. The remainder of the cell consists of a large chrysolaminarin (leucosin) droplet and numerous small droplets. Zoospores are triflagellate, suggesting taxonomic placement in the family Prymnesiaceae.