redescription of the genus Ploeotia Duj. (Euglenophyceae)

A colorless euglenoid was isolated from a sample of seawater collected from a New Jersey salt marsh in March 1984. This organism has been continuously maintained in the laboratory for the past three years. Though evidently belonging to a different species, this euglenoid bore remarkable similarities to Serpenomonas costata, previously described from the same sample. In ultrastructural features such as pellicle, flagellar apparatus, and feeding apparatus the organisms are nearly identical and there is little doubt that the two species belong to the same genus. Subsequent investigation revealed that the second species is Ploeotia vitrea Dujardin (1841), despite the fact that a feeding apparatus was neither mentioned nor illustrated by Dujardin. It has therefore become necessary to transfer S. costata to Ploeotia as a new combination, and to redescribe that genus to account for features that were not observed when the original description was made.