The paleoecological significance of ovoidites

Ovaraoidites is an ovoid zygospore or aplanospore of the Zygnemataceae which is found in sediments of Cretaceous to Holocene age. Spores typically exhibit a prominent line of dehis-cence that allows them to split in half lengthwise. The variety of sizes, shapes, and sculpturing suggests that several natural species may be included within Ovoidites. Studies of sediment cores from marine, brackish, and freshwater sequences beneath islands in Florida Bay and at the mouth of the Harney River in Everglades National Park demonstrate the close association which the Spores have with freshwater peats and related pollen assemblages. Palynological study of freshwater peats from the Okefenokee Swamp in Georgia shows additionally that Ovoidites occurs preferentially with open-water marsh peat and pollen assemblages. The spores typically are not found in tree- or shrub-dominated areas, and, therefore, are not associated with tree and shrub peats. The apparently narrow range of habitat preferences which the algae display suggests that Ovoidites may be a valuable indicator of ancient freshwater coal deposits.