The genus Ploeotia represents a group of small, colorless, heterotrophic euglenids commonlyfound in shallow-water marine sediments. Species belonging to this genus have historicallybeen poorly described and studied. However, a Group I intron discovered within thesmall subunit ribosomal DNA gene of Ploeotia costata, makes P. costata the only euglenazoanknown to possess an actively splicing Group I intron. This intron contains conservedsecondary structures that indicate monophyly with introns found in Stramenopiles and Bangialesred algae. This project describes the internal and external morphology of a relatedspecies, Ploeotia pseudanisonema, using light and electron microscopy, and investigates thepossibility of a Group I intron within P. pseudanisonema. Using recently obtained SSU rRNAsequences, we also examine the phylogeny of Ploeotia, and comment on the relationship ofthe genus Keelungia to Ploeotia.
