Triplumaria selenica Latteur, Tuffrau and Wespes, 1970 was redescribed from pyridinated silver carbonate-impregnated specimens. Triplumaria selenica has a slit of the vestibular opening extending posteriorly along the left side of the vestibulum. The wide C-shaped adoral polybrachykinety extends along the ventral side of the vestibular opening. The narrow perivestibular polybrachykinety extends laterally along the dorsal side of the vestibular opening from the right end of the adoral polybrachykinety and forms a loop extending posteriorly along the vestibular slit to join to the left end of the adoral polybrachykinety. The 18SSU rRNA gene of T. selenica as well as those of six other entodiniomorphid species, Raabena bella, Blepharocorys curvigula, Entodinium longinucleatum, Eudiplodinium rostratum, Metadinium medium, and Ostracodinium gracile was sequenced. The neighbor joining and maximum parsimony phylogenetic trees were constructed to discuss the evolution of entodiniomorphs. Our results will support and extend Wolska's hypothesis: the ancestral forms of blepharocorythids have evolved into ophryoscolecids and Cycloposthium species via the ancestor of Triplumaria. (C) 2010 Elsevier GmbH. All rights reserved.