title: Molecular phylogeny and surface morphology of Colpodella edax (Alveolata): insights into the phagotrophic ancestry of apicomplexans.
abstract: The molecular phylogeny of colpodellids provides a framework for inferences about the earliest stages in apicomplexan evolution and the characteristics of the last common ancestor of apicomplexans and dinoflagellates. We extended this research by presenting phylogenetic analyses of small subunit rRNA gene sequences from Colpodella edax and three unidentified eukaryotes published from molecular phylogenetic surveys of anoxic environments. Phylogenetic analyses consistently showed C. edax and the environmental sequences nested within a colpodellid clade, which formed the sister group to (eu)apicomplexans. We also presented surface details of C. edax using scanning electron microscopy in order to supplement previous ultrastructural investigations of this species using transmission electron microscopy and to provide morphological context for interpreting environmental sequences. The microscopical data confirmed a sparse distribution of micropores, an amphiesma consisting of small polygonal alveoli, flagellar hairs on the anterior flagellum, and a rostrum molded by the underlying (open-sided) conoid. Three flagella were present in some individuals, a peculiar feature also found in the microgametes of some apicomplexans.
authors.affiliation: Canadian Institute for Advanced Research, Program in Evolutionary Biology, Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada. bleander@interchange.ubc.ca
authors.forename: Brian S
authors.initials: BS
authors.lastname: Leander
authors.forename: Olga N
authors.initials: ON
authors.lastname: Kuvardina
authors.forename: Vladimir V
authors.initials: VV
authors.lastname: Aleshin
authors.forename: Alexander P
authors.initials: AP
authors.lastname: Mylnikov
authors.forename: Patrick J
authors.initials: PJ
authors.lastname: Keeling
mesh_terms: D000818:Animals; D016782:Apicomplexa / Q000235:genetics* / Q000648:ultrastructure; D001483:Base Sequence; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D008855:Microscopy, Electron, Scanning; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016415:Sequence Alignment
chemical_list: D016054:DNA, Protozoan