title: A molecular and ultrastructural description of Spathidiopsis buddenbrocki and the phylogenetic position of the family Placidae (Ciliophora).
abstract: Spathidiopsis and Placus are the only two genera within the family Placidae. The family has been placed in the class Prostomatea and order Prorodontida because its members have somatic monokinetids with a radial transverse ribbon, a straight non-overlapping postciliary ribbon, and anteriorly directed non-overlapping kinetodesmal fibril, an apical cytostome lacking specialized oral cilia, a brosse, and toxicysts. To confirm the stability of this placement, ultrastructural morphology and small subunit rRNA gene sequences of Spathidiopsis socialis, Spathidiopsis buddenbrocki, and Placus striatus were determined. These data were combined with information from other ciliates, and phylogenetic trees were generated using maximum-likelihood and maximum-parsimony methods. The analyses confirmed the family Placidae to be a monophyletic group in the Prostomatea with the Placidae a sister group to a Cryptocaryon + Coleps + Prorodon clade.
authors.affiliation: Department of Biological Sciences, George Washington University, Washington, District of Columbia 20052, USA. biodl@gwu.edu
authors.forename: Diana L
authors.initials: DL
authors.lastname: Lipscomb
authors.forename: Brunella M
authors.initials: BM
authors.lastname: Bowditch
authors.forename: Gavin P
authors.initials: GP
authors.lastname: Riordan
mesh_terms: D016798:Ciliophora / Q000145:classification / Q000235:genetics* / Q000648:ultrastructure*; D016000:Cluster Analysis; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D015388:Organelles / Q000648:ultrastructure; D010802:Phylogeny; D016053:RNA, Protozoan / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D004275:DNA, Ribosomal; D016053:RNA, Protozoan; D012337:RNA, Ribosomal, 18S