title: Molecular Phylogeny of Mobilid and Sessilid Ciliates Symbiotic in Eastern Pacific Limpets (Mollusca: Patellogastropoda).
abstract: The phylogenetic relationships of the ciliate subclass Peritrichia, composed of the orders Mobilida and Sessilida, have recently come under debate as morphological and molecular analyses have struck contrasting conclusions as to the monophyly of the group. We provide additional molecular data to assess the monophyly of the Peritrichia by sequencing the small subunit ribosomal RNA genes of two symbiotic peritrichs, Urceolaria korschelti and Scyphidia ubiquita, found inhabiting the mantle cavity of limpets. Although phylogenetic analyses indicated a nonmonophyletic Peritrichia, approximately unbiased tests revealed that the monophyletic hypothesis could not be rejected. With regard to the Mobilida, our analysis showed divergence within the family Trichodinidae related to host taxa-a molluscan clade and a fish clade. For the Sessilida, the family Scyphidiidae was sister to the Astylozoidae. In our sampling of U. korschelti and S. ubiquita, both species showed significant genetic divergence among geographically isolated, yet morphologically indistinguishable populations. We hypothesize that cryptic speciation has produced these morphologically identical species and argue that more extensive genomic analyses are required to fully assess the monophyly, biogeography, and ultimately biodiversity of the peritrichs.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada.
authors.forename: Nicholas A T
authors.initials: NA
authors.lastname: Irwin
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada.|Department of Integrative Biology, University of Guelph, Guelph, N1G 2W1, Ontario, Canada.
authors.forename: Denis H
authors.initials: DH
authors.lastname: Lynn
mesh_terms: D000818:Animals; D044822:Biodiversity; D016798:Ciliophora / Q000145:classification* / Q000166:cytology / Q000235:genetics*; D016054:DNA, Protozoan / Q000235:genetics; D049851:Gastropoda / Q000469:parasitology*; D020459:Genes, rRNA; D008969:Molecular Sequence Data; D016802:Oligohymenophorea / Q000145:classification; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D054679:Ribosome Subunits, Small / Q000235:genetics; D017422:Sequence Analysis, DNA
chemical_list: D016054:DNA, Protozoan; D012337:RNA, Ribosomal, 18S
keywords: Biogeography; Ciliophora; Peritrich; Scyphidia ubiquita; Urceolaria korschelti; cryptic speciation; monophyly