Phylogenetic Relationships of the Subclass Peritrichia (Oligohymenophorea, Ciliophora) Inferred from Small Subunit rRNA Gene Sequences¹

Abstract

The phylogenetic relationships among peritrichs remain unresolved. In this study, the complete small subunit rRNA (SSrRNA) gene sequences of seven species (Epistylis galea, Campanella umbellaria, Carchesium polypinum, Zoothamnium arbuscula, Vaginicola crystallina, Ophrydium versatile, and Opercularia microdiscum) were determined. Trees were constructed using distance-matrix, maximum-likelihood and maximum-parsimony methods, all of which strongly supported the monophyly of the subclass Peritrichia. Within the peritrichs, 1) E. galea grouped with Opercularia microdiscum and Campanella umbellaria but not the other Epistylis species, which indicates that the genus Epistylis might not be monophyletic; 2) the topological position of Carchesium and Campanella suggested that Carchesium should be placed in the family Zoothamniidae, or be elevated to a higher taxonomic rank, and that Campanella should be independent of the family Epistylididae, and probably be given a new rank; and 3) Opisthonecta grouped strongly with Astylozoon, which suggested that Opisthonecta species were not the ancestors of the stalked peritrichs.

Phylogenomic analyses reveal subclass Scuticociliatia as the sister group of subclass Hymenostomatia within class Oligohymenophorea

“…3). Specifically, in studies based on SSU rRNA gene sequences, the subclass Hymenostomatia is most closely related to the Peritrichia (Li et al, 2006;Miao et al, 2004;Miao et al, 2001), whereas in the present study based on phylogenomic analyses Hymenostomatia is sister to Scuticociliatia, and Peniculia is sister to Peritrichia.…”

“…Nevertheless, phylogenetic analyses based on SSU rRNA gene sequences generally recover the Oligohymenophorea as a monophyletic group, albeit often with only moderate bootstrap support (Lynn, 2008;Miao et al, 2004). In the present study based on omics data, the monophyly of the class Oligohymenophorea was recovered with maximal support in both the ML and BI trees.…”

“…Phylogenetic analyses based on SSU rRNA gene sequences have usually revealed that the subclass Hymenostomatia is the most closely related to the Peritrichia (Li et al, 2006;Miao et al, 2004;Miao et al, 2001). However, the subclass Scuticociliatia was found to be more closely related to the Hymenostomatia than to either the Peniculia or the Peritrichia in analyses based on three concatenated rDNA gene sequences (Gao et al, 2013), casting further doubt on the reliability of SSU rRNA gene data alone for revealing phylogenetic relationships among the oligohymenophorean subclasses.…”

“…Several phylogenetic analyses derived from SSU rRNA gene sequences have subsequently placed the hymenostomes and peritrichs as sister lineages (Li et al, 2006;Miao et al, 2004;Miao et al, 2001), indicating that the subclass Hymenostomatia is most closely related to the subclass Peritrichia rather than Scuticociliatia. However, a more recent analysis based on three concatenated rDNA sequences revealed that Scuticociliatia is more closely related to Hymenostomatia than to either Peniculia or Peritrichia (Gao et al, 2013).…”

“…The phylum Ciliophora is divided into 12 classes of which the Oligohymenophorea is arguably the most diverse and is consistently recovered as a monophyletic group in molecular phylogenies (Miao et al, 2004;Miao et al, 2001;Sanchez-Silva et al, 2003;Struder-Kypke et al, 2000). The Oligohymenophorea has long attracted the attention of researchers for a variety of reasons, two of the main ones being: (1) the inclusion within this group of two model genera, namely…”