title: Small subunit rRNA phylogenies show that the class nassophorea is not monophyletic (Phylum Ciliophora).
abstract: The hypostome ciliates have been generally classified into two classes, Phyllopharyngea and Nassophorea. The status of Nassophorea and its relationship with Phyllopharyngea is one of the most controversial issues in ciliate systematics. Here we focus on the phylogenetic interrelationships of Nassophorea and Phyllopharyngea based on small subunit ribosomal RNA gene sequences. The three nassophorean subgroups, synhymeniids, microthoracids, and nassulids, each emerged as monophyletic, with synhymeniids as a sister group of Phyllopharyngea, and microthoracids as a sister of the synhymeniids+Phyllopharyngea clade in all phylogenies. The exact placement of the nassulids, however, remains uncertain. Following a detailed analysis of phenotypic characters, we hypothesize that: (1) the Phyllopharyngea could have evolved from synhymeniids, with the further development of their subkinetal microtubules as one of the major events; and (2) the development of monokinetid structures, as well as the reduction and specialization of the cyrtos and cortex, might have occurred during the diversifications of the microthoracids, synhymeniids, and Phyllopharyngea from a common ancestor. Expanding the class Phyllopharyngea to include the synhymeniids as a subclass, and designating a new subclass Subkinetalia n. subcl. for the group comprising cyrtophorians, chonotrichians, rhynchodians, and suctorians, are proposed.
authors: Department of Zoology, Natural History Museum, London SW7 5BD, United Kingdom. jgong@126.com
authors: Jun
authors: J
authors: Gong
authors: Thorsten
authors: T
authors: Stoeck
authors: Zhenzhen
authors: Z
authors: Yi
authors: Miao
authors: M
authors: Miao
authors: Qianqian
authors: Q
authors: Zhang
authors: David McL
authors: DM
authors: Roberts
authors: Alan
authors: A
authors: Warren
authors: Weibo
authors: W
authors: Song
mesh_terms: D000818:Animals; D016798:Ciliophora / Q000145:classification / Q000235:genetics; D019143:Evolution, Molecular; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016053:RNA, Protozoan / Q000032:analysis / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D016053:RNA, Protozoan; D012337:RNA, Ribosomal, 18S