Re-evaluation of the phylogenetic position of the genus Dexiotrichides (Protozoa, Ciliophora, Scuticociliatida) inferred from stomatogenetic and molecular information for Dexiotrichides pangi  

作　　者：SONG Weibo Alan WARREN David ROBERTS SHANG Huimin MA Hongwei Norbert WILBERT MIAO Miao YI Zhenzhen 

机构地区：[1]Laboratory of Protozoology, MRL, Ocean University of China, Qingdao 266003, China [2]Department of Zoology, Natural History of Museum, Cromwell Road, London, SW7 5BD, UK [3]Zoologisches Institut, Universitaet Bonn, 53115 Bonn, Germany

出　　处：《Progress in Natural Science:Materials International》2005年第8期700-707,共8页自然科学进展·国际材料（英文版）

基　　金：SupportedbyNationalNaturalScienceFoundationofChina(GrantNo.40206021),aRoyalSocietyjointprojects(GrantNo.Q822)awardtoAWandWSandaDFGvisitinggrantawardtoNWandWS

摘　　要：The divisional process and systematic position of the marine scuticociliate Dexiotrichides pangi are studied. Based on both stomatogenetic data and 18S rDNA gene sequences, the phylogeny and morphogenetic characteristics of this taxon, and of other related genera, are analyzed and discussed. Both the divisionary events and the molecular biological data indicate that this species/genus, together with certain other genera in the Dexiotricha-complex, occupies an intermediate position between the tetrahymenids and the “typical” scuticociliate, which suggests that the Dexiotricha-like taxa should be excluded from the “true” scuticociliates. As a further contribution, the process of stomatogenesis in D. pangi can be summarized as follows: (1) The oral primordia in the opisthe are formed only by the proliferation of basal bodies in the scutica field, which subsequently develop into three membranelles, while the new paroral membrane seems to be generated by the sub-anterior portion of somatic kinety 1 (the 1st postoral intercalary kinety). The latter character exhibits a mode similar to Tetrahymena. (2) In the proter the parental membranelles are retained and remain unchanged throughout the entire division process; only the old paroral membrane is disassembled and differentiated into the anlage, which then gives rise to the new paroral membrane and the scutica of the proter. The 18S rRNA gene sequence reported here is the first one for a ciliate in the Dexiotricha-complex.The divisional process and systematic position of the marine scuticociliate Dexiotrichides pangi are studied. Based on both stomatogenetic data and 18S rDNA gene sequences, the phylogeny and morphogenetic characteristics of this taxon, and of other related genera, are analyzed and discussed. Both the divisionary events and the molecular biological data indicate that this species/genus, together with certain other genera in the Dexiotricha-complex, occupies an intermediate position between the tetrahymenids and the “typical” scuticociliate, which suggests that the Dexiotricha-like taxa should be excluded from the “true” scuticociliates. As a further contribution, the process of stomatogenesis in D. pangi can be summarized as follows： （1） The oral primordia in the opisthe are formed only by the proliferation of basal bodies in the scutica field, which subsequently develop into three membranelles, while the new paroral membrane seems to be generated by the sub-anterior portion of somatic kinety 1 （the 1st postoral intercalary kinety）. The latter character exhibits a mode similar to Tetrahymena. （2） In the proter the parental membranelles are retained and remain unchanged throughout the entire division process; only the old paroral membrane is disassembled and differentiated into the anlage, which then gives rise to the new paroral membrane and the scutica of the proter. The 18S rRNA gene sequence reported here is the first one for a ciliate in the Dexiotricha-complex.

关 键 词：marine ciliate systematic position stomatogenesis 18S rRNA gene sequences Dexiotrichides pangi 

分 类 号：Q949[生物学—植物学]