Molecular Phylogenetic Lineage of Plagiopogon and Askenasia(Protozoa, Ciliophora) Revealed by Their Gene Sequences  

作　　者：LIU An YI Zhenzhen LIN Xiaofeng HU Xiaozhong Saleh A.AL-FARRAJ Khaled A.S.AL-RASHEID 

机构地区：[1]Laboratory of Protozoology, Institute of Evolution & Marine Biodiversity, Ocean University of China [2]Laboratory of Protozoology, School of Life Science, South China Normal University [3]Zoology Department, College of Science, King Saud University

出　　处：《Journal of Ocean University of China》2015年第4期724-730,共7页中国海洋大学学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.31222050,41376141,3112041,and 31471973);the international research projects from King Saud University(Nos.RGP-VPP-083,IRG14-22)

摘　　要：Prostomates and haptorians are two basal groups of ciliates with limited morphological characteristics available for tax- onomy. Morphologically, the structures used to identify prostomates and haptorians are similar or even identical, which generate heavy taxonomic and phylogenetic confusion. In present work, phylogenetic positions lineage of two rare genera, Plagiopogon and Askenasia, were investigated. Three genes including small subunit ribosomal RNA gene （hereafter SSU rDNA）, internal transcribed spacer region （ITS region）, and large subunit ribosomal RNA gene （LSU rDNA） were analyzed, 10 new sequences five species each. Our findings included 1） class Prostomatea and order Haptorida are multiphyletic; 2） it may not be appropriate to place order Cyclotriehiida in subclass Haptoria, and the systematic lineage of order Cyclotrichiida needs to be verified further; 3） genus Plagio- pogon branches consistently within a clade covering most prostomes and is basal of clade Colepidae, implying its close lineage to Prostomatea; and 4） Askenasia is phylogenetically distant from the subclass Haptoria but close to classes Prostomatea, Plagiopylea and Oligohymenophorea. We supposed that the toxicyst of Askenasia may be close to taxa of prostomes instead of haptorians, and the dorsal brush is a more typical morphological characteristics of haptorians than toxicysts.Prostomates and haptorians are two basal groups of ciliates with limited morphological characteristics available for taxonomy. Morphologically, the structures used to identify prostomates and haptorians are similar or even identical, which generate heavy taxonomic and phylogenetic confusion. In present work, phylogenetic positions lineage of two rare genera, Plagiopogon and Askenasia, were investigated. Three genes including small subunit ribosomal RNA gene(hereafter SSU r DNA), internal transcribed spacer region(ITS region), and large subunit ribosomal RNA gene(LSU r DNA) were analyzed, 10 new sequences five species each. Our findings included 1) class Prostomatea and order Haptorida are multiphyletic; 2) it may not be appropriate to place order Cyclotrichiida in subclass Haptoria, and the systematic lineage of order Cyclotrichiida needs to be verified further; 3) genus Plagiopogon branches consistently within a clade covering most prostomes and is basal of clade Colepidae, implying its close lineage to Prostomatea; and 4) Askenasia is phylogenetically distant from the subclass Haptoria but close to classes Prostomatea, Plagiopylea and Oligohymenophorea. We supposed that the toxicyst of Askenasia may be close to taxa of prostomes instead of haptorians, and the dorsal brush is a more typical morphological characteristics of haptorians than toxicysts.

关 键 词：Plagiopogon Askenasia multi-gene phylogeny SSU rDNA ITS region LSU rDNA 

分 类 号：Q78[生物学—分子生物学]