AUTHOR=Qu Zhishuai , Pan Hongbo , Wang Congcong , Ma Honggang , Stoeck Thorsten , Hu Xiaozhong 

TITLE=Gastronautidae Deroux, 1994 and Trithigmostoma Jankowski, 1967: Evolutionary Links Among Cyrtophorian Ciliates (Protista, Ciliophora, and Phyllopharyngea)

JOURNAL=Frontiers in Marine Science

VOLUME=8

YEAR=2021

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.625644

DOI=10.3389/fmars.2021.625644

ISSN=2296-7745

ABSTRACT=<p>Studies on cyrtophorian ciliates (Cyrtophoria) have accumulated much knowledge on morphological taxonomy and molecular phylogeny, and the general classification and phylogenetic relationships of most families have thereby been revealed. However, the phylogenetic position of the family Gastronautidae <xref ref-type="bibr" rid="B10">Deroux, 1994</xref> remains uncertain. This is due to the presence of specialized characteristics (in particular a circumoral kinety in a closed circle), and most importantly, the lack of molecular data of this family. In addition, <italic>Trithigmostoma</italic><xref ref-type="bibr" rid="B21">Jankowski, 1967</xref> holds a special position among genera in Chilodonellidae Deroux, 1976 due to its divergent characteristics. In the present work, we studied a new gastronautid, <italic>Gastronauta paraloisi</italic> sp. n., and three populations of <italic>Trithigmostoma cucullulus</italic> (<xref ref-type="bibr" rid="B28">Müller, 1786</xref>) <xref ref-type="bibr" rid="B21">Jankowski, 1967</xref>, using integrative methods. Species identifications were confirmed by morphological research. We also obtained SSU rDNA sequences, which included the first available sequence of Gastronautidae. The following SSU rDNA-inferred phylogenetic analyses showed that the establishment of the family Gastronautidae is necessary, and Gastronautidae and <italic>Trithigmostoma</italic> may represent intermediate evolutionary links in the order Chlamydodontida.</p>