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Insights into the phylogeny of three systematically controversial subfamilies of urostylid ciliates based on rDNA
Author(s) -
Chen Xumiao,
Li Ju,
Xu Kuidong
Publication year - 2021
Publication title -
zoologica scripta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.204
H-Index - 64
eISSN - 1463-6409
pISSN - 0300-3256
DOI - 10.1111/zsc.12473
Subject(s) - biology , monophyly , phylogenetic tree , paraphyly , subfamily , phylogenetics , evolutionary biology , genus , taxon , zoology , genetics , ecology , clade , gene
The family Pseudokeronopsidae Borror & Wicklow, 1983 has an extensive history of iterative revisions regarding phylogenetic relationships of its members and some related taxa from the order Urostylida. The accumulation of morphological and multigene data has provided the opportunity to gain a more comprehensive understanding of their systematic and evolutionary relationship. We conducted phylogenetic analyses of multiple molecular markers and predicted secondary structures of SSU rRNA and ITS regions by adding 14 new sequences. The results demonstrate that: (1) all the present phylogenetic analyses support the transfer of the subfamily Thigmokeronopsinae from the family Pseudokeronopsidae to the family Urostylidae; (2) the monophyly of two subfamilies Pseudokeronopsinae and Nothoholostichinae is substantiated with high support values of the SSU rDNA, LSU rDNA and the concatenated rDNA loci; (3) the monophyly of Pseudokeronopsidae is substantiated of the LSU rDNA only, and the AU tests do not reject the possibilities of Anteholosticha pulchra in this family; (4) phylogenetic trees based on the ITS region do not support the monophylies of the Pseudokeronopsidae and Nothoholostichinae, but the AU tests do not reject their possibilities; and (5) even though Pseudokeronopsis is morphologically well‐defined, it is very likely a paraphyletic genus in which both Antiokeronopsis and Uroleptopsis could be included. Moreover, this study reveals that the V2 and V4 regions of the SSU rRNA molecule are rather conserved at genus level and could be used to distinguish different subfamilies and families. Although they are less stable than the Watson–Crick complementarities, the GU appositions often occur in the ITS transcripts, which are much more variable at genus level than the V2 and V4 regions of the SSU rRNA molecule.