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Phylogenetic analyses of ciliated protozoa have been increasingly relied on multigene information, which was revealed to provide more robust interpretations than single-gene information. Previous studies showed that Amphisiellidae was an extremely divergent group within the order Stichotrichida, with species widely dispersed throughout the stichotrichid assemblage, while Trachelostylidae, excluding gonostomatid species, is a monophyletic group within the order Sporadotrichida. In the present study, we provide 38 new sequences of SSU-rDNA, ITS1-5.8S-ITS2 and LSU-rDNA genes to infer phylogenetic relationships among all taxa available in Amphisiellidae and Trachelostylidae. The results indicate that: (1) Amphisiellidae is polyphyletic, with Amphisiella , Hemiamphisiella , Orthoamphisiella , Uroleptoides , and Urospinula distributing in different clades; (2) Amphisiella is separated into two clades in phylogenetic trees, corroborated by difference in cortical granule distribution. Thus, cortical granule pattern and distribution may be strong diagnostic features to divide Amphisiella species into two subgenera; (3) the monophyly of Trachelostylidae sensu Berger (2008) is strongly supported, suggesting it is a well-defined family; (4) Gonostomatidae is confirmed to be a valid family. [ABSTRACT FROM AUTHOR]

Highlights: [•] 36 new sequences for three genes are characterized from 20 species (12 genera) in the core group of Urostyloidea. [•] More well-supported and reliable nodes are detected in the concatenated topologies. [•] Multi-gene phylogenies and morphological features are discussed to improve the understanding of the evolution of urostyloids. [•] A new genus Arcuseries (type A. petzi) is established to contain three distinctly deviating Anteholosticha species. [Copyright &y& Elsevier]

Abstract: Although euplotida ciliates are widely used as model organisms in multiple fields of biology, details of their phylogenetic relationships remain unresolved despite a rich history of investigation with small subunit (SSU) rDNA sequences and other characters. Here, six genera in Diophrys-like complex and three other euplotid genera are sampled for SSU-rDNA, ITS1-5.8S-ITS2 and LSU-rDNA, and their phylogenies were inferred with unconstrained and constrained analyses. In general, the concatenated analyses infer more reliable, less ambiguous phylogenies with higher node support values. The following conclusions can be made: (1) four well-supported clades are consistently detected in the family Uronychiidae, forming into two subgroups, which challenge the traditional arrangement based on morphological similarities; (2) the subfamily Diophryinae is paraphyletic; (3) the monophyly of Paradiophrys and the establishment of Apodiophrys and Diophryopsis is fully supported by concatenated data; (4) Apodiophrys and Paradiophrys form independent lineages, at the subfamily level, from other Diophrys-like genera; and (5) the highly specialized Pseudodiophrys nests within Diophrys. [Copyright &y& Elsevier]

The Anteholosticha–Holosticha complex is an extremely divergent group within the urostylids, especially because the genus characterization lacks suitable synapomorphies. Previous studies have shown that morphological classification of species within this group often conflicts with SSU-rDNA data, that is this complex is not recovered as a monophyletic group and Anteholosticha spp. are widely dispersed throughout the urostylid assemblage in SSU-rDNA trees. In this study, we provided 38 new sequences (including the type species of Anteholosticha ) of SSU-rDNA, ITS1-5.8S-ITS2 and LSU-rDNA genes to infer molecular phylogenies of all available taxa in the Anteholosticha – Holosticha complex. The results show that: (1) Holosticha is monophyletic in all trees, suggesting it is a well-defined genus; (2) Anteholosticha is polyphyletic and distinctly separated from Holosticha in all single-gene based and concatenated phylogenies; (3) the monophyly of Arcuseries , a recently established genus split from Anteholosticha , is strongly supported by all molecular data; (4) Anteholosticha multicirrata , Anteholosticha manca , Anteholosticha paramanca and Bakuella subtropica may share a most recent common ancestor; (5) multi-gene analyses receive higher support values than the single-gene analyses. [ABSTRACT FROM AUTHOR]