Expanded Phylogenetic Representation of Genera Opercularia and Epistylis Sheds Light on the Evolution and Higher‐Level Taxonomy of Peritrich Ciliates (Ciliophora: Peritrichia)

Abstract

We have generated 18S rRNA sequences for peritrichs collected in Brazil, including four Opercularia species, two different populations of Epistylis plicatilis (one epibiont and another free-living), and one additional Epistylis species. Our Opercularia species clustered with the previously available Opercularia microdiscum, corroborating the monophyly of this genus. The Epistylis sampled here clustered with previously sequenced species of this genus. The two populations of E. plicatilis collected in Brazil clustered closely together despite their different ecological contexts, whereas both were very divergent from the sample assigned to the same species previously sampled in China. If affirmed by additional morphological corroboration of species assignment, this observation would indicate that samples from different continents morphologically allocated in the same species may in fact belong to distant evolutionary lineages. More broadly, our results support the recognition of two major clades within Peritrichia. Given the robustness of their support, we suggest that these two clades should be formally recognized as orders, and propose the names Vorticellida and Operculariida to designate them. Furthermore, Epistylis species occurred in both orders, tending to occupy basal positions. This suggests that characters used to define this genus may be plesiomorphic for Peritrichia, so that Epistylis may in fact represent an assemblage of basal species retaining ancestral features.

Phylogenomics solves a long-standing evolutionary puzzle in the ciliate world: The subclass Peritrichia is monophyletic

“…Further analyses including more members of Peniculia will likely resolve the position of this taxon. Another very frequent relationship is that of the Hymenostomatia as sister taxon to the Sessilida (Li et al, 2008;Sun et al, 2011;Utz et al, 2010;Zhan et al, 2009). In contrast, our analyses show that Hymenostomatia is sister to Scuticociliatia, confirming the phylogenomic analyses of Feng et al (2015).…”

“…At the time, it was suggested that the taxon sampling might be inadequate. Even with increased taxon sampling, investigations have failed to unite the two lineages (Gong et al, 2006(Gong et al, , 2010Li et al, 2008;Utz and Eizirik, 2007;Utz et al, 2010). Even so, the monophyly of the Peritrichia could not be rejected when employing statistical tests (Utz and Eizirik, 2007).…”

Molecular and Morphological Characterization of a Poorly Known Marine Ciliate, Myoschiston duplicatum Precht, : Implications for Phylogenetic Relationships between Three Morphologically Similar Genera — Zoothamnium, Myoschiston, and Zoothamnopsis (Ciliophora, Peritrichia, Zoothamniidae)

“…; Utz and Eizirik ; Utz et al. ). The difference between the Vorticellidae and Zoothamniidae in the status of the silverline system as a taxonomic characteristic leads to a conclusion that differences in the silverline system may have evolved earlier in some lineages of peritrichs than others or at a different rate, thus, they may prove to be valid defining characters of genera if the taxa have diverged from one another to a sufficient degree, but should not be used as generic characters without supporting evidence.…”

Revealing the Diversity and Quantity of Peritrich Ciliates in Environmental Samples Using Specific Primer-based PCR and Quantitative PCR

“…Recent studies have also shown that morphological markers underestimate peritrich diversity (18, 43). This demonstrated the importance of using molecular tools to characterize the diversity of both isolated and environmental peritrichs.…”

“…It should be noted that species in the order Operculariida ( e.g. Epistylis galea , Campanella umbellaria , and Opercularia microdiscum , see [43]; Fig. 2) have several mismatches mostly at the 5′ end with these primers.…”