The Morphology, Taxonomy, and Phylogenetic Analyses of Five Freshwater Colonial Peritrich Ciliates (Alveolata, Ciliophora), Including the Descriptions of Two New Species.

Tong Wu,Chundi Wang,Saleh A Al-Farraj,Zhe Wang,Alan Warren,Borong Lu,Lili Duan,Hamed El-Serehy,Yujie Liu

doi:10.3389/fmicb.2021.718821

Abstract

The morphology and phylogeny of two new sessilid species, Zoothamnium weishanicum n. sp. and Epicarchesium sinense n. sp., two insufficiently known species, Zoothamnium arbuscula Ehrenberg, 1831 and Zoothamnium hentscheli Kahl, 1935, and a well-known species, Carchesium polypinum (Linnaeus, 1767) Ehrenberg, 1838, collected from freshwater habitats of China, were investigated. Zoothamnium weishanicum n. sp. is characterized by its inverted bell-shaped zooids, double-layered peristomial lip, alternately branched stalk, and two different-length rows in infundibular polykinety 3 (P3). Epicarchesium sinense n. sp. is recognized by its asymmetric-pyriform zooids, single-layered peristomial lip, conspicuous cortical blisters on the pellicle, dichotomously branched stalk, and P3 containing one short inner row and two long outer rows. Based on previous and newly obtained data of the three known species, improved diagnoses and redescriptions are provided including, for the first time, data on the infraciliature of Z. arbuscula and Z. hentscheli. In addition, we analyzed the phylogeny of each species based on SSU rDNA sequence data.

Highlights

Ciliated protists are a group of unicellular eukaryotes with high species diversity and a cosmopolitan distribution (Song et al, 2009; Hu et al, 2019)
The five newly obtained SSU rDNA sequences and 54 sequences of other peritrichs downloaded from GenBank were used for phylogenetic analyses
Foissner et al (1992) made a revision of this species and questioned the identity of marine populations reported under the name Z. arbuscula

Summary

Introduction

Ciliated protists (ciliates) are a group of unicellular eukaryotes with high species diversity and a cosmopolitan distribution (Song et al, 2009; Hu et al, 2019) They have been used widely in a variety of fields of investigation including cytology, evolutionary biology, and ecology (Chen et al, 2020; Wang Y.R. et al, 2019, 2020; Zhang et al, 2020; Zhu et al, 2020). Investigations of sessilids have been carried out for more than 300 years, many species are poorly described since they are known only from in vivo observations and information on their infraciliature, silverline system, and molecular phylogeny is lacking (Kahl, 1935; Precht, 1935; Nenninger, 1948; Sommer, 1951; Stiller, 1971; Bernerth, 1982; Foissner et al, 1992). New species are continuously being reported, suggesting that there is a large undiscovered diversity of sessilids (Canals and Salvadó, 2016; Kühner et al, 2016; Wang et al, 2017; Zhou et al, 2019a,b; Lu et al, 2020; Wu et al, 2020, 2021)

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Results

Conclusion