Taxonomy and Molecular Phylogeny of Two New Species of Prostomatean Ciliates With Establishment of Foissnerophrys gen. n. (Alveolata, Ciliophora).

Limin Jiang,Alan Warren,Xiaozhong Hu,Hamed A El-Serehy,Saleh A Al-Farraj,Wenbao Zhuang

doi:10.3389/fmicb.2021.686929

Limin Jiang, Alan Warren + Show 4 more

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https://doi.org/10.3389/fmicb.2021.686929

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Abstract

Prostomatean ciliates play important roles in the flow of material and energy in aquatic microbial food webs, and thus have attracted wide attention for over a century. Their taxonomy and systematics are, however, still poorly understood because of their relatively few taxonomically informative morphological characters. In this study, two new prostomateans, Lagynus binucleatus sp. n. and Foissnerophrys alveolata gen. n., sp. n., collected from a freshwater pool and the intertidal zone of a sandy beach, respectively, in Qingdao, China, are investigated using living observation, protargol staining, and SSU rRNA gene sequencing methods. The genus Lagynus is redefined, and the new species L. binucleatus sp. n. is established based on significant morphological differences with similar forms. Furthermore, a new genus, Foissnerophrys gen. n., is established based on a combination of morphological and molecular data with F. alveaolata sp. n. the type species by monotypy. The identities of intracellular prokaryotes of these two new species are discussed based on fluorescence in situ hybridization (FISH) data and newly obtained 16S rRNA gene sequences.

Highlights

The class Prostomatea Schewiakoff, 1896 is one of the smallest in the phylum Ciliophora Doflein, 1901 in terms of species and genus richness (Lynn, 2008)
Improved Diagnosis The body was bottle-shaped or spindle-shaped, rounded in crosssection; cytostome apical; neck region encircled by furrows and slightly contractile; macronuclear nodule(s) ovoidal; circumoral kinety composed of dikinetids; three or four brosse kineties; perioral kineties present; and caudal cilium absent
L. elegans differs from L. binucleatus sp. n. by having three to five conspicuous annular furrows in the neck region and in the composition of the brosse, i.e., three or four rows, each with four to six kinetosomes in L. elegans vs. three rows, each comprising a pair of kinetosomes in L. binucleatus sp. n. (Figure 3G; Sola et al, 1990; Foissner et al, 1995) (Table 2)

Summary

Introduction

The class Prostomatea Schewiakoff, 1896 is one of the smallest in the phylum Ciliophora Doflein, 1901 in terms of species and genus richness (Lynn, 2008). As abundant components of aquatic ecosystems, prostomateans play several important ecological roles utilizing a wide range of bacteria and microalgae as food (Madoni et al, 1990; Epstein and Shiaris, 1992; Šimek et al, 1996; Weisse and Montagnes, 1998; Nakamura and Hirata, 2006; Lynn, 2008). The marine genus Tiarina Bergh, 1881 has been reported to control the growth. Symbiotic bacteria have been discovered in Urotricha ovata Kahl, 1926 (de Puytorac and Grain, 1972), and the microalga Symbiodinium has been found in a calcifying Tiarina (Mordret et al, 2016). Species identification and evolutionary relationships of prostomateans remain difficult due to the lack of ciliature information and molecular data

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