Ontogeny and Phylogeny of a New Hypotrichous Ciliate (Protista, Ciliophora), Metaurostylopsis alrasheidi n. sp., With Establishment of a New Genus Monourostylopsis n. gen.

Abstract

In the present study, based on both morphologic and phylogenetic analyses, a new genus, Monourostylopsis n. gen., and new species, Metaurostylopsis alrasheidi n. sp. as well as a new combination, Monourostylopsis antarctica (Jung et al., 2011) n. comb. (original combination: Metaurostylopsis antarcticaJung et al., 2011), are suggested. The new genus is diagnosed mainly by having three or more frontoterminal cirri, a midventral complex with midventral pairs and a single midventral row, one right marginal row and two or more left marginal rows. The new genus can be easily separated from the morphologically similar genera mainly by having single right marginal row (vs. two or more right marginal rows). Based on live observation and protargol staining, the morphology and morphogenesis of a new species, M. alrasheidi n. sp. isolated from China, were investigated. The new species can be characterized by: two types of cortical granules; about 22 adoral membranelles; three or four frontoterminal, four or five transverse cirri; about eight midventral pairs and a midventral row of three or four unpaired midventral cirri; three or four left and right marginal rows. The main morphogenetic features of Metaurostylopsis alrasheidi n. sp. can be summarized as: (1) the entire parental ciliature, including the oral apparatus, is renewed; (2) the oral primordium of the proter probably originates within a pouch; (3) the oral primordium of the opisthe forms de novo on the cell surface; (4) the anlagen of marginal rows and dorsal kineties are formed intrakinetally, and (5) the fusion of macronuclear nodules results in an irregular branched mass prior to karyokinesis. In the phylogenetic trees, all the available Metaurostylopsis sequences cluster together in a clade with full support (ML/BI: 100/1.00) revealing that the genus is monophyletic within the large group of core urostylids.

Taxonomy and Molecular Phylogeny of Two New Urostylid Ciliates (Protozoa: Ciliophora) From Chinese Wetlands and Establishment of a New Genus

“…Comparison of Heterobakuella bergeri gen. nov., sp. nov. With Similar Taxa and Basis for the Erection of the Genus Seven urostylid genera with a continuous adoral zone, three frontal cirri, and midventral complex composed of cirral pairs and row(s) should be compared with Heterobakuella gen. nov., namely, Apobakuella, Bakuella, Holostichides, Metaurostylopsis, Monourostylopsis Song et al, 2020, Neobakuella, andParagastrostyla (Berger, 2006;Li et al, 2011;Jiang et al, 2013;Song et al, 2020;Figure 8). Of these, Apobakuella is most similar to Heterobakuella gen. nov. in terms of the cirral pattern.…”

“…nov. can be distinguished from A. fusca by the smaller body size (90-130 × 35-45 µm vs. 150-210 × 50-60 µm), cortical granules (one type vs. two types), buccal cirri (one vs. three to nine), parabuccal cirri (one vs. five to nine arranged in two or three rows), fewer midventral cirral rows with unpaired cirri in posterior portion(s) (one vs. four to nine), and habitat (freshwater vs. brackish). In addition, Heterobakuella gen. nov. can be easily separated from Holostichides and Paragastrostyla by transverse cirri (present vs. absent in Holostichides and Paragastrostyla) (Berger, 2006;Zhu et al, 2019), and from the other four genera by marginal cirral rows (a single left and two right rows vs. a single marginal cirral row on each side in Bakuella; two or more marginal cirral rows on each side in Metaurostylopsis; more than one left and single right marginal cirral rows in Monourostylopsis and Neobakuella), frontoterminal cirri (absent vs. present in Bakuella, Metaurostylopsis, Monourostylopsis, and Neobakuella) (Li et al, 2011;Jo et al, 2015;Lu et al, 2016;Moon et al, 2020;Song et al, 2020;Zhang et al, 2020b). Generic classification of hypotrichs is traditionally based on characteristics of the ciliature and nuclear apparatus in morphostatic and dividing cells (for reviews, see Berger, 1999Berger, , 2006Berger, , 2008Berger, , 2011.…”

“…According to Berger (2006), some urostylid taxa characterized by having three frontal cirri and a midventral complex composed of cirral pairs in the anterior portion and at least one cirral row in the posterior portion were assigned to the family Bakuellidae. Accordingly, at least 10 genera, i.e., Apobakuella Li et al, 2011, Australothrix Blatterer and Foissner, 1988, Bakuella Agamaliev and Alekperov, 1976, Birojimia Berger and Foissner, 1989, Holostichides Foissner, 1987, Metaurostylopsis Song et al, 2001, Monourostylopsis Song et al, 2020, Neobakuella Li et al, 2011, Parabirojimia Hu et al, 2002, and Paragastrostyla Hemberger, 1985 could be assigned to this family (Berger, 2006;Li et al, 2011;Jiang et al, 2013;Song et al, 2020). However, molecular studies showed that the family Bakuellidae was not monophyletic, and some of its genera (e.g., Australothrix, Birojimia, and Parabirojimia) had phylogenetic incongruence between the morphological and molecular data, thus its classification scheme was questioned and some newly established families (e.g., Hemicycliostylidae Lyu et al, 2018 andParabirojimidae Dai and were proposed later (Lynn, 2008;Dai and Xu, 2011;Foissner, 2016;Lyu et al, 2018).…”

Multi-Gene Phylogeny of the Ciliate Genus Trachelostyla (Ciliophora, Hypotrichia), With Integrative Description of Two Species, Trachelostyla multinucleata Spec. nov. and T. pediculiformis (Cohn, 1866)

“…Ciliates (phylum Ciliophora Doflein, 1901) are a large group of unicellular eukaryotes with various lifestyles, including endosymbiotic, epibiotic, and free-living ( Van As and Basson, 2004 ; Bai et al, 2020 ; Wu et al, 2020 ; Foissner and Berger, 2021 ; Zhao et al, 2021 ). Hypotrichs (subclass Hypotrichia Stein, 1859) are not only one of the most morphologically differentiated ciliate groups, but also one of the most confused in terms of systematics and phylogeny (for reviews, see Berger, 1999 , 2006 , 2008 , 2011 ; Chen L. et al, 2020 , 2021 ; Paiva, 2020 ; Song et al, 2020 ; Xu W. et al, 2020 ; Xu Y. et al, 2020 ; Wang et al, 2020 ; Zhang et al, 2020a ; Jung et al, 2021 ; Li et al, 2021a , b ; Luo et al, 2021 ; Vd’ačný and Foissner, 2021 ). In the past decades, identification of hypotrichs mostly relied on interphase morphology, ontogenetic processes, and gene encoding for the small subunit (18S) rRNA molecule ( Foissner, 2016 ; Song and Shao, 2017 ; Jung and Berger, 2019 ; Kaur et al, 2019 ; Kim and Min, 2019 ; Ma et al, 2021 ; Wang et al, 2021a ).…”