Taxonomy, Ontogenesis and Evolutionary Relationships of the Algae-Bearing Ciliate Bourlandella viridis (Kahl, 1932) comb. nov., With Establishment of a New Genus and New Family (Protista, Ciliophora, Hypotrichia)

Abstract

Hypotrichs are the most complex and highly differentiated ciliate lineages and have great potential for evolutionary novelties. Problems in hypotrich systematics are mainly due to discordance between the morphological and genetic data (mainly small subunit rRNA gene). Species with morphologies that are characteristic of two or more higher rank taxa are probably a major contributing factor to these conflicts. The present study describes a Chinese population of a poorly known organism with numerous endosymbiotic zoochlorellae, the morphology of which corresponds well with the type population of Limnoholosticha viridis (Kahl, 1932) Li et al., 2017. Newly obtained information shows this species has a zigzag midventral cirral pattern that is diagnostic of urostylids, whereas the dorsal ciliature shares features (presence of dorsomarginal kinety and dorsal kinety 3 fragmentation) that are typical of oxytrichids. Molecular phylogenetic analyses reveal a close relationship with oxytrichids. An integrative approach combining morphological, morphogenetic, phylogenetic and ecological analyses indicates that L. viridis represents a new genus and new family which might be an intermediate form between uorstylids and dorsomarginalians. Thus, Bourlandellidae fam. nov. and Bourlandella gen. nov. are here established. Lastly, we speculate that phenotypic convergence and mixtrophy might confer on the new combination, Bourlandella viridis (Kahl, 1932) comb. nov., the ability to adapt to a wide range of environmental conditions.

Refining the “Melting Pot” Genus Holosticha s. l. (Protozoa, Ciliophora, Hypotrichia) Based on Multigene Datasets with Establishment of a New Species Caudikeronopsis monilata sp. nov.

“…However, due to a lack of detailed information on the ciliary pattern, morphogenetic process and molecular data, the taxonomy and systematics of Limnoholosticha viridis (Kahl, 1932) [5] were poorly known. Based on a Chinese population of this uncertain species, Song et al [8] established a new genus Bourlandella for it. Considering its dorsal ciliature shares features (presence of dorsomarginal kinety and dorsal kinety 3 fragmentation) that are typical of oxytrichids, Bourlandella [8] might be an intermediate form between urostylids and dorsomarginalians.…”

“…Based on a Chinese population of this uncertain species, Song et al [8] established a new genus Bourlandella for it. Considering its dorsal ciliature shares features (presence of dorsomarginal kinety and dorsal kinety 3 fragmentation) that are typical of oxytrichids, Bourlandella [8] might be an intermediate form between urostylids and dorsomarginalians.…”

“…Holosticha Wrzesniowski, 1877, has ever been a large and puzzling genus, in which over 100 species were originally assigned to it, and many others were transferred to and excluded from it [1][2][3][4][5][6][7]. With the continuous discovery of new taxa, the phylogenetic analyses based on multigene data provide the opportunity to break the Holosticha s. l. "melting pot," to gain more insights to outline to the taxa in it and to better understand their systematic and evolutionary relationship [8].…”

Further insights into the phylogeny of facultative parasitic ciliates associated with tetrahymenosis (Ciliophora, Oligohymenophorea) based on multigene data

“…Ciliates are a highly differentiated group of microbial eukaryotes that inhabit virtually all environments in the world. They play an important role in the microbial food web through transfer of material and energy (Arregui et al, 2002 ; Azam & Malfatti, 2007 ; Bai et al, 2020 ; Caron et al, 2012 ; Ewa & Sebastian, 2018 ; Gao et al, 2020 ; Kathol et al, 2009 ; Lara et al, 2011 ; Li et al, 2022 ; Liu et al, 2020 ; Luo et al, 2021 ; Pan et al, 2020 ; Pilling et al, 2017 ; Song et al, 2021 ; Wang et al, 2020 ; Weisse, 2017 ; Wu et al, 2021 ).…”

Insights into the phylogeny of the ciliate of class Colpodea based on multigene data

“…Ciliates are a highly differentiated group of microbial eukaryotes that inhabit virtually all environments on the Earth's surface where there is sufficient water for their survival. They play a fundamental role in microbial food web function by mediating the transfer of organic matter and energy between different trophic levels in a wide range of ecosystems (Agatha et al, 2021; Bai et al, 2020; Chi et al, 2021; Dias et al, 2021; Liu et al, 2022; Song et al, 2021; Wang et al, 2021; Weisse & Montagnes, 2021; Wu et al, 2021). Due to their particular nature (e.g., high reproductive capacity, diverse morphology, nuclear dimorphism, chromosomal fragmentation, and sensitivity to environmental changes), ciliates are important model organisms in many disciplines, such as epigenetics, symbiotic relationships, molecular biology, organismal development, evolution, biogeography, and ecology (Berger, 2011; Cheng et al, 2019; Corliss, 1979; Gao et al, 2014; Lynn, 2008; Song et al, 2009; Zhao et al, 2020).…”