Pleurostomatid ciliates,as a highly diverse and widely distributed unicellular eukaryote group,play a crucial role in the cycling of nutrients and energy in microbial food webs.However,research on pleurostomatids rema...Pleurostomatid ciliates,as a highly diverse and widely distributed unicellular eukaryote group,play a crucial role in the cycling of nutrients and energy in microbial food webs.However,research on pleurostomatids remains insufficient,resulting in a paucity of molecular information and substantial gaps in knowledge of their phylogenetic relationships.In recent years,we investigated pleurostomatid diversity in various Chinese habitats,including their systematic relationships and taxonomic circumscriptions,which were comprehensively analyzed using an integrative morphomolecular approach.Results revealed that:(1)pleurostomatids can be categorized into two suborders,Protolitonotina subord.nov.and Amphileptina Jankowski,1967;(2)Protolitonotina subord.nov.represents the ancestral pleurostomatid group and includes two genera,Protolitonotus and Heterolitonotus gen.nov.,characterized by right kineties progressively shortened along rightmost full kineties and absence of a left dorsolateral kinety;(3)Heterolitonotus gen.nov.represents an orphan lineage and is defined by an oral slit extending to its dorsal margin;(4)“Protolitonotus clampi”does not group with congeners but instead represents an orphan lineage,thus Novilitonotus gen.nov.is established to which P.clampi is transferred as Novilitonotus clampi comb.nov.;(5)three new species,Apoamphileptus paraclaparedii sp.nov.,Heterolitonotus rex gen.nov.,sp.nov.,and Loxophyllum apohelus sp.nov.,are described;and(6)helices 21es6a to 21es6d within the V4 region of small subunit ribosomal RNA(SSU rRNA)may serve as a useful tool for discriminating pleurostomatids.The evolutionary relationships among all main lineages of pleurostomatids are discussed and a key to the identification of pleurostomatid genera is provided.展开更多
The well-known ciliate, Mesodinium Stein, 1863, is of great importance to marine microbial food webs and is related to the ＂red tides＂. However, it is possibly one of the most confusing ciliate taxa in terms of its ...The well-known ciliate, Mesodinium Stein, 1863, is of great importance to marine microbial food webs and is related to the ＂red tides＂. However, it is possibly one of the most confusing ciliate taxa in terms of its systematic position： either the morphological or the molecular data excluded it from all the other known assemblages or groups. In the current work, the sequences of small subunit ribosomal RNA （SSU rRNA） genes for all isolates available are analysed and an examination of the secondary structure patterns of related groups is carried out. The results indicate that （1） Mesodiniurn invariably represents a completely separated and isolated clade positioned between two subphyla of ciliates with very deep branching, which indicates that they should be a primitive or ancestral group for the subphylum Intramacronucleata; （2） the secondary structure of the SSU rRNA of Mesodinium species is unusual in that, while the secondary structure of V4 in Mesodinium sp. has the deletions common to all litostome ciliates, it has more extensive deletions in helix E23_8 and a longer helix E23_1; （3） combining the phylogenetic and morphological information, we suggest establishing Mesodiniea el. nov., including the order Mesodiniida Grain, 1994, belonging to the subphylum Intramacronucleata.展开更多
基金supported by the National Natural Science Foundation of China(32030015,32170533)Researchers Supporting Project Number(RSP2024R10)King Saud University,Riyadh,Saudi Arabia。
文摘Pleurostomatid ciliates,as a highly diverse and widely distributed unicellular eukaryote group,play a crucial role in the cycling of nutrients and energy in microbial food webs.However,research on pleurostomatids remains insufficient,resulting in a paucity of molecular information and substantial gaps in knowledge of their phylogenetic relationships.In recent years,we investigated pleurostomatid diversity in various Chinese habitats,including their systematic relationships and taxonomic circumscriptions,which were comprehensively analyzed using an integrative morphomolecular approach.Results revealed that:(1)pleurostomatids can be categorized into two suborders,Protolitonotina subord.nov.and Amphileptina Jankowski,1967;(2)Protolitonotina subord.nov.represents the ancestral pleurostomatid group and includes two genera,Protolitonotus and Heterolitonotus gen.nov.,characterized by right kineties progressively shortened along rightmost full kineties and absence of a left dorsolateral kinety;(3)Heterolitonotus gen.nov.represents an orphan lineage and is defined by an oral slit extending to its dorsal margin;(4)“Protolitonotus clampi”does not group with congeners but instead represents an orphan lineage,thus Novilitonotus gen.nov.is established to which P.clampi is transferred as Novilitonotus clampi comb.nov.;(5)three new species,Apoamphileptus paraclaparedii sp.nov.,Heterolitonotus rex gen.nov.,sp.nov.,and Loxophyllum apohelus sp.nov.,are described;and(6)helices 21es6a to 21es6d within the V4 region of small subunit ribosomal RNA(SSU rRNA)may serve as a useful tool for discriminating pleurostomatids.The evolutionary relationships among all main lineages of pleurostomatids are discussed and a key to the identification of pleurostomatid genera is provided.
基金supported by the National Natural Science Foundation of China(31272285,41276139)King Saud University Deanship of Scientific Research(Research Group Project No.RGP-083)Special Foundation B of President of the Chinese Academy of Sciences(Y25102EN00)
文摘The well-known ciliate, Mesodinium Stein, 1863, is of great importance to marine microbial food webs and is related to the ＂red tides＂. However, it is possibly one of the most confusing ciliate taxa in terms of its systematic position： either the morphological or the molecular data excluded it from all the other known assemblages or groups. In the current work, the sequences of small subunit ribosomal RNA （SSU rRNA） genes for all isolates available are analysed and an examination of the secondary structure patterns of related groups is carried out. The results indicate that （1） Mesodiniurn invariably represents a completely separated and isolated clade positioned between two subphyla of ciliates with very deep branching, which indicates that they should be a primitive or ancestral group for the subphylum Intramacronucleata; （2） the secondary structure of the SSU rRNA of Mesodinium species is unusual in that, while the secondary structure of V4 in Mesodinium sp. has the deletions common to all litostome ciliates, it has more extensive deletions in helix E23_8 and a longer helix E23_1; （3） combining the phylogenetic and morphological information, we suggest establishing Mesodiniea el. nov., including the order Mesodiniida Grain, 1994, belonging to the subphylum Intramacronucleata.
