Morphological Redescription and SSU rDNA-based Phylogeny of Two Freshwater Ciliates, Uronema nigricans and Lembadion lucens (Ciliophora, Oligohymenophorea), with Discussion on the Taxonomic Status of Uronemita sinensis

Liu, Mingjian, Li, Lifang, Qu, Zhishuai, Luo, Xiaotian, Al-Farraj, Saleh A., Lin, Xiaofeng, Hu, Xiaozhong (2017): Morphological Redescription and SSU rDNA-based Phylogeny of Two Freshwater Ciliates, Uronema nigricans and Lembadion lucens (Ciliophora, Oligohymenophorea), with Discussion on the Taxonomic Status of Uronemita sinensis. Acta Protozoologica 56 (1): 17-37, DOI: 10.4467/16890027AP.17.003.6967, URL: https://www.mendeley.com/catalogue/cb3bc4f7-739f-32f8-92cd-7da31a838cb6

Taxonomic Descriptions of Two Marine Ciliates, Euplotes dammamensis n. sp. and Euplotes balteatus (Dujardin, 1841) Kahl, 1932 (Ciliophora, Spirotrichea, Euplotida), Collected from the Arabian Gulf, Saudi Arabia

The morphology, morphogenesis and infraciliature of two marine euplotid ciliates, Euplotes dammamensis n. sp. and Euplotes balteatus (Dujardin, 1841) Kahl, 1932, isolated from a sandy beach of the Arabian Gulf, Saudi Arabia, were investigated using observations in vivo and protargol-impregnation methods. Euplotes dammamensis n. sp. is characterized by a combination of features including its huge body size (100–170 × 80–120 μm), 10 conspicuous dorsal ridges, 10 normal-sized frontoventral and two marginal cirri, and 11 dorsal kineties. Euplotes balteatus is mainly characterized by 10 frontoventral, two caudal, and two left marginal cirri, 7–10 dorsal kineties and 5–7 prominent dorsal ridges as well as double-eurystomus silverline system. The small subunit rRNA (SSU-rRNA) gene sequences were determined for both species and phylogenetic analyses based on these data indicated that E. dammamensis is most closely related to E. parabalteatus Jiang et al., 2010, and E. balteatus clusters with E. plicatum Valbonesi et al., 1997, E. orientalis Jiang et al., 2010, and E. bisulcatus Kahl, 1932

Taxonomic Studies on Three Marine Ciliates from China, Including a New Species (Ciliophora, Cyrtophorida)

The present work investigates the living morphology and infraciliature of three marine cyrtophorid ciliates, which were isolated from Qingdao, China. Compared with its congeners, Orthotrochilia sinica spec. nov. can be distinguished by a combination of features: body slender and elliptical in outline, size about 50–60 × 20–25 μm in vivo, 18–21 somatic kineties, the length of the left perioral kinety treble the length of the right one, two ventrally located contractile vacuoles on the right side, and 25–32 nematodesmal rods. Based on current observations and the previous description, the diagnosis of Trochilioides tenuis (Deroux, 1976) Chen et al. 2011 is improved: cell size 30–40 × 20–35 μm in vivo, oval shaped in outline; consistently three right kineties, four left kineties and seven postoral kineties; a single contractile vacuole; marine habitat. A second species of Trochilioides, T. recta (Kahl, 1923) Chen et al. 2011 is re-described based on a Chinese population. Furthermore, a key to the identification of species of the genus Trochilioides whose infraciliature data are available is supplied, and Chlamydonyx trivialis (Fenchel, 1965) comb. nov. [basionym: Trochilioides trivialis Fenchel, 1965] is suggested

Timing and characteristics of nuclear events during conjugation and genomic exclusion in Paramecium multimicronucleatum

Ciliated protists are ideal material for studying the origin and evolution of sex, because of their nuclear dimorphism (containing both germline micronucleus and somatic macronucleus in the same cytoplasm), special sexual processes (conjugation and autogamy), and high diversity of mating-type systems. However, the study of sexual process is limited to only a few species, due to the difficulties in inducing or observing conjugation. In the present study, we investigate the conjugation process in Paramecium multimicronucleatum: (1) of the three prezygotic divisions, all micronuclei undergo the first two divisions (meiosis I, II), while a variable number of nuclei undergo the third division (mitosis); (2) the synkaryon divides three times after fertilization, giving rise to eight products that differentiate into four macronuclear anlagen and four micronuclei; (3) cells restore the vegetative stage after two successive cell fissions during which the macronuclear anlagen are distributed into daughter cells without division, while micronuclei divide mitotically; (4) the parental macronucleus begins to fragment following the first meiotic division and finally degenerates completely; (5) the entire process takes about 110 h, of which about 85 h are required for macronuclear development. In addition, we describe for the first time the process of genomic exclusion occurring between amicronucleate and micronucleate cells of P. multimicronucleatum, during which the micronucleate cell contributes a pronucleus to the amicronucleate cell, resulting in both exconjugants being homozygotes. These results provide new insights into the diversity of sexual processes and lay an important cytological basis for future in-depth studies of mating systems in ciliates

The Diversity of Scuticociliates (Protozoa, Ciliophora): A Report on Eight Marine Forms Found in Coastal Waters of China, with a Description of One New Species

Eight marine scuticociliates, Pseudoplatynematum denticulatum (Kahl, 1933) nov. comb., Protocyclidium sinica nov. spec., Histiobalantium marinum Kahl, 1933, Porpostoma notata Möbius, 1888, Philaster hiatti Thompson, 1969, Parauronema longum Song, 1995, Uronemella parafilificum Gong et al., 2007, and Paranophrys magna Borror, 1972, collected from Chinese coastal waters, were investigated using live observations and silver impregnation methods. Investigations of a Chinese population of Platynematum denticulatum (Kahl, 1933) reveal that it has a highly strengthened pellicle and distinct spines and thus corresponds well with the definition of Pseudoplatynematum Bock, 1952. A new combination, Pseudoplatynematum denticulatum (Kahl, 1933) nov. comb., is therefore proposed and an improved species diagnosis is supplied. Protocyclidium sinica nov. spec. is characterized by: small body size with buccal field approximately 60% of body length; extrusomes present; 13 or 14 somatic kineties; somatic kinety 1 comprising approximately 24 densely arranged kinetids; somatic kinety n shortened posteriorly; single macronucleus. Additional information is documented on the morphology of six other species of scuticociliates based on the China populations

A Morphogenetic Description of Thigmokeronopsis stoecki Shao et al., 2008 (Ciliophora, Hypotricha) and a Comparison with Members of the Family Pseudokeronopsidae

The urostylid family Pseudokeronopsidae Borror and Wicklow, 1983 was considered to be a well-outlined taxon. Nevertheless, recent evidence, including morphological, ontogenetic, and molecular information, has consistently revealed the polyphyly of this family. In the present work, a new population of Thigmokeronopsis stoecki Shao et al., 2008 was found and its binary divisional process was described for the first time. In addition, the morphogenetic features of Thigmokeronopsis species and all the other pseudokeronopsids, for which detailed ontogenetic data are available, were rechecked and compared. This reveals that: (1) the ontogenetic process of T. stoecki corresponds well with its congeners T. jahodai and T. rubra except for the macronuclear behavior; (2) Apokeronopsis and Thigmokeronopsis share a similar ontogenetic mode despite of the differences in the number and origin of their buccal cirri; (3) most pseudokeronopsids share the same pattern in the origins of their oral primordia and fronto-ventral-transverse cirral anlagen, except for Pseudokeronopsis similis, which may not be a valid member of the family Pseudokeronopsidae

Systematic Analyses of the Genus Architricha and Pleurotricha curdsi (Ciliophora, Oxytrichidae), with Redescriptions of Their Morphology

Two oxytrichids Architricha indica Gupta et al., 2006 and Pleurotricha curdsi (Shi et al. 2002) Gupta et al., 2003 collected in East China, were studied using live observation and the silver staining method. The description and morphometric characterization of the new populations were supplied. The Shanghai population of A. indica differs from the Indian population in the number of cirri in the third right marginal row (average of 16.8 vs. 21.1). The Shanghai population of P. curdsicorresponds well with the Indian population, but it differs from the other Chinese population in the number of right marginal rows (two vs. three). The early process of reorganization of A. indica was studied, and a difference on the formation of anlage V was found compared to the original report. The small subunit rRNA genes of both species were sequenced for the first time. The phylogenetic analyses based on SSU rRNA gene sequence data revealed that Architricha is sister to the assemblage of Pseudouroleptus caudatus and two Strongylidium, while P. curdsi clusters with its congener P. lanceolata and is located in Stylonychinae

Morphological and Morphogenetic Redescriptions and SSU rRNA Gene-based Phylogeny of the Poorly-known Species Euplotes amieti Dragesco, 1970 (Ciliophora, Euplotida)

This paper investigates the morphology and morphogenesis during binary fission of a Chinese population of Euplotes amieti Dragesco, 1970, a fresh water form which has previously not been well defined. This organism is morphologically very similar to the well-known Euplotes eurystomus but differs from the latter both in the number of dorsal kineties and the molecular data. According to the information obtained, it is characterized by a combination of features including nine frontoventral cirri, ca. 60 membranelles, 12–15 dorsal kineties, a macronucleus in the shape of the number 3, and a ‘double-eurystomus’ type of silverline system. Its morphogenesis proceeds broadly in the same pattern as in its congeners. In this study, the SSU rRNA gene was sequenced for the first time, and phylogenetic analyses indicated that it is closely related to the eurystomus-aediculatus-woodruffi- complex. Considering the extreme similarities in morphology between E. amieti and E.eurystomus, we believe that the four sequences (four isolates) under the name of Euplotes eurystomus (No. FR873716; FR873717; EF193250; AJ310491 deposited in GenBank) are very likely from misidentified material; that is, they represent different populations of Euplotes amieti

Morphology of Two Novel Species of Chaenea (Ciliophora, Litostomatea): Chaenea paucistriata spec. nov. and C. sinica spec. nov.

During faunistic studies of ciliates in coastal waters of Daya Bay and Bohai Bay, China, two previously unknown ciliates were discovered and investigated using standard taxonomic methods. Morphological comparative analyses revealed that they represent two novel species in the genus Chaenea. Chaenea paucistriata spec. nov. can be distinguished from its congeners by the following traits: body length in vivo about 180–250 µm; eight somatic kineties; dorsal brush rows 1–4 consisting of three, five, seven, and two dikinetids, respectively; rod-like extrusomes, 8 µm long; 63–94 macronuclei; cortical granules minute and colourless. Chaenea sinica spec. nov. differs from its congeners in having: body length in vivo about 140–240 µm; 17–21 somatic kineties; dorsal brush rows 1–4 consisting of 3–7, 10 or 11, 11–13, and 3–6 dikinetids, respectively; rod-like extrusomes about 6–8 µm long; 71–164 macronuclei. A key is presented to assist the identification of all Chaenea species

Redescriptions of two Marine Scuticociliates from China, with notes on Stomatogenesis in Parauronema longum (Ciliophora, Scuticociliatida)

The morphology and infraciliature of two marine scuticociliates, Pleuronema puytoraci Grolière and Detcheva, 1974, and Parauronema longum Song, 1995, collected from China, were investigated using live observation and protargol impregnation methods. Based on the data obtained for the China population, new information of the living morphology of Pleuronema puytoraci is documented and details of the complete infraciliature is available for the first time. The stomatogenesis of Parauronema longum is basically similar to that of its congeners and can be summarized as follows: membranelle 1, membranelle 2 and the scutica of the opisthe originate from the parental paroral membrane, whereas membranelle 3 of the opisthe develops from the parental scutica; the paroral membrane originates from the parental paroral membrane