Kuidong Xu

Morphology and Infraciliature of Three Species of Metaurostylopsis (Ciliophora, Stichotrichia): M. songi n. sp., M. salina n. sp., and M. marina (Kahl 1932) from Sediments, Saline Ponds, and Coastal Waters

Abstract. Two new urostylid ciliates, Metaurostylopsis songi n. sp. and Metaurostylopsis salina n. sp. and Metaurostylopsis marina ( Kahl 1932 ) are investigated using live observation and protargol impregnation. These species were isolated in Korea from intertidal sediments, saline ponds, and coastal waters. Metaurostylopsis songi is in vivo about 120 μm × 25 μm, has a slenderly ellipsoidal body, colorless cortical granules in rows on ventral and dorsal body sides, about 54 macronuclear nodules, 28–47 adoral membranelles, five frontal, two or three frontoterminal and six or seven transverse cirri, and 9–12 midventral cirral pairs followed posteriorly by 1–3 single cirri. In vivo M. salina is about 60 μm × 25 μm, has a pyriform body, colorless cortical granules irregularly arranged, about 45 macronuclear nodules, 18–23 adoral membranelles, three frontal, three to five frontoterminal and two to five transverse cirri, and four or five midventral cirral pairs followed posteriorly by five to seven single cirri. Both species have three marginal cirral rows on each body side and 3 long dorsal kineties. The Korean specimens of M. marina match the Chinese population in all main features. Metaurostylopsis songi differs from M. marina by the more slender body, the number of frontal cirri (invariably five vs. four), and the arrangement of cortical granules (in rows on dorsal and ventral cortex vs. only along dorsal kineties and anterior body margin). Metaurostylopsis salina differs from its congeners by the distinctly smaller size, the pyriform body shape, the scattered cortical granules (vs. in rows), and number of frontal cirri. It differs from M. marina also by the number of midventral cirral pairs (four or five vs. seven to 11).

Reconsideration of Phylogenetic Relationships of the Subclass Peritrichia (Ciliophora, Oligohymenophorea) Based on Small Subunit Ribosomal RNA Gene Sequences, with the Establishment of a New Subclass Mobilia Kahl, 1933

ABSTRACT. Based on its characteristic oral apparatus, the ciliate subclass Peritrichia has long been recognized as a monophyletic assemblage composed of the orders Mobilida and Sessilida. Following the application of molecular methods, the monophyly of Peritrichia has recently been questioned. We investigated the phylogenetic relationships of the peritrichous ciliates based on four further complete small subunit ribosomal RNA sequences of mobilids, namely Urceolaria urechi, Trichodina meretricis, Trichodina sinonovaculae, and Trichodina ruditapicis. In all phylogenetic trees, the mobilids never clustered with the sessilids, but instead formed a monophyletic assemblage related to the peniculines. By contrast, the sessilids formed a sister clade with the hymenostomes at a terminal position within the Oligohymenophorea. We therefore formally separate the mobilids from the sessilids (Peritrichia sensu stricto) and establish a new subclass, Mobilia Kahl, 1933 , which contains the order Mobilida Kahl, 1933 . We argue that the oral apparatus in the mobilians and sessilid peritrichs is a homoplasy, probably due to convergent evolution driven by their similar life‐styles and feeding strategies. Morphologically, the mobilians are distinguished from all other oligohymenophoreans by the presence of the adhesive disc, this character being a synapomorphy for the Mobilia.

Community structure and seasonal dynamics of planktonic ciliates along salinity gradients

The ciliate community structure and seasonal dynamics in a solar saltern of the Yellow Sea were studied based on 4 sampling dates and 8 stations with salinities from 27.7 per thousand to 311.0 per thousand. The effects of the type and concentration of the fixative used (Lugols and Bouins) were tested at the first sampling date. Fixative type and fixative concentration had significant effects on ciliate abundance and biovolume, with 1% Lugols giving the best results. A detailed investigation using live observations and protargol staining techniques revealed a total of 98 morphospecies from 8 sampling stations. There was obvious seasonal variation in species composition at most of the stations, but this tended to be less distinct with increasing salinity, as the dominant ciliate group shifted from oligotrichs to heterotrichs. Ciliate abundance varied from 4.40 x 10(1) to 2.11 x 10(5) cellsl(-1) and biomass ranged between 2.39 and 9.87 x 10(3)microg Cl(-1) (at a salinity of 147.6 per thousand). Both abundance and biomass decreased abruptly when salinity exceeded 100-150 per thousand. Statistical analyses suggested that the dynamics of ciliate abundance and biomass were regulated by both salinity and by season, but those of diversity and species richness were mainly controlled by salinity and both significantly decreased with increasing salinity.

Morphology and Molecular Phylogeny of Trimyema koreanum n. sp., a Ciliate from the Hypersaline Water of a Solar Saltern

ABSTRACT. A new ciliate, Trimyema koreanum n. sp., isolated from hypersaline water (salinity of 293‰) from a solar saltern in Korea, was investigated using live observation, protargol impregnation, and gene sequencing. Trimyema koreanum is about 30 × 13 μm in vivo, has usually 23 longitudinal ciliary rows forming two distinct ciliary girdles visible both in vivo and in protargol impregnation. A third indistinct ciliary girdle as well as a girdle of mucocysts is distinguishable only in impregnated cells. We suggest T. koreanum as a new species, differing from the most similar species, T. marinum, by the presence of two distinct ciliary girdles (T. marinum usually has six ciliary girdles clearly visible in living cells and three anterior spirals that encircle the cell completely). Although the number of known 18S rRNA sequences in the genus Trimyema was limited, the Trimyema group including T. koreanum forms a strong clade. The phylogenetic position confirms that the isolate belongs to the genus Trimyema and is different from previously sequenced species. Trimyema koreanum is able to consume both prokaryotes and small eukaryotes (specifically, the alga Dunaliella sp.).

Beyond the “Code”: A Guide to the Description and Documentation of Biodiversity in Ciliated Protists (Alveolata, Ciliophora)

Recent advances in molecular technology have revolutionized research on all aspects of the biology of organisms, including ciliates, and created unprecedented opportunities for pursuing a more integrative approach to investigations of biodiversity. However, this goal is complicated by large gaps and inconsistencies that still exist in the foundation of basic information about biodiversity of ciliates. The present paper reviews issues relating to the taxonomy of ciliates and presents specific recommendations for best practice in the observation and documentation of their biodiversity. This effort stems from a workshop that explored ways to implement six Grand Challenges proposed by the International Research Coordination Network for Biodiversity of Ciliates (IRCN‐BC). As part of its commitment to strengthening the knowledge base that supports research on biodiversity of ciliates, the IRCN‐BC proposes to populate The Ciliate Guide, an online database, with biodiversity‐related data and metadata to create a resource that will facilitate accurate taxonomic identifications and promote sharing of data.

Alpha-Tubulin and Small Subunit rRNA Phylogenies of Peritrichs Are Congruent and Do Not Support the Clustering of Mobilids and Sessilids (Ciliophora, Oligohymenophorea)

ABSTRACT. Peritrich ciliates have been traditionally subdivided into two orders, Sessilida and Mobilida within the subclass Peritrichia. However, all the existing small subunit (SSU) rRNA phylogenetic trees showed that the sessilids and mobilids did not branch together. To shed some light on this disagreement, we tested whether or not the classic Peritrichia is a monophyletic group by assessing the reliability of the SSU rRNA phylogeny in terms of congruency with α‐tubulin phylogeny. For this purpose, we obtained 10 partial α‐tubulin sequences from peritrichs and built phylogenetic trees based on α‐tubulin nucleotide and amino acid data. A phylogenetic tree from the α‐tubulin and SSU rRNA genes in combination was also constructed and compared with that from the SSU rRNA gene using a similar species sampling. Our results show that the mobilids and sessilids are consistently separated in all trees, which reinforces the idea that the peritrichs do not constitute a monophyletic group. However, in all α‐tubulin gene trees, the urceolariids and trichodiniids do not group together, suggested mobilids may not be a monophyletic group.

A practical method of Ludox density gradient centrifugation combined with protargol staining for extracting and estimating ciliates in marine sediments

Methodological impediments have long been the main problem in estimating the ecological role of marine benthic ciliates. Percoll density centrifugation is currently the most efficient technique for extracting ciliates from fine-grained sediments, while the high cost and low density of Percoll limit its wide application. We developed a protocol of density gradient centrifugation using the cheap sol Ludox HS 40 in combination with the quantitative protargol stain (QPS) to enumerate and identify marine benthic ciliates. The combined Ludox-QPS method involves sample collection and salt reduction, extraction with Ludox centrifugation, and preparation with the QPS technique. The recovery efficiency of Ludox was first tested with azoic sandy and muddy sediments. A 94-100% recovery rate of ciliates was reached. The method was further tested with natural sandy, muddy-sand and muddy sediments. Excellent extraction efficiencies were consistently obtained: an average of 97.6% for ciliates in sand, and 96.9-97.8% for nematodes in the three types of sediments. The high efficiencies indicate that the method allows for simultaneous enumeration of micro- and meiobenthos. Advantages of the new method include: (i) reliable and cost-efficient operation; (ii) appropriate centrifugation for both micro- and meiobenthos; and (iii) applicability to large samples and routine ecological surveys.

Trichodinid ectoparasites (Ciliophora: Peritrichida) of some marine fishes from coastal regions of the Yellow Sea and Bohai Sea

Five species of marine fishes, including two of the main maricultured fishes from coastal regions of the Yellow Sea and Bohai Sea, were examined for ectoparasitic trichodinids. A total of five species of trichodinids belonging to three genera, Trichodina Ehrenberg, 1830, Paratrichodina Lom, 1963 and Trichodinella Šrámek-Hušek, 1953 were reinvestigated following dry silver impregnation. These were: Trichodina rectuncinata Raabe, 1958, T. jadranica (Raabe, 1958) Haider, 1964, Paratrichodina globonuclea Lom, 1963, P. obliqua Lom, 1963 and Trichodinella lomi Xu, Song & Warren, 1999. Morphometric data and comparative descriptions of these trichodinids are provided along with details of their prevalence and intensity of infestation.

Trichodinid ectoparasites (Ciliophora: Peritrichida) from the gills of cultured marine fishes in China, with the description of Trichodinella lomi n. sp.

Three species of cultured percoids, each heavily infested by trichodinid ectoparasites, were examined from overwintering pools in Qingdao, China during the winter of 1995. A total of five species of trichodinids belonging to three genera, Trichodinella Sramek-Husek, 1953, Dipartiella Shtein, 1961 and Trichodina Ehrenberg, 1838 were recorded. One new species, Trichodinella lomi n. sp., is described, the denticle of which is characterised by its acutely triangular blade, comma-like central part and inconspicuous ray. The morphology of Trichodina murmanica Poljansky, 1955 was re-investigated. Three other little-known species are redescribed: Dipartiella simplex (Raabe, 1959) Shtein, 1961, Trichodina japonica Imai, Miyazaki & Nomura, 1991 and T. domerguei (Wallengren, 1897).

Trichodinid ectoparasites (Ciliophora: Peritrichida) from the gills of mariculture molluscs in China, with the descriptions of four new species of Trichodina Ehrenberg, 1838.

Four new species of the genus Trichodina, found on gills of marine molluscs from aquaculture beds off the coast of Qingdao (Tsingao), China, are described: T. chlamydis n. sp. from Azumapecten (Chlamys) farreri (Pectinidae), T. sinonovaculae n. sp. from Sinonovacula constricta (Solenidae), T. liana n. sp. from Solen (Plectosolen) gracilis (Solenidae) and T. meretricis n. sp. from Meretrix meretrix (Veneridae). The descriptions presented here include morphometric data obtained from examinations of specimens prepared using the wet silver nitrate and protargol- impregnation techniques. Comparisons with closely related species are provided for each of the four.