Paracineta sp., an Epizoic Suctorian Found on Gulf of Maine Copepoda

SYNOPSIS. An epizoic suctorian from Gulf of Maine coastal waters, designated as Paracineta sp., is described. Morphological measurements are given for 23 small, medium, and large specimens. Mean length was 200 μ and average cell body diameter 39 μ. Of 21 copepod species and 19 zooplankton groups examined, only copepods of the genus Metridia showed any Paracineta attached. Suctorian occurrence was, with a single exception, limited to adult copepods, with the larger females showing the heaviest incidence. Differences in areal occurrence were observed with greatest incidence of Paracineta on M. lucens in the eastern and central Gulf, and lowest numbers in the western area. This differential occurrence is accredited to an apparent cold water affinity of the suctorian. It is suggested that Paracineta could be carried into the Gulf during periodic intrusions of cool Nova Scotian water, reaching the western area in the southwesterly flowing Gulf of Maine eddy system. No significant differences in vertical distribution were found in Paracineta incidence on Metridia among the depths sampled (0, 10, 30, and 60 m). No harmful effect of Paracineta on Metridia was evident.     

The morphology and life cycle of Ophryodendron mysidacii sp. nov. a marine suctorian epibiont on a mysid crustacean

A new species of suctorian protist epibiont of the mysid Schistomysis parkeri is described. The individuals show two types of adult form: elongated and flattened, both with 4-8 tentacular lobes. This new suctorian differs from described species of pro-Ophryodendron group by size, number of tentacular lobes, insertion of the tentacles, union of the lorica with the body, shape of the macronucleus, number of micronuclei and the lack of stalk (adult forms). The life cycle of this species is analysed and a succession pattern of its different stages is proposed.     

Periacineta mexicana n. sp. (Ciliophora,Suctoria, Discophryida), Epizoic on Mexican Backswimmers of the Genus Buenoa (Insecta,Hemiptera, Notonectidae)

ABSTRACT. A new species of suctorian in the genus Periacineta, epibiotic on aquatic bugs (Hemiptera, Heteroptera, Nepomorpha), is described on the basis of morphological characteristics of the cell body, lorica, tentacular placement, and stalk, and its 18S rRNA partial sequence gene. Periacineta mexicana n. sp. is a loricate suctorian with elongate body and rounded apical region; tentacles are distributed randomly over apical region and not grouped into fascicles. Macronucleus in adult is elongate and located centrally. The suctorian usually forms closely aggregated pseudocolonies. We provide morphological data based on optical and scanning electron microscopy. A comparison with similar congeners, and emended diagnosis of the genus Periacineta also are provided. The ciliates were found attached to the first two pairs of legs of Mexican notonectids Buenoa pallens and Buenoa spp. (backswimmers).     

Description of a new epibiotic relationship (Suctorian–Copepoda) in NE Atlantic waters: from morphological to phylogenetic analyses

Paraeuchaeta hebes is one of the most important carnivorous copepods in the coastal upwelling system off Galician waters (Ría de Vigo, NE Atlantic). A suctorian epibiont of the genus Pelagacineta was found attached to the surface of these copepods. The abundance and distribution on the copepod surface were analysed, taking into account the sex of the crustacean, revealing some preference for females and also a different attachment point in both sexes. The morphological study allowed us to identify a new species of this Suctoria epibiont as Pelagacineta hebensis. Moreover, the 18S rRNA gene was partially sequenced to inspect the phylogenetic position of Pelagacineta hebensis within the subclass Phyllopharyngea. The maximum‐likelihood (ML) tree obtained was consistent with the morphological and with previous molecular studies and showed that P. hebensis belongs to the order Endogenina, as a sister clade of the few taxa sequenced within this order. Including new genetic data to the Endogenina will allow building new hypothesis about the evolution of the most derived clade of suctorians.     

A hydrothermal vent mite (Halacaridae,Acari) with a new Corynophrya species (Suctoria,Ciliophora), description of the suctorian and its distribution on the halacarid mite

Copidognathus nautilei Bartsch, 1997, from a hydrothermal vent field of the Mid-Atlantic Ridge at about 13°N, 45°W and 4090 m depth, was infested with the suctorian Corynophrya abyssalis n. sp., with up to 58 epizoans per mite. The new suctorian has a sacciform body with seven longitudinal ribs, a compact macronucleus and up to 40 non-retractile tentacles. The budding is exogenous. The systematic position of the new species and the genus Corynophrya is discussed, as well as infestation rates and sites of suctorians on their halacarid hosts.     

Intestinal ciliate fauna of the Asian elephant from Gaziantep,Turkey and the description of Brevitentaculum antebum n. g., n. sp.

The aims of this investigation were to identify and quantify ciliates inhabiting the large intestine of Asian elephants living in Gaziantep Zoo, Turkey, and to describe a new suctorian genus and species. Species composition and distribution of intestinal ciliates voided in the feces of two Asian elephants were examined. Fifteen species of intestinal ciliates, representing 7 genera, were identified. One new suctorian genus and species, Brevitentaculum antebum n. g., n. sp., was described. This new species has two short truncated terminal projections, with two longitudinally lined bands located between the two projections, near the convex surface of the cell. Short clavate-like tentacles are in two fascicles near each base of terminal projections on the flattened surface of the body. Ciliate densities in the two fecal samples were 4.5 × 10⁴ mL⁻¹ and 10 × 10⁴ mL⁻¹.     

团头鲂寄生吸管虫一新种,双泡毛管虫的研究

描述了寄生在团头鲂(Megalobrama amblycephala)鳃上的一吸管虫新种,双泡毛管虫。活体无色透明至淡黄色,正面观为卵圆形至长椭圆形,稍扁平;侧面观为棒状或香肠状,常附着在鳃小片上。身体的表膜中有不明显的细小颗粒。吸管指状,一束,着生在虫体前端,一般有4—8根,最多达23根,收缩时其表面出现明显的螺旋纹8—11个。两个伸缩泡,交替地进行伸缩,彼此间隔约为10μm,位于吸管基部的胞质中。大核短杆状或椭圆形,核膜明显,染色质均匀。小核圆球形。成虫和幼虫没有固着柄,游泳幼虫的纤毛带宽6.0—7.0μm,由7—11行纤毛纹组成,无锥形的钻孔器。       

External parasite infestation depends on moult-frequency and age in Antarctic krill (<Emphasis Type="Italic">Euphausia superba</Emphasis>)

Levels of infestation by the suctorian Ephelota sp. were determined in Antarctic krill taken in the north-eastern region of the Scotia sea, close to the island of South Georgia. Individuals caught in summer between 2002 and 2004 were measured for body length, eye diameter, moult stage, sex, sexual maturity and number of suctorian parasites. All krill samples were found to contain at least two modal size-classes and the complete range of maturity- and moult stages. Sample analysis for the different characters identified moult stage as an important determinant of infestation by Ephelota sp., with 66% of those about to moult (pre-moult individuals) being infested compared with 0% of post-moult individuals. Multiple Correspondence Analysis also identified a strong link between age and degree of suctorian infestation with large-eyed (and hence old) males having very high numbers of suctorian bodies. Moulting is costly in terms of energy and vulnerability, but it is believed that krill moult at relatively high rates throughout their life to facilitate growth and “shrinkage”. Here, we demonstrate that the control of external parasitism is also a major advantage of moulting at high frequency. The capacity of krill to maintain a high moult rate decreases with age, leading to older krill enduring higher parasitic loads.     

Bacteria-like endobionts of the suctorian,Discophrya sp.

Summary Individuals ofDiscophrya sp. contain approximately 11,000 endobionts, interpreted as gram-positive bacteria. Treatment with the antibiotic rifampin resulted in destruction of the bacteria, but with an accompanying gigantism, loss of reproductive capacity and a restricted lifespan of the suctorian. Treatment with penicillin G resulted in a reduction of the bacterial population and gigantism. A subsequent increase in the number of bacteria coincided with a reduction in cell size of the suctorian. Copper ions were also found to destroy the bacteria. The possible existence of a symbiotic relationship between the two organisms is discussed.This work was supported by the J. S.Dunkerly Research Fellowship in Protozoology.     

Asterocheres crinoidicola n. sp., a copepod (Siphonostomatoida: Asterocheridae) parasitic on crinoids in Belize

A new species of siphonostomatoid copepod, Asterocheres crinoidicola, is parasitic on two closely related comasterid crinoids (Nemaster grandis and Davidaster rubiginosus) in Belize, Central America. An unusually long terminal prolongation of the third segment of the endopod of leg 1 distinguishes this species from all congeners. This is the first report of a copepod parasitic on a crinoid in the Caribbean.     

Ultrastructural and Other Observations Which Suggest Suctorian Affinities for the Taxonomically Enigmatic Ciliate Cyathodinium*

SYNOPSIS. Two species of the taxonomically enigmatic genus Cyathodinium, C. piriforme and C. cunhai, were studied in some detail at both light and electron microscopic levels. Data obtained strongly suggest suctorian affinities for the genus, since a number of structures or features are strikingly reminiscent of similar (if not homologous) structures recently discovered in ciliates belonging to the order Suctorida. Endosprits (suctorial tentacles?) of Cyathodinium show an arrangement of microtubules not unlike that known for several suctorians, especially Acineta and Tokophrya. Haptocysts or missile-like bodies, ca. 600 mμ long, have been observed within endosprits and free in the cytoplasm; again this is reminiscent of the complex organelles recently described from several suctorian groups. Mouthlessness, coupled with the presence of a ventral depression (functioning in gathering prey at distal ends of endosprits?) and the presence of food vacuoles in the cytoplasm, further support a suctorian mode of feeding. Finally, stages in the curious life cycle of Cyathodinium suggest neoteny and a basic similarity to endogenous budding processes in certain suctorians.     

Deep-sea asellote isopods of the north-east Atlantic: the family Dendrotionidae and some new ectoparasitic copepods

A new species of Dendromunna and two new species of Dendrotion are described from abundant material collected in the Rockall Trough region of the north-east Atlantic. The taxonomy of the little known benthic deep-sea asellote isopod family Dendrotionidae is reviewed and keys provided for genera and species. Also diagnosed and described are two new species belonging to a new genus of siphonostomatoid copepod found as ectoparasites on the walking legs of the new Dendromunna. The new parasites belong in the Rhizorhina group of genera within the family Nicothoidae.     

Infraciliature, Morphogenesis and Life Cycle of Endosphaera terebrans (Suctoria, Tokophridae)

The morphology, infraciliature, and life cycle of Endosphaera terebrans , a suctorian endocommensal of peritrichs, have been studied with the aid of silver impregnation.
The life cycle of Endosphaera terebrans begins with infection of the host cell by a small larva. The swarmer has a pointed needle-like cellular projection and two rings of cilia. The swarmer penetrates the peritrich, loses the cilia, and then matures into an adult. The infraciliature of the adult form has four rows of barren kinetosomes that lack kinetodesmal fibers. By endogenous budding, a migratory larva is produced that leaves the host cell through the peristomial disc and that can infect other peritrichs.     

A new genus and two new species of Choniostomatidae (Copepoda) parasitic on two deep sea isopods

The systematic position of the little-deformed parasitic copepod family Nicothoidae to the much deformed family Choniostomatidae has been disputed for many years. The new genus Diexanthema gen. nov., based on Diexanthema desistoma sp. nov. and Diexanthema bathydiaita sp. nov. discovered on two deep-sea asellote isopod species, clearly links the family Nicothoidae (via male Diexanthema) to the family Choniostomatidae (via female Diexanthema). Based upon the extreme sexual dimorphism of this new genus, it is suggested that the family Nicothoidae be dissolved and its members placed within the family Choniostomatidae. It is concluded that the differences seen between these two parasitic groups is probably due more to host adaptations than reflecting any phylogenetic trend that is evolutionarily significant. It is felt that the deep-sea environment may serve as a refugium for archaic copepod forms which may possibly offer additional clues and insights into the phylogeny of the parasitic copepoda.
This investigation suggests that the life history and parasite/host relationships of Diexanthema desistoma are quite complicated and well geared to the life history of its isopod host, Chelator insignis.     

Caligus tunisiensis n. sp. (Copepoda: Caligidae) parasitic on the painted comber Serranus scriba (L.) (Perciformes: Serranidae) from the Mediterranean Sea,off the Tunisian coast

Systematic Parasitology - A new species of parasitic copepod, Caligus tunisiensis n. sp. (Caligidae), is described based on two female specimens collected from the gills of the painted comber,...     

Evolution of bioluminescence in marine planktonic copepods

Copepods are the dominant taxa in zooplankton communities of the ocean worldwide. Although bioluminescence of certain copepods has been known for more than a 100 years, there is very limited information about the structure and evolutionary history of copepod luciferase genes. Here, we report the cDNA sequences of 11 copepod luciferases isolated from the superfamily Augaptiloidea in the order Calanoida. Highly conserved amino acid residues in two similar repeat sequences were confirmed by the multiple alignment of all known copepod luciferases. Copepod luciferases were classified into two groups of Metridinidae and Heterorhabdidae/Lucicutiidae families based on phylogenetic analyses, with confirmation of the interrelationships within the Calanoida using 18S ribosomal DNA sequences. The large diversity in the specific activity of planktonic homogenates and copepod luciferases that we were able to express in mammalian cultured cells illustrates the importance of bioluminescence as a protective function against predators. We also discuss the relationship between the evolution of copepod bioluminescence and the aspects of their ecological characteristics, such as swimming activity and vertical habitat.     

Hydrodynamic interaction between two copepods: a numerical study

Numerical simulations were carried out to compute the flow fieldaround two tethered, stationary or swimming model-copepods withvaried separation distances between them and for different relativebody positions and orientations. Based on each simulated flowfield, the power expended by each copepod in generating theflow field and volumetric flux through the capture area of eachcopepod were calculated. The geometry of the flow field aroundeach copepod was visualized by tracking fluid particles to constructstream tubes. The hydrodynamic force on each copepod was calculated.Also, velocity magnitudes and deformation rates were calculatedalong a line just above the antennules of each copepod. Allthe results were compared to the counterpart results for a solitarycopepod (stationary or swimming) to evaluate the hydrodynamicinteraction between the two copepods. The calculations of thepower and volumetric flux show that no energetic benefits areavailable for two copepods in close proximity. The results ofthe stream tube and force calculations show that when two copepodsare in close proximity, the hydrodynamic interaction betweenthem distorts the geometry of the flow field around each copepodand changes the hydrodynamic force on each copepod. Two beneficialroles of the hydrodynamic interactions are suggested for copepodswarms: (1) to maintain the integrity of the swarms and (2)to separate the swarming members with large nearest neighbourdistances (usually more than five body lengths). To preventstrong hydrodynamic interactions, copepods in swarms have toavoid positions of strong interactions, such as those directlyabove or below their neighbours. The results of the velocitymagnitudes and deformation rates demonstrate that the hydrodynamicinteraction between two copepods generates the hydrodynamicsignals detectable by the setae on each copepod's antennules.Based on the threshold of Yen et al. (1992), the results showthat the detection distance between two copepods of comparablesize is about two to five body lengths. Copepods may employa simple form of pattern recognition to detect the distance,speed and direction of an approaching copepod of comparablesize.     

Ultrastructural Features of Allantosoma intestinalis,a Suctorian Ciliate Isolated from the Large Intestine of the Horse1

ABSTRACT. Allantosoma intestinalis, a suctorian ciliate isolated from the intestine of the horse, was studied utilizing light and electron optical methods. These small sausage-shaped organisms have a varying number of tentacles (between one and 12) located at each extremity of the body. The microtubular axoneme of each tentacle in cross-section consists of two files of microtubules arranged in a daisy-like configuration. Haptocysts occur in the tentacle shaft, abutted to the plasma membrane of the knob of the tentacle, and in the cell body. The haptocysts are bottle-shaped, with prominent annular striations around their midportion. The cell is covered by three membranes, an outer plasma membrane, an outer alveolar, and an inner alveolar membrane. A thin epiplasmic layer is found beneath the inner alveolar membrane, and a single row of microtubules underlies the epiplasm. The subpellicular microtubules are arranged parallel to each other forming a corset around the cell along the long axis: such a system is not characteristic of suctorians. A field of diminutive kinetosomes (each 180 nm long, max. of 15 per field), lacking cilia, was found below the cortex. The function of these prokinetosomes is unknown. A ciliated swarmer has not been observed, only the nonciliated adult. The characteristics of Allantosoma are compared with those of other suctorian genera.     

Doridicola indistinctus n. sp. (Copepoda: Poecilostomatoida: Rhynchomolgidae) associated with the soft coral Gersemia fruticosa Sars (Octocorallia: Alcyonacea: Nephtheidae) from the White Sea

A new species of poecilostomatoid copepod, Doridicola indistinctus n. sp. (Rhynchomolgidae), is described from specimens found in association with the soft coral Gersemia fruticosa Sars (Alcyonacea: Nephtheidae), collected from the White Sea. The new species is distinguished from its congeners by the combination of the following features in the female: (i) antenna tipped, with two subequal large claws which are about as long as the segment bearing them; (ii) two naked, extremely unequal setae on the middle segment of the maxilliped, the short, medial seta less than half-length of the outer seta; and (iii) free segment of leg 5 bears the basal swelling and is ornamented with spinules on the outer surface. This is the first report of a copepod occurring in symbiosis with nephtheid corals from the Arctic Zone. It also constitutes the northernmost record for a species of Doridicola Leydig, 1853, which is the largest genus of the Rhynchomolgidae Burmeister, 1835 comprising 52 species, including the present new species.