Morphology of the Orthonectid Rhopalura ophiocomae

Kozloff, Eugene N.

doi:10.2307/3277368

Cited by 49 publications

(32 citation statements)

References 6 publications

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“…Therefore we propose that the Orthonectida have the apomorphic pattern in the ciliated cells like other multiciliated teguments. Kozloff (1969) found the kinetosomes in R. ophiocomae to have prekinetosomal bodies, which are absent in I. variabili; he later (Kozloff 1971) studied Ciliocincta sabellariae Kozloff, 1971 and found the structure of the kinetosomes and the rootlets to be the same as in R. ophiocomae, but C. sabellariae was not studied in as much detail as R. ophiocomae, so it cannot be excluded that some features were overlooked. In this species, cilia are also situated in pits as in I. variabili, but there is only one cross-striated rootlet going anteriorly and parallel to the surface of the cell, as opposed to the two rootlets of I. variabili.…”

Section: Resultsmentioning

confidence: 99%

“…The same feature could be used in the studies of phylogenetic relations within one taxon, for example, such as Plathelminthes (Ehlers 1985) or Xenoturbellida (Franzén and Afzelius 1987). The studies of general morphology of Orthonectida by Kozloff (1969) and Slyusarev (1994) briefly mentioned rootlets but did not treat them in any detail. In order to test the assumption that Orthonectida are derived members of the Annelida or at least closely related to them, we have provided a detailed description of the structure of the ciliated cells and the ciliary basal structures of I. variabili in this study.…”

Section: Introductionmentioning

confidence: 99%

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Fine structure of the ciliated cells and ciliary rootlets of Intoshia variabili (Orthonectida)

Slyusarev

Kristensen

2003

Zoomorphology

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The body of the Intoshia variabili (Orthonectida) is covered by a layer of alternating rings of flattened ciliated and non-ciliated cells, covered by a thin 0.25-to 0.30-µm cuticular layer. Ciliated cells bear rows of cilia, with five to seven cilia in each row. The kinetosome of each cilium is situated in a small pit and bears two identical cross-striated rootlets oriented along the longitudinal axis of the body and parallel to the cell surface. Two types of cell contacts are present between these cells, spot desmosomes and tight junctions. Two fibrous bands, an anterior and a posterior one, both running parallel to the cell surface, are always present in the apical part of both the ciliated and the non-ciliated cells. These fibrous bands are not only attached to the desmosomes between the cells within a ring but also connect them, traversing the cell. Thus, two fibrous rings are formed within every ring of ciliated and non-ciliated cells. The rootlets of the cilia closest to the fibrous band are connected with the bands. These bands of filaments and the associated rootlets form a unique structure for the orthonectids. The phylogenetic relationships of Orthonectida are considered on the basis of this new information. The hypothesis that Orthonectida are derived Annelida or at least derived Trochozoa has gained support based mainly on the new ultrastructural data, such as the true cuticle and fibrous bands in the epithelial cells consisting of ciliated and non-ciliated cells.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Fine structure of the ciliated cells and ciliary rootlets of Intoshia variabili (Orthonectida)

Slyusarev

Kristensen

2003

Zoomorphology

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“…The mean intensity of infection (I) in infected hosts was 1.389 parasites per brittlestar while the mean intensity of parasitization for the whole sample () was 0.286 parasites per host. A low level of infection (prevalence between 1% and 2%) with the orthonectid mesozoan parasite Rhopalura ophiocomae (see Kozloff, 1969) was also present in the Amphipholis population.…”

Section: Disc Size Classes (Mm)mentioning

confidence: 97%

Parachordeumium amphiurae: a cuckoo copepod?

Whitfield

Emson

1988

Hydrobiologia

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The impact of the endoparasitic copepod Parachordeumium amphiurae ( = Amphiurophilus amphiurae of Goudey-Perriere, 1979) on a host population of the brooding, hermaphroditic ophiuroid Amphipholis squamata in intertidal rock pools in South Devon, UK was assessed. In August 1986 the parasite prevalence was 20.6% and the mean population intensity of infection 0.286 parasites per brittlestar. Female parasites inhabited the genital bursae of hosts and most were found in hosts that were potentially reproductively active. In such hosts brooding capacity was reduced by copepod parasitism. Infected brittlestars showed a reduction in numbers of brooded developmental stages when compared with uninfected hosts of similar size (but the mean size of brooded development stages was not affected). For the population sampled, the overall reduction in brooding capacity was about 44%. The association between Amphipholis and Parachordeumium was compared with normal brood parasitism.

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“…All orthonectids are parasites, utilizing a wide variety of marine invertebrates as hosts, including turbellarians, nemertines, annelids, molluscs, echinoderms, and ascidians. Only 21 species of orthonectids have been correctly described (Kozloff 1992).…”

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confidence: 99%

Sperm structure of Rhopalura littoralis (Orthonectida)

Slyusarev

Ferraguti

2002

Invertebrate Biology

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Abstract. We present here a description of the spermatozoon of Rhopalura littoralis, the first fine‐structural study of an orthonectid sperm. The spermatozoon contains a slightly elongate nucleus and two centrioles orientated along the longitudinal axis of the sperm. The proximal centriole bears one rootlet. A single mitochondrion is present in the mid‐piece region. An acrosome is absent. The sperm tail is a simple flagellum with 9+2 structure. We consider the orthonectan spermatozoon to be closer in structure to those of Porifera, Cnidaria, and Annelida, than to Aschelminthes and Platyhelminthes, to which orthonectids have previously been allied.

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Morphology of the Orthonectid Rhopalura ophiocomae

Cited by 49 publications

References 6 publications

Fine structure of the ciliated cells and ciliary rootlets of Intoshia variabili (Orthonectida)

Fine structure of the ciliated cells and ciliary rootlets of Intoshia variabili (Orthonectida)

Parachordeumium amphiurae: a cuckoo copepod?

Sperm structure of Rhopalura littoralis (Orthonectida)

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