Three‐dimensional reconstruction of the musculature of various life cycle stages of the cycliophoran Symbion americanus

  title={Three‐dimensional reconstruction of the musculature of various life cycle stages of the cycliophoran Symbion americanus},
  author={Ricardo Cardoso Neves and Reinhardt M{\o}bjerg Kristensen and Andreas Wanninger},
  journal={Journal of Morphology},
Cycliophora is a very recently described phylum of acoelomate metazoans with a complex life cycle and a phylogenetic position that has been under debate ever since its discovery in 1995. Symbion americanus, which lives attached to the mouthparts of the American lobster, Homarus americanus, represents the second species described for the phylum. Aiming to increase the morphological knowledge about this cryptic clade, the present study describes the muscle arrangement of the feeding stage, the… 

Comparative myoanatomy of cycliophoran life cycle stages

New details on the muscular anatomy of the feeding stage, the attached Prometheus larva, the dwarf male, and the female of one of the two hitherto described species, Symbion pandora are added.

External morphology of the cycliophoran dwarf male: a comparative study of Symbion pandora and S. americanus

In both Symbion species, anterior and ventral ciliated fields, as well as paired lateral sensorial organs, were identified, thus confirming previous observations, however, new details are described herein such as the penial pouch that encloses the penis.

Detailed reconstruction of the musculature in Limnognathia maerski (Micrognathozoa) and comparison with other Gnathifera

This study reveals a complex body wall musculature, comprising six pairs of main longitudinal muscles and 13 pairs of trunk dorso-ventral muscles, and suggests a closer functional resemblance to the jaw organization in Rotifera.

Ultrastructure and morphology of the cycliophoran female

The morphology and ultrastructure of the free and fully mature female of Cycliophora is described now for the first time and this life cycle stage is compared with that fromother phyla, suggested as phylogenetically close.

Shaping the Things to Come: Ontogeny of Lophotrochozoan Neuromuscular Systems and the Tetraneuralia Concept

Overall, formation of the lophotrochozoan neuromuscular bodyplan appears as a highly dynamic process on both the ontogenetic and the evolutionary timescales, highlighting the importance of insights into these processes for reconstructing ancestral bodyplan features and phylogenetic relationships.

Development of the annelid axochord: Insights into notochord evolution

Ancestral state reconstruction suggests that contractile mesodermal midline cells existed in bilaterian ancestors and it is proposed that these cells, via vacuolization and stiffening, gave rise to the chordate notochord.

Musculature of two bdelloid rotifers, Adineta ricciae and Macrotrachela quadricornifera: organization in a functional and evolutionary perspective

The musculature of two bdelloid species, Adineta ricciae and Macrotrachela quadricornifera, was illustrated, and their organization was compared with other rotifer taxa to generate possible hypotheses of evolutionary relationships among Rotifera.

Microanatomy and Development of the Dwarf Male of Symbion pandora (Phylum Cycliophora): New Insights from Ultrastructural Investigation Based on Serial Section Electron Microscopy

Comparison of three cycliophoran dwarf males at different developmental stages reveals unprecedented insight into the striking morphological and developmental differences that characterize these highly miniaturized male stages both at the level of body organization and at thelevel of cellular ultrastructure.

Musculature in polychaetes: comparison of Myrianida prolifera (Syllidae) and Sphaerodoropsis sp. (Sphaerodoridae)

The results do not support a sister-group relationship of Syllidae and Sphaerodoridae, and Myrianida prolifera is yet another example in the list of polychaetes lacking typical circular muscles in the body wall.

Did the notochord evolve from an ancient axial muscle? The axochord hypothesis

It is proposed that the notochord evolved by modification of a ventromedian muscle followed by the assembly of an axial complex supporting swimming in vertebrate ancestors.



The chordoid larva of Symbion pandora (Cycliophora) is a modified trochophore

  • P. Funch
  • Biology
    Journal of morphology
  • 1996
Important morphological observations indicate that, despite some dissimilarities, the chordoid larva of the cycliophoran species, Cycliophora among protostomians is a modified trochophore.

Myo‐anatomy of juvenile and adult loxosomatid Entoprocta and the use of muscular body plans for phylogenetic inferences

Variations in the muscular anatomy provide useful characters for systematic analyses on species as well as phylum level and thus allow significant insight regarding metazoan body plan evolution, but the phenomenon of phenotypic plasticity and its consequences for phylogenetic interpretations must be carefully considered.

Functional morphology of the muscles in Philodina sp. (Rotifera: Bdelloidea)

Whole-mounts of Philodina sp., a bdelloid rotifer, were stained with fluorescent-labeled phalloidin to visualize the musculature. Several different muscle types were identified including incomplete

Immunocytochemistry of the nervous system and the musculature of the chordoid larva of Symbion pandora (Cycliophora)

The anatomy of the nervous system and the musculature of the chordoid larva was investigated by applying fluorescence‐coupled antibodies against the neurotransmitters serotonin and FMRFamide, as well as FITC‐ coupled phalloidin to label filamentous F‐actin, in combination with confocal laser scanning microscopy.

Development of the musculature in the limpet Patella (Mollusca, Patellogastropoda)

Because the adult shell muscles are entirely independent from the various larval muscular systems, several current hypotheses on the ontogeny and phylogeny of the early gastropod muscle system have to be reconsidered.

Muscle development in Antalis entalis (Mollusca, Scaphopoda) and its significance for scaphopod relationships

The existence of a distinct pair of cephalic retractors, which is also found in basal gastropods and cEPhalopods, as well as new data on scaphopod shell morphogenesis and recent cladistic analyses, indicate that the Scaphopoda may be more closely related to the Gastropoda and Cephalopoda than to the Bivalvia.

Nervous and muscle system development in Phascolion strombus (Sipuncula)

Although no indications for cryptic segmentation were found, certain neuro-developmental traits in Phascolion resemble the conditions found in polychaetes and myzostomids and support a close relationship of Sipuncula and Annelida.

Comparative morphology of the body wall in flatworms (Platyhelminthes)

The neodermis can be seen as a special adaptation of a developmental mechanism common to all platyhelminths, in which epidermal growth and renewal are accomplished by replacement cells originating beneath the body wall.

External Morphology and Muscle Arrangement of Brachionus urceolaris, Floscularia ringens, Hexarthra mira and Notommata glyphura (Rotifera, Monogononta)

The study showed that using both CLSM and SEM provides better resolution of the anatomy and external morphology of rotifers than using one of these techniques alone, which can facilitate better understanding of the complicated anatomy of these animals.