Ultrastructure of the protonephridial system in Neodasys chaetonotoideus (Gastrotricha: Chaetonotida) and in the ground pattern of Gastrotricha

The taxon Neodasys has a basal position within Gastrotricha. This makes it very interesting for phylogenetic considerations in this group. To complete the reconstruction of the nephridial system in the stem species of Gastrotricha started earlier, we have studied the whole protonephridial system of...

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Bibliographic Details
Published in:Journal of morphology (1931) 2007-07, Vol.268 (7), p.602-613
Main Authors: Kieneke, Alexander, Arbizu, Pedro Martínez, Ahlrichs, Wilko H.
Format: Article
Language:English
Subjects:
Animals
Bilateria
Biological Evolution
Gastrotricha
Helminths - anatomy & histology
Helminths - classification
Helminths - ultrastructure
Microscopy, Electron, Transmission
Models, Anatomic
Neodasys
phylogenetic implications
protonephridia
TEM
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Summary:The taxon Neodasys has a basal position within Gastrotricha. This makes it very interesting for phylogenetic considerations in this group. To complete the reconstruction of the nephridial system in the stem species of Gastrotricha started earlier, we have studied the whole protonephridial system of Neodasys chaetonotoideus by means of complete sets of ultrathin sections and TEM. In many characters, protonephridia of N. chaetonotoideus resemble those of macrodasyidan gastrotrich species. For example, each of the six protonephridia, arranged in three pairs, consists of three distinct cells that constitute the continuous protonephridial lumen. Especially, the terminal cell of the protonephridia of N. chaetonotoideus shows a striking pattern: The perforation of the filter region is a meandering cleft that is continuous with the seam of the enfolded lumen of that cell. With the results presented here and that of former TEM studies, we give a comprehensive idea of the excretory organs in the ground pattern of Gastrotricha. Moreover, we can elaborate on the hypothesized protonephridial system in the stem species of Bilateria. We suggest that a meandering filtration cleft is a feature of the ground pattern of the Bilateria. J. Morphol., 2007. © 2007 Wiley‐Liss, Inc.
ISSN:0362-2525
1097-4687
DOI:10.1002/jmor.10536