Ultrastructural observations of the protonephridia of Polymerurus nodicaudus (Gastrotricha: Paucitubulatina)
Article first published online: 22 DEC 2010
© 2010 The Authors. Acta Zoologica © 2010 The Royal Swedish Academy of Sciences
Volume 93, Issue 1, pages 115–124, January 2012
How to Cite
Kieneke, A. and Hochberg, R. (2012), Ultrastructural observations of the protonephridia of Polymerurus nodicaudus (Gastrotricha: Paucitubulatina). Acta Zoologica, 93: 115–124. doi: 10.1111/j.1463-6395.2010.00494.x
- Issue published online: 13 DEC 2011
- Article first published online: 22 DEC 2010
- Accepted for publication: 23 November 2010
- evolutionary scenario;
Kieneke, A. and Hochberg, R. 2012. Ultrastructural observations of the protonephridia of Polymerurus nodicaudus (Gastrotricha: Paucitubulatina). —Acta Zoologica (Stockholm) 93: 115–124.
We studied different regions of the protonephridia of the limnic gastrotrich Polymerurus nodicaudus by means of light and electron microscopy to determine how freshwater species might differ from their marine relatives. Microscopic and ultrastructural characters are in accordance with another limnic species of Paucitubulatina, Chaetonotus maximus, whose protonephridial system has been previously reconstructed. Shared protonephridial characters of both species include the presence of highly elongate terminal organ cilia, microvilli, and the canal cell lumen as well as the presence of a conspicuous anterior loop of the protonephridial lumen. These features are not present in representatives of earlier, marine, paucitubulatan lineages (i.e., Xenotrichulidae) and so are assessed as evolutionary novelties that were likely important for the successful colonization of the freshwater environment.