Plumatella geimermassardi (Wood & Okamura 2004)

Verder in Nederlands

  1. More information
  2. Photos
  3. Microscope photos and videos
  4. Statoblasts

Proposal for common name: ?? bryozoan or moss animal

Plumatella geimermassardi


Class Family Genus Species Described by
Phylactolaemata Plumatellidae Plumatella P. geimermassardi Wood & Okamura 2003


The following synonyms have been used to indicate Plumatella geimermassardi:

  1. None


Also see the generic class and genus description in the classification page.
For the description a combination of literature is used. In this case especially [Wood 2003] and [Wood 2005].

General Colonies are formed as branching, closely aligned and sometimes fusing tubules of uniform diameter, that attach fully to the substrate. Free hanging branches may form if the substrate is limited and the colony crowded.
The zooid wall is smooth and transparent, sometimes lightly covered with external particles. A faint raphe (keel) may form, but is usually lacking. In older colonies the wall becomes darker and stiffer but still is transparent.
The colony tubules have stout reinforcing rings with a hole in the center that reduces the inner zooecial diameter by as much as 80% .
Color Transparent, chitinous; darker in older colonies
Tentacle crown Tentacle crown is horseshoe shaped with 30 - 40 tentacles.
Dimensions The zooid tubule has a diameter of 250 - 450 m
Statoblasts The floating statoblasts (floatoblasts) are relatively small and broad. Lateral symmetry is common. The two halves are comparable in frontal view, each with a large fenestra and an annulus. The floatoblast has low, weakly formed tubercules that become more indistinct towards the center.
The sinking statoblasts (sessoblasts) are fully covered with well defined tubercules along the frontal half and along both sides of the annulus
There are multiple statoblasts per zooid.
Environment P. geimermassardi is found in still water, such as lakes and ponds.
Distribution Known from Ireland, England, Belgium, South Norway, Northern Germany and Italy
It can be assumed the species occurs in large parts of Europe. The eastern border is still unclear.
In addition Plumatella geimermassardi is a newly recognized and described species
It is clear that the species lives in the region for a long time. The oldest material goes back to 1845
The species is rare

Relevant literature

  1. [Wood 2003] - Plumatella geimermassardi, a newly recognized freshwater bryozoan from Britain, Ireland and continental Europe
  2. [Wood 2005] - A new key to the freshwater bryozoans of Britain, Ireland and Continental Europe

My observations

  1. I have found P. geimermassardi on the concrete walls of a tunnel for water under a road - for the stream 'de Drentse Aa'. The walls were covered in many places over a length of about 6 meters, except for near the entrances.
  2. I had seen this bryozoan on this place in previous years, but thought it to be P. fungosa.
    P. fungosa and P. geimermassardi both have a similar sized lophophore (smaller than P. repens) and a similar greyish-white color (where P. repens is more brownish).
  3. only after I took a sample home and looked through a microscope it became clear it is P. geimermassardi and not P. fungosa.
    The zooids are not tightly packed and the colonies look messy as compared to P. fungosa. In comparison to P. repens the latter's zooids and tubes are larger and more brownish.
  4. I assume now that P. fungosa always grows in a compact form, while P. geimermassardi has colony forms that are more comparable to P. repens, more messy with tight packed zooids in one place and creeping extensions in another.
  5. I find this bryozoan in this location excluively a few weeks in May/June. The water temperature is 15-17 degrees Celcius and it coincides with the spring algae bloom. It appears there is only one generation in a year. I will monitor the location closely.
  6. There is more to be told about the habitat: it is a concrete tube (rectangular) under a road that is always dark (except for the ends) and allows a standing to slow moving stream to pass under the road into a lake. The water is fairly eutrophe with a visibility of 30-40 cm at its best.
  7. Except for P. geimermassardi i also see freshwater sponges and here and there F. sultana.
  8. Last year P. geimermassardi was found (recognized) for the first time in the Netherlands. It was found on a piece of plastic garbage in a fairly eutrophous lake in the southe of the Netherlands. It seems P. geimermassardi has a different preference for substrate than P. fungosa and P. repens (who prefer wood and stone). Worthwhile to keep an eye on.
  9. Closely associated with the P. geimermassardi colony i found a few other species: Assel assel, a bristleworm and a few nematodes (species unkownn to me). I also found a Cyclops sp. who got probably stuck there by accident as there were many free swimming in the surrounding water.