Plumatella emarginata

Proposal for common name: Robust bryozoan or moss animal

Classification

Class	Family	Genus	Species	First described by
Phylactolaemata	Plumatellidae	Plumatella	P. emarginata	Allman 1844

Synonyms

The following synonyms have been used to indicate Plumatella emarginata:

Plumatella emarginata (Allman 1844)
Plumatella jugalis (Allman 1844)
Plumatella allmani (Hanckock 1850)
Plumatella diffusa (Leidy 1851)
Alyconella benedeni (Allman 1851)
Plumatella aplinii (MacGillivray (1860)
Plumatella repens (Jullien 1885)
Plumatella princeps var. emarginata (Kraepelin 1887)
Plumatella princeps var. muscosa (Kraepelin 1887)
Plumatella princeps var. spongiosa (Kraepelin 1887)
Plumatella repens var. emarginata (Vangel 1894)
Plumatella repens var. benedeni (Vangel 1894)
Plumatella emarginata var. emarginata (Hartmeyer 1909)
Plumatella spongiosa (Hartmeyer 1909)
Plumatella repens var. jugalis (Rogerick & van der Schalie 1950)

Description

Also see the generic class and genus description in the classification page.
A combination of literature has been used to create this description.

General	Plumatella emarginata is easily overlooked as at first glance they seem small brownish growths. Also there is confusion with Fredericella sultana, that is less robustly build. Colonies are often branching, sometimes lawn like or compact / ball shaped Cystids mostly have a keel Cystids are encrusted in small grains of sand Cystids are partly adherent and A contrasting transparent region encircles the zooid tip and tapers away on the frontal surface of the zooid to form a V-shaped 'neckline' All these properties can be absent so a definite identification can only be done by studying the statoblasts. The emargination (V-shaped neckline), that has defined the name for this species, can be absent and is often difficult to discern. The zooids often have a dorsal keel and the colonies are almost completely encrusting (crawl across the substrate)
Color	Description not found in literature
Tentacle crown	Horseshoe shaped tentacle crown with 30 to 60 tentacles.
Size	One zooid is 2 mm long A colony maximum ?? cm in diameter
Statoblasts	The floating statoblasts (floatoblasts) are twice as long as broad. The borders are more or les parallel. The floating band extends significantly beyond the capsule. They are often flattened at the ends (pols) so the circumference is almost square. The capsule covers the annulus dorsally more than ventrally. The annulus has the same breadth all around The sinking statoblasts (sessoblasts) are attached to the substrate, broad-oval, with rudimentary floating ring, but without recognizable 'kammerung' (chambers) There are multiple statoblasts per zooid
Conditions	In clear waters
Distribution	Distribution not found in literature
Additional	No information

Relevant literature

To be completed

[Mundy] - A key to the British and European Freshwater Bryozoans
[Wood II] - A new key to the freshwater bryozoans of Britain, Ireland and Continental Europe

My observations

I have found P. emarginata only in one place so far
In my experience P. emarginata can be found most easily in the fall when the colonies are better developed.
When the water temperature rises above about 16° Celsius the colonies start developing
When the water temperature drops below 12-10° Celsius P. emarginata will die
P. emarginata looks a lot like P. fruticosa and F. sultana, but is more robust then P. fruticosa and has a larger more complex polyp then F. sultana
P. emarginata is the only species with adherent branches of these three
I found them almost hidden between rocks between F. sultana and P. fruticosa (as well as P. articulata)
In my opinion P. emarginata has the same need as F. sultana, P. fruticosa and P. articulata to seek shelter from settling silt.