[RPB]

Is this Riccardia chamedrifolia?

It has the same structure as Riccia fluitans, but this one is darker green en does not float.

 

[Cavan Allen]

That is Riccia fluitans. For reasons that aren't quite understood, it sometimes changes over into the darker green sinking form.

http://www.tropica.com/article.asp?type=aquaristic&id=468

About half way down there.

 

[RPB]

Oke, thank you. Never seen before.