Pneophyllum cetinaensis is the only known species of freshwater coralline algae endemic to Croatia.

[2] Its ancestor lived in brackish water, and was already adapted to osmotic stress and rapid changes in water salinity and temperature.

[2][3] P. cetinaensis differs from other coralline red algae species in that it forms extensive and conspicuous crusts thickened with multi-layered flattened or curved branches.

It also has a pore canal of simple conceptacles which are not surrounded by specialised cells.

It also the only known coralline red algae species which confined to a freshwater stream as opposed to saltwater marine environment.