New occurrence and distribution of Nitella hyalina (DC.) Agardh (Characeae) and the first report on Nitelletum hyalinae Corillion 1957, in Croatia

Abstract

In 2011, a new population of the stonewort Nitella hyalina was found on the island of Pag, in a pond between Novalja and Lun, near the cove of Dubac. At the littoral, unshielded zone of this unnamed, small shallow lake Nitella hyalina forms large monodominant patches or grows together with Potamogeton trichoides Cham. et Schl. and P. nodosus Poir. We identified these stands as the species’ poor association of Nitelletum hyalinae Corillion 1957, a new vegetation type of Croatia. Nitella hyalina is sparse in Europe and rather rare on the Balkan Peninsula. It was previously detected only in two places in Croatia. Considering its severely fragmented distribution and the fact that at present it is known to exist at only three locations, Nitella hyalina should be treated as an endangered (EN) taxon among the Charophytes of Croatia.

Keywords

• Aquatic vegetation
• endangered
• Nitellion flexilis
• Pag island
• stonewort