On findings of the red alga Gaillona rosea (Roth) Athanasiadis (Rhodophyta) in the Russian part of the South-Eastern Baltic

Information on the first findings of Gaillona rosea (Roth) Athanasiadis 2016:814 (Aglaothamnion roseum (Roth) Maggs & L’Hardy-Halos 1933:522) in the Russian part of the South-Eastern Baltic is given. Samples of algae in the Russian part of the South-Eastern Baltic along the coast of the Kaliningrad region at depths of 1–15 m were collected by diving method on the north coast of the Sambian Peninsula near Cape Taran and Cape Gvardeysky at the stations confined to hard ground. First samples of G. rosea collected from drifting mats of perennial algae Furcellaria lumbricalis and Polysiphonia fucoides were first registered along the west and north coast of the Sambian Peninsula (Cape Taran) at depths of 1.5–7 m in autumn 2015. The finding of the species in 2015 on the west coast of the Sambian Peninsula is the first registration for the coast of the Gdansk Bay. In July 2016, the species was found in samples at Cape Taran at a depth of 0.5 m. The length of the thalli does not exceed 3 cm. The species was registered with F. lumbricalis and P. fucoides, both in attached communities and in drifting mats. G. rosea is quite common in the Baltic Sea, with the exception of the Gdansk Bay and the northernmost part of the Baltic Sea, where the salinity is low. There is no data available on the abundance of the species in the adjacent Lithuanian waters. The species is rarely registered in the Russian part of the South-Eastern Baltic, and therefore G. rosea is rare in the entire South-Eastern Baltic Sea.