title: First freshwater coralline alga and the role of local features in a major biome transition.
abstract: Coralline red algae are significant components of sea bottom and up to now considered as exclusively marine species. Here we present the first coralline alga from a freshwater environment, found in the Cetina River (Adriatic Sea watershed). The alga is fully adapted to freshwater, as attested by reproductive structures, sporelings, and an inability to survive brackish conditions. Morphological and molecular phylogenetic analyses reveal the species belongs to Pneophyllum and is described as P. cetinaensis sp. nov. The marine-freshwater transition most probably occurred during the last glaciation. The brackish-water ancestor was preadapted to osmotic stress and rapid changes in water salinity and temperature. The particular characteristics of the karst Cetina River, such as hard water enriched with dissolved calcium carbonate and a pH similar to the marine environment, favoured colonization of the river by a marine species. The upstream advance and dispersal is facilitated by exceptionally pronounced zoochory by freshwater gastropods. Pneophyllum cetinaensis defies the paradigm of Corallinales as an exclusively marine group.
authors.affiliation: Institute of Oceanography and Fisheries, 21000 Split, Croatia.
authors.forename: A
authors.initials: A
authors.lastname: Žuljević
authors.affiliation: Department of Life Science, University of Trieste, 34127 Trieste, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Kaleb
authors.affiliation: BIOCOST Research Group, Departamento de Bioloxía Animal, Bioloxía Vexetal e Ecoloxía, Facultade de Ciencias, Universidade da Coruña, 15071, A Coruña, Spain.
authors.forename: V
authors.initials: V
authors.lastname: Peña
authors.affiliation: Institute of Oceanography and Fisheries, 21000 Split, Croatia.
authors.forename: M
authors.initials: M
authors.lastname: Despalatović
authors.affiliation: Institute of Oceanography and Fisheries, 21000 Split, Croatia.
authors.forename: I
authors.initials: I
authors.lastname: Cvitković
authors.affiliation: Research Group Phycology, Ghent University, 9000 Ghent, Belgium.
authors.forename: O
authors.initials: O
authors.lastname: De Clerck
authors.affiliation: Equipe Exploration, Espèces et Evolution, Institut de Systématique, Evolution, Biodiversité, UMR 7205 ISYEB CNRS, MNHN, UPMC, EPHE, Muséum national d'Histoire naturelle (MNHN), Sorbonne Universités, F-75005, Paris, France.
authors.forename: L
authors.initials: L
authors.lastname: Le Gall
authors.affiliation: Department of Life Science, University of Trieste, 34127 Trieste, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Falace
authors.affiliation: Department of Life Science, University of Trieste, 34127 Trieste, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Vita
authors.affiliation: Departamento de Estratigrafía y Paleontología, Universidad de Granada, Campus Fuentenueva, 18002, Granada, Spain.
authors.forename: Juan C
authors.initials: JC
authors.lastname: Braga
authors.affiliation: Institute of Oceanography and Fisheries, 21000 Split, Croatia.
authors.forename: B
authors.initials: B
authors.lastname: Antolić
mesh_terms: D017753:Ecosystem; D005618:Fresh Water; D005798:Genes, Bacterial; D010802:Phylogeny; D000461:Rhodophyta / Q000145:classification / Q000235:genetics / Q000648:ultrastructure; D013171:Spores, Bacterial