New terrestrial cyanobacterial species from the vicinity of the CIIMAR building on the Portuguese Coast

The area around the CIIMAR building, at the Porto de Leixões Cruise Terminal on the northern Portuguese coast, is a hub for cyanobacterial diversity due to its continuous maritime traffic. This makes the site ideal for uncovering new taxa and documenting already known species. Terrestrial cyanobacteria are underexplored in the northern Portugal coast: here we describe four new species and report on cyanobacterial diversity around the CIIMAR building. The study is based on a polyphasic analysis of 13 isolates, belonging to seven genera in the orders Leptolyngbyales (1 strain), Desertifilales (1), Oculatellales (1), Oscillatoriales (2), Chroococcidiopsidales (3), Geitlerinematales (1) and Nostocales (4). Among these, four were classified as new species in the genera <i>Aliterella, Gloeocapsopsis, Compactococcus</i> and <i>Desertifilum</i>. Additionally, the species <i>Desertifilum salkalinema, D. fontinale</i> and <i>D. dzianense</i> were synonymized with the type <i>D. tharense</i>. The isolate LEGE 221420 has a parietal and/or fascicular arrangement of thylakoids, unprecedented in cyanobacteria, confirming that this character is unstable and cannot serve as a taxonomic marker at the genus level. • Four new cyanobacterial species are described. • <i>Gloeocapsopsis expansa</i> sp. nov. LEGE 221420 exhibits both parietal and fascicular arrangement of thylakoids. • <i>Desertifilum salkalinema, D. fontinale</i> and <i>D. dzianense</i> were synonymized with the type <i>D. tharense</i>.