Taxonomic updates in the family Leptolyngbyaceae (Leptolyngbyales, Cyanobacteria): the description of Pseudoleptolyngbya gen. nov, Leptolyngbyopsis gen. nov., and the replacement of Arthronema

In this paper, we used the polyphasic approach combining 16S rRNA gene phylogenies, identity (p-distance), 16S-23S ITS secondary structures, and morphological and habitat analyses to describe two new genera of Leptolyngbyaceae, Pseudoleptolynbgya G.S. Hentschke gen. nov. (based on LEGE 16533 and LEGE 16651) and Leptolyngbyopsis G.S. Hentschke gen. nov. (based on LEGE 16524). These strains were sampled from freshwater environments at Figueira da Foz, Monchique and Coimbra, Portugal. Both genera are morphologically and ecologically identical to Leptolyngbya and can only be distinguished from it by molecular analyses. Based on morphological and ITS secondary structure analyses we describe two species of Pseudoleptolyngbya, P. figueirensis and P. monchiquensis. P. figueirensis differs from P. monchiquensis by the denser arrangement of the trichomes, the presence of firm sheaths, the common formation of shorter trichomes (up to 30 cells), and the olive or yellowish-green cell content, which is darker in P. monchiquensis. Moreover, the macroscopic appearance of P. figueirensis is a dense brownish mat, while P. monchiquensis is less dense and reddish. 16S rRNA gene sequences of Arthronema africanum CCALA020 are > 99% identical to Leptolyngbya boryana PCC6306, so we transfer A. africanum to Leptolyngbya, as L. africanoidea.