Molecular data and culture observations show that the microfilamentous marine alga Uronema marinum Womersley is a member of the genus Okellya Leliaert & Rueness (Cladophorales, Chlorophyta)

The marine microfilamentous green algal genus Okellya Leliaert & Rueness forms a distinct lineage of Cladophorales Haeckel, and currently contains only a single species, Okellya curvata (Printz) Leliaert & Rueness, originally described as Uronema curvatum Printz from Norway. Based on phylogenetic analyses of SSU and LSU rDNA sequences, we show that the Australian Uronema marinum Womersley also belongs to Okellya, and the species is transferred there as O. marina (Womersley) Wetherbee, comb. nov. We provide detailed observations of cultured material and show that O. marina (Womersley) Wetherbee, comb. nov. differs from O. curvata in the presence of pyrenoids, necessitating a revised circumscription of the genus Okellya and family Okellyaceae Leliaert & Rueness.