Cosmopolitan geographic distribution of Phaeosaccion multiseriatum (Phaeosacciaceae, Phaeosacciophyceae), and description of P. westermeieri sp. nov. from Chile

The minute marine multicellular heterokont alga originally described as “Giraudyopsis stellifer” by P.J.L. Dangeard, nom. inval., from Atlantic France, was re-isolated by the germling emergence technique and classified according to psaA and psbC sequences. It is genetically similar (99–100 % identity) to Phaeosaccion multiseriatum R.A. Andersen, L. Graf et H.S. Yoon recently described from the NE Pacific, an ephemeral alga of wide geographical distribution. We isolated it also from substratum samples collected in Korea and the Falkland Islands, where it had not been reported previously. Two isolates of similar morphology from the coast of Chile had the same nuclear ribosomal SSU sequence but differed from P. multiseriatum and P. okellyi R.A. Andersen, L. Graf et H.S. Yoon from New Zealand in psaA and psbC sequences (3–4 % genetic distance). These two isolates are here described as Phaeosaccion westermeieri sp. nov.. Our isolations of P. multiseriatum and P. westermeieri are a further demonstration that the germling emergence technique can reveal microscopic multicellular benthic algae that are easily overlooked in the field.