Four new species of Padina (Dictyotales, Phaeophyceae) from the western Pacific Ocean, and reinstatement of Padina japonica

Molecular phylogenetic analyses of Padina species collected from the western Pacific Ocean using rbcL and mitochondrial cox3 genes revealed the occurrence of four distinctive clades of unknown Padina species clade A (= Padina okinawaensis sp nov) from Ryukyu Islands (Japan), Hawaii, Indonesia and Thailand, clade B (= Padina undulata sp nov), clade C (= Padina terricolor sp nov) and clade D (= Padina fasciata sp nov) from Ryukyu Islands (Japan) Morphologically, these new taxa are all bistratose species, and different from any known species in the following morphological features P okinawaensis sp nov, reniform or circular thallus of centre margin with inconspicuous hair lines on the superior surface of the thallus, and reproductive organs (oogonia and tetrasporangia) in small groups or discontinuous sori under thin flakes of calcium on the inferior surface, P undulata sp nov, circular or semicircular thallus with undulate margin, conspicuous hair lines on both surfaces of the thallus, oogonial and tetrasporangial sori in continuous or discontinuous lines covered with a persistent indusium, and cylindrical oogonia. P terricolor sp nov, grayish brown on the inferior surface of the thallus, and oogonial and tetrasporangial sori in continuous lines covered with a persistent indusium. P fasciata sp nov, broad white stripes on both surfaces of the thallus due to unique calcification, and oogonial and tetrasporangial sori in continuous lines, which are entirely embedded in a gelatinous layer, on the inferior surface of the thallus In addition, the independence of Padina japonica from Padina sanctae-cructs is suggested on the basis of molecular and morphological evidence