A major goal of phylogeographic analysis using molecular markers is to understand the ecological and historical variables that influence genetic diversity within a species. Here, we used sequences of the mitochondrial Cox1 gene and nuclear internal transcribed spacer to reconstruct its phylogeography and demographic history of the intertidal red seaweed Chondrus ocellatus over most of its geographical range in the Northwest Pacific. We found three deeply separated lineages A, B and C, which diverged from one another in the early Pliocene-late Miocene (c. 4.5-7.7 Ma). The remarkably deep divergences, both within and between lineages, appear to have resulted from ancient isolations, accelerated by random drift and limited genetic exchange between regions. The disjunct distributions of lineages A and C along the coasts of Japan may reflect divergence during isolation in scattered refugia. The distribution of lineage B, from the South China Sea to the Korean Peninsula, appears to reflect postglacial recolonizations of coastal habitats. These three lineages do not coincide with the three documented morphological formae in C. ocellatus, suggesting that additional cryptic species may exist in this taxon. Our study illustrates the interaction of environmental variability and demographic processes in producing lineage diversification in an intertidal seaweed and highlights the importance of phylogeographic approaches for discovering cryptic marine biodiversity.
Three species of marine algae, two browns and one red were newly reported from the eastern and the southern coast of Korea including Cheju Island. Their vegetative and reproductive structures were described. Colpomenia phaeodactyla Wynne et J.N. Norris (Scytosiphonaceae, Phaeophyceae) commonly occurred in middle to lower intertidal zone of southern coast. Plants consisted of clusters of elongated and hollow sacs arising from an adherent colpomenioid base. Plurilocular sporangia were multiseriate, forming dense, extensive sori over the erect sacs. Cutleria adspersa (Mertens ex Roth) De Notaris (Cutleriaceae, Phaeophyceae) was collected from subtidal region of Cheju Island. It was characterized by broadly fan-shaped habits with golden brown colour and hair-fringed margins, attached by rhizoids along undersurface. Halarachnion latissimum Okamura (Furcellariaceae, Rhodophyceae) was found adrift from several areas of southern coast. Plants were brownish red, filmy and delicate, membranaceous roundish fronds. Cystocarps were globular and formed under the cortical layer. Tetrasporangia were oblong and zonately divided.
Two species of Apoglossum is newly recorded in Korea collected from subtidal habitats of Jeju Island. Apoglossum minimum Yamada has previously been known only from the coast of Japan. It is characterized by having corticated midrib but lacking microscopic veins. Apoglossum gregarium (Dawson) Wynne is reported for the first time from the north western coast of Pacific Ocean. It has been distinguished by its ecorticate midrib from the former species. Their morphological characteristics in detail and taxonomic issues are discussed.
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