Cofirmation on taxonomic status of Spatoglossum pacificum Yendo(Dictyotaceae, Phaeophyceae) based on morphology and plastid protein coding rbcL rbcS, psaA, and psb A gene sequences

Phenological, morhological and molecular characteristics of Spatolossum pacificum Yendo are examined. S. pacificumhas an annual life cycle composed of sporophytes with an apparent absence of male and female gametophytes in Korea. The seasonal growth of this species explains that the annual growth is closely related to the monthly variation of water temperature. S. pacificum has protruding reproductive structures above the outmost cortical layer. Although thisobservation is restricted to several species, this reproductive organ on the thallus can make S. pacificum distinguishable from S. crassum and S. lactum. The morphogenesis of a midrib at the base of S. pacificum in this study is the same as those of Dictyopteris but different from those of S. crassum and S. lactum, suggesting that S. pacificum is closely related to Dictyopteris. In the comparison of plastid gene sequences among species of Spatoglossum and Dictyopteris, S. pacificum ismore similar to D. divaricata and D. undulata than those of S. crassum in rbcL, rbcS, psbA, and psaA. This resultis congruent with the anatomical characteristic of a midrib at the base of the thallus and the protrusion of reproductive organs on the thallus. The phylogenetic relationship based on these plastid genes also shows that S. pacificum is included in Dictyotpteris clade and separated from S. crassum. We transfer Spatoglossum pacificum Yendo to Dictyopteris Lamouroux based upon differences of anatomical characteristics of the midrib, the existence of reproductive organs on thallus and the molecular analyses. KCI Citation Count: 0