Laurencia nanhaiense sp.nov.,a new species of the genus Laurencia(Rhodomelaceae,Rhodophyta) from China

Laurencia nanhaiense sp.nov. (Rhodomelaceae, Rhodophyta) is described from Hainan and Guangdong Provinces, China.The new species clearly displays one of the defining features of the genus, viz.four periaxial cells per vegetative axial segment.It differs from other closely related species in having a combination of features such as terete axes from a basal system composed of a primary discoid holdfast and a secondary attachment to give rise to many short rhizoids, branching oppositely and alternately, irregularly tristichous or subverticillately polystichous, having more curve branches with very sparse, adventitious ultimate branchlets, non-projecting superficial cortical cells at the apices of ultimate branchlets, presence of longitudinally oriented secondary pit-connections between contiguous superficial cortical cells, absence of lenticular thickenings in the walls of medullary cells, parallel arrangement of tetrasporangia along the axis of stichidia, and presence of intercellular spaces between medullary cells.