Gracilariopsis longissima (S.G.Gmelin) Steentoft, L.M.Irvine & Farnham 1995

    Thallus very delicate, grow up to a metre in length. Thallus highly branched, terete, and erect attached by small circular disc; fronds arises from single main axis, uniformly thin and delicate; branching lateral, rarely subdichotomous, opposite or subopposite in arrangement, frequently alternate; branch tips attenuated; branches up to third or even fourth order, ultimate branches 4-12mm length and 0.5mm thickness. Cortex of 2-4 layers of cells, outermost cells radially elongated, 10µm x 7µm some being modified to form enlarged cyst like cells produced on the surface as tubular hairs, inner cortex cells large and more or less oval. Medulla of 3-5 layers of cells, spherical or ovoid central large cells measure 300µm across; cells of medulla progressively smaller from the centre outwards, oval 18 µm x13µm to141 µm x 154 µm. Transition from cortex to medulla is abrupt. Cystocarps sub- spherical, elevated and scattered. Carpospores are sympodially developed from the tips of the gonimoblast filaments as short series.