Portrait of Haematococcus pluvialis (Flotow, 1844), a widely distributed volvocid flagellate. Thin cytoplasmic strands traverse the clear mucilaginous layer to connect the protoplast to the spherical cell wall. Single large cup-shaped chloroplast. Two equal-length flagella are also seen traversing the mucilaginous layer. Reddish carotenoid pigments are concentrated in the cell center here. The inconspicuous stigma is seen at 1 o'clock near the proroplast surface. Several pyrenoids are visible here. There are multiple small contractile vacuoles. refractile cytoplasmic crystals are present in this individual. From ephemeral freshwater pool near Boise, Idaho, March, 2005. DIC.