FIGURES 3–8. Vegetative anatomy of the holotype of Sporolithon indopacificum (L 3964509). 3. Holotype specimen showing lumpy growth form with swollen, crowded protuberances (scale bar = 10 mm). 4. Magnified view of the protuberances showing their contiguously fused nature and numerous superficial sori (white arrowheads) scattered across the protuberances. Note that sori are often abraded or shed from the surface (black arrowheads) (scale bar = 2 mm). 5. Vertical section showing layers of S. indopacificum crusts (L) overgrowing itself in a superimposed manner (scale bar = 200 μm). 6. Vertical section through the monomerous thallus showing the epithallus (arrowhead) and a predominantly thick cortex (C) subtended by a thin medulla (M) (scale bar = 100 μm). 7. Vertical section of the ventral region of the thallus showing a plumose medulla (M) and cortical filaments (C) joined primarily by secondary pit connections (arrowheads) (scale bar = 50 μm). 8. Vertical section of the dorsal region of the thallus showing a single layer of flared epithallial cells (arrow) subtended by a layer of subepithallial initials (i). Note the layer of senescent epithallial cells (e) being shed, the primary pit connections between adjacent cortical filaments (black arrowheads) and a single, rare cell fusion (white arrowhead) (scale bar = 20 μm).