Hydrolithon reinboldii (Weber Bosse & Foslie) Foslie

Scientific Description

Habit and structure. Thallus green, brownish pink or purple, often epilithic and forming rhodoliths, encrusting, up to 1200 μm thick, or lumpy with branches 1–6 mm wide, dimerous in construction. Medulla multilayered, either dimerous or composed of branched filaments (via regrowth); cells 13–45 μm long, 5–12 μm diam. Cortex multilayered; cells 7–12 μm long, 4.5–10.0 μm diam. Cortical filaments each ending in an intercalary initial cell that subtends 1 (or 2) epithallial cells, these either rounded or flattened, 5–8 μm long, 6–14 μm diam. Intercalary initials generally shorter than the cortical cells that they produce. Trichocytes scattered throughout the upper cortex, not evident deeper in cortex, formed from modified cortical cells 12–17 μm long, 9–15 μm diam.

Reproduction. Tetrasporangial conceptacles level with the surface or slightly raised, 500–800 μm outside diam., with the conceptacle pore 2 or 3 cell layers below the conceptacle roof; pore lined with large pore cells, these triangular in LS, 35–45 μm long, 17–25 μm diam. Tetrasporangia 120–220 μm long, 72–150 μm diam. Other reproductive structures not observed.

Distribution. Occurs in tropical waters worldwide and in Australia from the Houtman Abrolhos, Western Australia.

Habitat. Epilithic in the intertidal and subtidal to 20 m depth.

[After R.A. Townsend & J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 95–97 (2018)]