Sporolithon episoredion (W.H.Adey, R.A.Towns. & Boykins) Verheij

Scientific Description

Habit and structure. Thallus encrusting to lumpy, 50–950 μm thick; lumps up to 14 mm long and wide. Medulla a thin layer, with filaments in a plumose pattern; cells 7–25 μm long, 5–10 μm diam. Cortex multilayered, with secondary pit connections and lateral fusions between cells of adjacent filaments. Cortical cells 12–26 μm long, 12–26 μm diam. Cortical cell filaments ending in an initial 7–10 μm long, 5–7 μm diam. Initials subtending a single layer of flattened epithallial cells 2–5 μm long, 7–12 μm diam.

Reproduction. Sporangial sori forming large patches, 500–3500 μm wide, raised (150–225 μm) above the thallus surface; loculi 260–290 μm high and 145–165 μm wide. Sori becoming buried in the thallus. Sporangial locules surrounded by calcified filaments of 2 or 3 long cells (22–50 μm long, 10–15 μm diam.) and 2 or 3 shorter cells. Each sporangium situated below a pore 38–45 μm diam., in the form of cruciate tetrasporangia, the spores 125–155 μm long, 135–145 μm diam., subtended by a prominent stalk cell.

Distribution. Northern western Australia, also in Indonesia and Hawaii.

Habitat. Eplithic in the subtidal.

[After R.A. Townsend & J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 144–146 (2018)]