Floiophycus walteradeyi R.A.Towns. & Huisman

Scientific Description

Habit and structure. Thallus 100–1000 μm thick, encrusting to warty, with branches to 1 mm long, monomerous in construction. Thallus surface not smooth, appearing patterned, with irregular mounds. Medulla multilayered, plumose, composed of branched filaments with cells 20–35 μm long, 10–15 μm diam. Cortex multilayered; cortical filaments ending in squat initials that often fuse laterally with adjacent initials, but then elongate and divide to form epithallial cells or fused or unfused cortical cells. Cortical cells 5–25 μm long, 5.0–22.5 μm diam., with multiple fusions with laterally adjacent cells and with cells above and below. Epithallium a single layer of oblong cells with c. a quarter of the volume being cytoplasm; cells 5–15 μm long, 5–15 μm diam., those above megacyte groups often forming white patches that are visible on the thallus surface. Megacytes in pustular groups, often on tops of thallus mounds, throughout the upper cortex and becoming buried in the cortex, formed from modified cortical cells, 37–50 μm long, 20–39 μm diam.

Reproduction. Sporangial conceptacles raised, transversely ovate in section, 250–325 μm outside diam., c. 200 μm internal diam. Roof of mature conceptacles with 4 or 5 cell layers. Tetrasporangia 60–80 μm long, 30–35 μm diam. Other reproductive stages not observed.

Distribution. Known from the southern Kimberley and offshore shoals, Western Australia.

Habitat. epilithic in the subtidal.

[After R.A. Townsend & J.M. Huisman in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 117 (2018)]