Ramicrusta melanoidea K.R.Dixon

Scientific Description

Habit and structure. Thallus dark maroon to brownish red, with faint concentric bands, lightly calcified within and flexible, composed of spreading closely appressed tightly adherent blades 90–225 μm and 8–15 cells thick. Hypothallus composed of longitudinally staggered parallel filaments, the cells 12–38 μm long and 5–13 μm wide, tapering at their ends, c. 25 μm tall and rhomboidal in vertical section, often developing a thick ventral cuticle. Perithallus consisting of dorsally assurgent filaments arising at broad angles (70–85°); perithallial coxal cells and suprabasal cells ±isodiametric, often with secondary pit connections to cells of adjacent filaments. Upper perithallial cells lacking secondary pit connections, becoming shorter distally or occasionally narrow and elongate. Hairs deeply pigmented basally, hyaline distally, 12–20 μm long, 10–18 μm diam. Rhizoids infrequent, unicellular, short and peg-like, c. 18 μm long and 7 μm thick

Reproduction. Reproductive structures not seen.

Distribution. Known only from Adele Island, north-western Australia, and Vanuatu.

[After K.R. Dixon in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 239 (2018)]