Liagora mannarensis V.Krishnam. & Sundararajan

Scientific Description

Habit and structure. Thallus to 8 cm high, pale pink, irregularly dichotomously branched, with numerous short lateral branches, mucilaginous, lightly calcified, attached by a discoid holdfast. Axes to 2.0 mm in diameter near base, tapering to 0.2–0.5 mm in diameter at apex. Medullary filaments 10–25 µm in diameter, with rhizoidal filaments 5–10 µm in diameter. Assimilatory filaments 300–350 µm long, sparsely dichotomously or trichotomously branched, mostly peripherally; lower cells 5–12 µm in diameter; outer cells 7–15 µm in diameter.

Reproduction. Monoecious. Spermatangia solitary or paired on mother cells on outer cortical cells. Carpogonial branches 3- or 4-celled, strongly curved, on midcortical cells in a central position on the supporting cell. Involucral filaments initially directed proximally from the cell above the supporting cell, distally from the cell below it, later enveloping the carpogonial branch. Zygote dividing transversely, with both daughter cells dividing longitudinally to produce the gonimoblast. Involucral filaments usually branched, generally slightly moniliform; cells ovoid or cylindrical, narrower than those of assimilatory filaments. Mature gonimoblasts hemispherical in section, compact, bearing solitary terminal carposporangia, circular in polar view, with a halo of involucral filaments sharply demarcated from the gonimoblast and not mingling with it. Fusion cell composed of carpogonial branch cells.

Distribution. Known from the Wallabi and Easter Groups of the Houtman Abrolhos, W. Aust.

Habitat. Epilithic in sandy areas with slight to moderate water movement, at depths of 12–30 m.