Pterocladiella capillacea (J.F.Gmel.) Santel. & Hommers.

Scientific Description

Habit and structure. Thallus dark red, 4–15(–20) cm long, cartilaginous, forming densely branched tufts or masses, with few to numerous erect, bi- to tripinnate fronds from an entangled stoloniferous base 2–20 mm across. Axes linear and relatively straight, flat, 600–1000(–1500) µm broad throughout, apices tapering to spathulate, complanately and distichously branched every 1–2 mm, usually denuded below. Pinnae (1–)2–5 cm long and 0.6–1 mm broad, compressed. Pinnules subopposite to alternate, 0.5–3(–5) mm long and 200–400 µm broad, basally constricted. Holdfasts of clumped rhizoids; epilithic. Structure. Cortex 3–5 cells thick, outer cells in surface view more-or-less in rows, ovoid, with the protoplast 2–4 µm across; medulla of elongate cells; rhizines profuse throughout the medulla.

Reproduction. Cystocarps single or possibly compound, more-or-less centrally positioned in each pinnule, round to elongate-ovate, 200–500 µm across, unilocular, with 1(–3) ostioles in the raised pericarp; carposporophyte elongate and tufted from a restricted transverse base around the axial cell but several axial cells in length, carposporangia developing in short chains and maturing apically, ovoid, 15–25 µm in diameter. Spermatangial sori (not seen) on pinnules, ovate to elongate. Tetrasporangial sori ovate to elongate, 1–2(–3) mm long, in compressed pinnules with only slight medulla; tetrasporangia of mixed age, derived from cortical cells and lying in the inner cortex, ovoid, irregularly decussately cruciately divided, 25–40 µm in diameter.

Distribution. Widespread in temperate seas, extending into the subtropics. In Australia, from Cottesloe, W. Aust. (probably from further north) around southern Australia and Tas., to Stradbroke I., Qld.

Habitat. P. capillacea occurs on coasts of rough to moderate water movement.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 139–141 (1994) added as Pterocladia capillacea]