Pterocladia rectangularis (A.H.S.Lucas) Womersley & Guiry
The marine benthic flora of southern Australia 141 (1994)
Conservation Code:
Not threatened
Naturalised Status: Native to Western Australia
Name Status:
Current
Scientific Description
John Huisman & Cheryl Parker,
Monday 20 June 2011
Habit and structure. Thallus medium to dark red, cartilaginous, forming erect tufts (5–)10–25(–30) cm high, with one to several pinnate to bipinnate (rarely tripinnate) axes, with pinnae and pinnules arising in close, regular series almost at right angles to the parent branch, becoming denuded below. Axes strongly compressed, linear, 1.5–2.5 mm broad throughout their length, thickened near the thallus base and above 600–800 µm thick, with occasional adventitious pinnae from the face of the lower axes. Pinnae 5–15 mm long, 0.5–1(–1.5) mm broad (B/T 4–8), slightly constricted basally with some becoming indefinite laterals to 10 cm long. Pinnules similar to young pinnae, (3–)5–8 mm long and 400–800 µm broad, basally constricted and usually tapering above, in regular close series separated usually by 0.7–1.5 times their basal width. Holdfast discoid-conical, 1–5 mm across, becoming fibrous; epilithic. Structure. Cortex 2–3 cells thick, outer cortical cells with the protoplast 3–5 µm across in surface view, walls moderately thick; medulla of elongate cells with many hyphae in older parts; rhizines profuse, mainly in outer medulla in young and mid thallus, throughout medulla in older axes.
Reproduction. Fertile ramuli borne on margins of pinnules. Cystocarps single, subterminal on ramuli, swollen, 250–350 µm across, unilocular with a single prominent ostiole, 60–100 µm in diameter, in the raised pericarp; carposporophyte broad-based with carposporangia in short chains maturing apically, clavate to ovoid, 18–25 µm in diameter. Spermatangial sori covering ends or upper halves of terete to slightly compressed ramuli 1–1.5 mm long and 150–250 µm in diameter, spermatangia cut off directly from outer cortical cells, 4–6 µm long and about 1 µm in diameter, forming terminal subspherical spermatia about 1 µm in diameter. Tetrasporangial stichidia short-stalked, terete to slightly compressed, becoming swollen terminally or centrally, 0.5–1.5 mm long and 100–150(–200) µm broad. Tetrasporangia arising acropetally, derived from cortical cells and lying in the outer medulla and inner cortex, ovoid, 60–100 µm in diameter, decussately cruciately divided.
Distribution. Safety Bay, W. Aust., to the Isles of St Francis, S. Aust., usually in deep water or shaded pools.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 141–142 (1994)]
