Peyssonnelia capensis Mont.
Annales des Sciences Naturelles 177-178 (1847)
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 pale to medium red or grey-red, (1–)2–5(–12) cm across, cartilaginous, orbicular or becoming divided into 2–5 broad lobes, 230–450 µm thick, usually radially striate and with more or less concentric growth zones and granular inclusions apparent in surface view (magnified), epilithic and closely attached apart from free margins (or upper parts of larger plants) which often roll upwards on drying. Structure. Basal layer of radiating lines of cells, each cell 4–8(–10) µm in diameter and L/D 2–4, producing from their lower side multicellular rhizoids with their first cell (the hypobasal cell) inclined forwards and usually bent where it emerges from the thallus sheath (calceolate), sometimes cut off as a short, broad, hypobasal cell lying within the thallus sheath; hypobasal calcification present. Erect filaments assurgent at 20–30(–40)°, attached to the anterior upper side of the basal layer cells, 8–10(–12) µm in diameter with cells L/D 2–4 below, branching from some to most of the first 4 cells, erect above and 6–8 µm in diameter with uppermost cells more or less isodiametric; cystoliths in small to relatively large clusters of few to several adjacent cells in the mid to upper thallus region; surface calcification occasionally present.
Reproduction. Sexual plants with low, somewhat diffuse nemathecia, with slender paraphyses 200–250 µm and 8–10 cells long; carpogonial branches 3–4 cells long, lateral from basal cell of paraphyses; gonimoblasts forming branched systems of elongate-ovoid cells 6–8 µm in diameter. Tetrasporangial nemathecia superficial, low, medium yellow to dark red, 1–2 mm across and ovate to elongate, more or less in concentric lines; paraphyses 90–140 µm and 5–6 cells long; tetrasporangia 50–60 µm long and 9–15 µm in diameter, decussately cruciately divided.
Distribution. S. Africa; Madagascar; New Zealand; Brazil. In southern Australia, from Rottnest I., W. Aust., to northern N.S.W. and around Tas.
Habitat. P. capensis is a common species, from low tide level (in shaded situations) to 38 m deep.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 155–157 (1994)]
