Gracilaria preissiana (Sond.) Womersley
Australian Journal of Botany 109 (1976)
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-brown, fading to grey-red, 3–10(–24) cm high, irregularly and profusely but essentially complanately branched, often proliferous from the margins, lower branches flat, 2–4(–5) mm broad and 300–700 µm thick, upper branches compressed, 200–500 µm broad and 200–300 µm thick. Holdfast discoid or divided, 2–5 mm across, with one to several fronds from short stipes; epilithic or on calcareous substrates. Structure apparently multiaxial, pseudoparenchymatous throughout, with a cortex 2–3 cells thick, outer cells 5–8(–14) µm in diameter and L/D 1–1.5, changing fairly abruptly to the medulla 4–8 cells broad, cells subspherical to ovoid, 50–180 µm in diameter, walls 4–8 µm thick; refractive cells (gland like) often present in the cortex. Rhodoplasts discoid, in chains in medullary cells.
Reproduction. Gametangial thalli dioecious or monoecious. Carpogonial branches 2-celled. Carposporophytes with a basal mass of gonimoblast cells and upper gonimoblast filaments producing short chains of ovoid carposporangia maturing terminally, 12–22 µm in diameter, with occasional traversing nutritive filaments; such filaments fuse with several pericarp cells forming elongate, darkly staining, fused filaments with lateral projections derived from lateral pit-connections, found mainly on the sides and base of the carposporophyte. Cystocarps ovoid, 1–2 mm across, slightly basally constricted; pericarp massive, with anticlinal filaments of cells 10–20 µm across with numerous lateral pit-connections and with a prominent ostiole; inner pericarp absent. Spermatangia in deep lobed pits 115–200 µm broad and 100–250 µm deep, with a small opening. Tetrasporangia sparsely scattered in the cortex, basally pit-connected to inner cortical cells, ovoid, 30–45 µm long and 15–22(–30) µm in diameter, cruciately divided.
Distribution. Houtman Abrolhos and Champion Bay, W. Aust., to Wittelbee Point, S. Aust. Also recorded from Cape York, Qld.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIB: 16–17 (1996)]
