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Polysiphonia decipiens Mont.

This name is not current. Find out more information on related names.

Reference
Prodr.Gen.Phyc. 5 (1842)
Conservation Code
Not threatened
Naturalised Status
Native to Western Australia
Name Status
Not Current

Scientific Description

Habit and structure. Thallus dark brown-red, drying very dark brown to almost black, 1–15(–25) cm high, irregularly and densely branched (especially in rough-water forms) on all sides with one to a few or several clumped axes, bearing frequent, often short, patent, laterals, often fastigiate above when fertile; hooked branch ends occasionally present. Attachment by rhizoids from prostrate parts; epilithic or epiphytic on larger brown algae, seagrasses (Posidonia, Amphibolis and Heterozostera) and occasionally on red algae. Structure. Basal axis erect or with a very short prostrate part, with rhizoids cut off from the lower pericentral cells. Lower main axes 300–1000(–1500) µm in diameter with segments L/D 0.2–0.3, decreasing to 250–750(–1000) µm in diameter with segments 0.2–1(–2) in mid parts and to (100–)200–300 µm in diameter with segments L/D 0.2–0.5 in branchlets; lateral branchlets often markedly narrower and with shorter segments than the parent branch, especially in robust forms; branchlets tapering fairly abruptly to pointed apices, often with profuse trichoblasts but commonly denuded in rough-water or older plants; lateral branches arising from basal cell of trichoblasts, with cicatrigenous branches below. Pericentral cells 7, rarely 8, ecorticate, subisodiametric and forming irregular segments in branchlets and often throughout most of the thallus in rough-water forms, becoming elongate (L/D 1.5–3) and forming regular segments in main branches of deeper- or calmer-water forms; trichoblasts formed on every segment with a divergence of about one quarter, up to 2 mm long, 2–4(–6) times furcate, varying from moderately slender (basal cell 25–40 µm in diameter) to robust (basal cell 40–60 µm in diameter); scar cells prominent. Rhodoplasts discoid, scattered or in chains.

Reproduction. Gametophytes dioecious. Carposporophytes with a small basal fusion cell and short, gonimoblast with clavate terminal carposporangia 35–55 µm in diameter. Cystocarps subsessile, globular to slightly ovoid (basally broadest), not or only slightly urceolate with small ostiolar cells, 350–700 µm in diameter; pericarp ostiolate, 2 cells thick, outer cells angular, isodiametric. Spermatangial branches developing as one branch of a trichoblast, elongate ovoid to cylindrical, often basally broadest, 150–300 µm long and 50–100 µm in diameter, without sterile apical cells when mature. Tetrasporangia forming closely spiral series in upper, often elongate, branchlets, often extending below 2–3 branchings, formed from pericentral cells in successive segments and occupying 0.3–0.7 of the branchlet diameter when mature, 60–80 µm in diameter.

Distribution.Shark Bay and Geraldton, W. Aust., around southern Australia and Tas to Wilson Promontory., Vic., and to Newcastle, N.S.W. South I.,Stewart I. and Auckland I, New Zealand, and Tierra del Fuego.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 207–209 (2003)]