Dasya naccarioides Harv.

Scientific Description

Habit and structure. Thallus light to medium to dark red with the axes paler than the branch tips, mucilaginous, with one to a few pyramidal and much branched robust axes 10–30(–50) cm high, terminal pseudolateral tufts prominent. Main axes simple or branched, heavily corticated, (1–)2–3 mm in diameter, percurrent, branched at intervals of 0.4–1 cm, denuded below. Laterals 2–20 cm long, decreasing in length above, 1–2 mm in diameter, themselves similarly branched but slenderer, arising from the basal cell of the fourth order of branching of a young pseudolateral. Holdfast discoid, 5–20 mm across; usually epilithic. Structure. Apices sympodial, pericentral cells 5, becoming obscured in older laterals and axes by profuse rhizoidal development and enlargement of their cells. Pseudolaterals one per segment, spirally arranged, 2–3 mm long, with (3–)5–7 subdichotomies every 1(–2) cells from the base, giving usually 40–50 ultimate simple branches 7–12 cells long, tapering from the basal cells (50–)80–130 µm in diameter and L/D 0.7–1.5 to the ultimate cells 10–25 µm in diameter and L/D 15–30. Adventitious monosiphonous filaments absent. Rhodoplasts discoid to elongate.

Reproduction. Gametophytes dioecious. Procarps 1–3 borne alternately on the lower segments of the pseudolaterals (which then become polysiphonous). Carposporophyte with a basal fusion cell and carposporangia in rows of 2–4, obovoid-clavate to subspherical. Cystocarps sessile on lateral corticated axes, urceolate to ovoid, (700–)950–1300 µm in diameter, 1150–1550 µm long, with a short neck; pericarp 4–5 cells thick, outer cortical cells irregular in age and position. Spermatangial branches on the lower branches of the pseudolaterals, cylindrical, 150–300 µm long and 50–65 µm in diameter with 10–20 fertile segments, on a 1–2 celled monosiphonous stalk and with 1–2 globular cells (rarely a short filament) at the apex. Stichidia on lower branches of the pseudolaterals, cylindrical, on a 1–2-celled monosiphonous stalk, 150–600 µm long and 90–125 µm in diameter with 6–12 fertile segments each with 5 pericentral cells, all of which become fertile. Tetrasporangia 25–45 µm in diameter, each with 2(–3) cover cells, subspherical to slightly higher than broad, covering about half the sporangium.

Distribution. Albany, W. Aust., to Kiama, N.S.W., and around Tas.

Habitat. Common, just subtidal, species on Victorian and Tasmanian coasts.

[After Parsons & Womersley in Womersley, Mar. Benthic Fl. Southern Australia IIIC: 465–466 (1998)]