- Reference
- Mar.Benth.Fl.S.Australia 240 (2003)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus dark red-brown, 1–4 cm high, tufted, with prostrate axes bearing slender, moderately to densely branched, erect branches bearing rhodoplastic trichoblasts from each segment on a one quarter spiral; pericentral cells 4, all branches ecorticate. Attachment by rhizoids from prostrate branches; epiphytic on seagrasses or algae. Structure monopodial, with dome-shaped apical cells and trichoblasts cut off from subapical cells 4–6, with pericentral cells just below this; mature branches 90–140(–170) µm in diameter, segments L/D 1–1.5. Trichoblasts 0.5–1.5 mm long, branched more or less in an upwardly curved plane, basally branched 1–3 times, 1–2 cells apart, tapering gradually with long, slender, unbranched ends (sometimes lost); basal cells 35–55 µmin diameter and L/D (1–)1.5–2, mid cells 15–20 µmin diameter and L/D 2–4, and the slender ends 10–12 µmin diameter, cells L/D (1–)1.5–3. Rhizoids arising from pericentral cells, 1–5 cells long, with multicellular haptera. Lateral branches arising irregularly radially, on basal cell of trichoblasts. Cells uninucleate; rhodoplasts discoid, sometimes chained.
Reproduction. Gametophytes dioecious. Procarps arising on suprabasal cell of trichoblasts, the segment becoming polysiphonous. Carposporophytes with a slight basal fusion cell and branched gonimoblast bearing clavate terminal carposporangia 20–30 µmin diameter. Cystocarps almost sessile, ovoid, 300–500 µmin diameter, with a pronounced, usually flared, neck 80–140 µmlong; pericarp ecorticate, with 12–16 erect filaments, each cell cutting off 2 outer isodiametric cells. Spermatangial organs on lower to mid cells of trichoblasts, ovoid, 45–90 µmin diameter and L/D 1–2, with a sterile basal cell only, and 3–6 axial cells bearing lateral initials which divide and produce the outer layer of spermatangia. Tetrasporangia in lesser branch systems 1–2 mm long, with trichoblasts on each segment, spirally arranged and one per segment, slightly bulging the branch; tetrasporangia 50–80 µmin diameter, with cover cells.
Distribution. King George Sound, W. Aust., to Westernport Bay, Vic., and SE Tas.
Habitat. V. adunca occurs in sheltered conditions, most commonly as an epiphyte on seagrasses.
[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 240–242 (2003)]