Chondria angustissima Gordon-Mills & Womersley

Scientific Description

Habit and structure. Thallus brown-red, fading to yellow-red, 2–10 cm high, very slender, much branched radially for 3–4 orders, branches spreading and often entangled, terete; lower branches or axes 500–750 µm in diameter, grading to lesser branchlets 150–200(–250) µm in diameter. Holdfast discoid, 200–500 µm across; epiphytic on Zostera or Gracilaria, or unattached, or epilithic, in sheltered estuarine conditions. Structure. Apices pointed, occasionally slightly rounded, with an apical filament 10–12 cells long, cortex becoming a few cells broad; epidermal cells 15–25 µm in diameter and L/D 5–12; rhizoids and cell wall thickenings absent. Trichoblasts profuse at and near branch apices, 1–2 mm long. Lateral branches arising from basal cells of trichoblasts. Cells multinucleate; rhodoplasts discoid to elongate.

Reproduction. Gametophytes dioecious. Procarps on a lower cell of trichoblasts. Carposporophytes with a branched, basal fusion cell and short branched gonimoblast with clavate terminal carposporangia 30–55 µm in diameter. Cystocarps ovoid, shortstalked, 400–600 µm in diameter, with a short basal spur; pericarp ostiolate, with 10–14 erect filaments, 2 cells thick, ecorticate. Spermatangial plates formed as a basal branch on trichoblasts, irregularly discoid to obcordate, 200–350 µm across, with sterile terminal cells to the trichoblast branches, but otherwise spermatangia formed by marginal cells. Tetrasporangia in swollen lesser branches 200–250 µm in diameter, on 2–3 pericentral cells per axial cell, 100–120 µm in diameter, with conspicuous cover cells.

Distribution.Leschenault Inlet, W. Aust., to Port Stevens, N.S.W.

Habitat. C. angustissima is confined to sheltered estuarine conditions.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 426–427 (2003)]