Bostrychia moritziana (Kütz.) J.Agardh

Scientific Description

Habit and structure. Thallus forming dense mats or turfs 1–3 cm high, brown-red to purple, with indeterminate main axes 2–4(–6) cm long bearing determinate laterals 2–5(–10) axial cells apart and 2–3 mm long. Attachment by cladohaptera from indeterminate axes; epilithic or epiphytic on mangroves and salt marsh plants. Structure. Apices straight, apical cells dome-shaped and 20–25 µm in diameter (including thick walls), producing determinate laterals with monosiphonous branches mostly 20–50 cells long. Pericentral cells 4–5(–6), each dividing into 2 tiers, ecorticate. Indeterminate axes 60–100 µm in diameter, axial cells 80–160 µm long; determinate laterals basally 35–60 µm in diameter, monosiphonous branches 25–40 µm in diameter, cells L/D (1–)1.5–3. Cells uninucleate; rhodoplasts discoid.

Reproduction. Gametophytes dioecious. Procarps borne on 3–6 consecutive axial cells of polysiphonous parts of determinate laterals, with 1(–2) per axial cell; carpogonial branches (2–)3 cells long, with a prefertilization group of 2–4 sterile cells and a group of 3–4 cells from an adjacent pericentral cell. Carposporophyte with a short branched gonimoblast and clavate terminal carposporangia 20–25 µm in diameter. Cystocarps on determinate laterals, ovoid to subspherical or slightly urceolate, 500–550 µm in diameter; pericarp ostiolate, with 6 longitudinal filaments, 3 cells thick, outer cells irregular. Spermatangial organs involving 4–12 axial cells of determinate laterals, 30–50 µm in diameter and 100–200 µm long, with 5 pericentral cells, a layer of cortical cells, and an outer layer of spermatangia. Stichidia subapical or intercalary on determinate laterals, with polysiphonous stalks, 100–140 µm in diameter and 5–12(–17) axial cells and 800–1200 µm long, with 4 pericentral cells and tetrasporangia per whorl; tetrasporangia 50–60 µm in diameter, with 2 cover cells.

Distribution.Widely distributed in tropical and temperate seas. In Australia from W. Aust., around southern coasts and Tas., to Qld.

Habitat. B. moritziana occurs in calm, sheltered localities, often under fresh-water influence.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 366–367 (2003)]