Crassilingua marginifera (J.Agardh) Papenf.

Scientific Description

Habit and structure. Thallus medium to dark red-brown, 5–20(–30) cm high, irregularly much branched with linear laterals borne marginally or proliferously from within the margin. Main branches 3–6(–8) mm broad, lesser branches 2–4 mm broad, with short constricted stipes, apices rounded; all branches with a broad, central midrib but no lateral veins. Holdfast divided, fibrous with rhizoids, 2–5(–10) mm across; epilithic or rarely epiphytic. Structure. Apical cell obconical but indistinct, segmenting to an axial filament and 2 lateral pericentral cells which form second-order cell rows reaching the thallus margin, with the cells cutting off irregularly third-order cells or rows both abaxially and adaxially; transverse pericentral cells not recognisable as such. Transverse intercalary divisions occur in axial and other cells, giving a compact but irregular cell arrangement in surface view. Cortication commencing close to apices, with the blades soon becoming polystromatic and 120–160 µm thick, with a central layer of large, isodiametric to ovoid, cells 35–60 µm across and usually 2 layers of smaller, isodiametric and angular cells 10–15 µm across; margins 250–300 µm thick due to slight separation of the 5 layers of cells. Midrib broad, with 4–8 cell layers over 10–20 primary cells in transverse section. Mature cells multinucleate; rhodoplasts discoid.

Reproduction. Gametophytes dioecious. Procarps scattered on blades between midrib and margins, details not observed. Fusion cell with an apical group of sterile conical cells. Carposporophytes with a prominent basal fusion cell and much branched gonimoblast with short terminal chains of ovoid carposporangia 15–20 µm in diameter. Cystocarps scattered between midrib and margins, 1–1.5 mm across, ostiolate, swollen on both sides of the blade; pericarp thick, with anticlinal chains of 8–10 cells. Spermatangial sori elongate-ovate, between midrib and margins, with inner cortical cells dividing anticlinally to form a layer of initials, each cutting off several elongate spermatangia. Tetrasporangial sori elongate, between midrib and margins, 300–350 µmthick, with the outer cortical cells forming anticlinal filaments (paraphyses) 80–100 µm and 4–7 cells long, surrounding the ovoid tetrasporangia, 30–40 µmm in diameter, which are borne terminally on 2–4-celled filaments.

Distribution. W. Aust (?)., and Elliston, S. Aust., to Gabo I., Vic., and SE Tas.

Habitat. C. marginifera occurs mainly in deep water or shallow but shaded positions on rough water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 80–83 (2003)]