Chondria incurva Gordon-Mills & Womersley

Scientific Description

Habit and structure. Thallus medium to dark red-brown, fading to yellow-red, 8–25(–30) cm high, irregularly radially or unilaterally branched for 3–4 orders, branches terete, upper parts of branches frequently curved usually adaxially, with frequent axillary branches; lower axes 1–2(–4) mm in diameter, grading to lesser branchlets 1–1.5 mm in diameter. Holdfast discoid, 1–10 mm across, frequently with basal stolons attached by haptera; epilithic or epiphytic on Amphibolis or algae, occasionally epizoic. Structure. Apices in a distinct depression, with 5 pericentral cells and a broad cortex with epidermal cells 20–50 µm in diameter and L/D 1–1.5(–2.5); axial cells often clear in side view of branches, 50–70 µm in diameter and L/D 1–1.5(–2). Mature axes with distinct rings of pericentral and inner cortical cells, separated by rhizoids, and the lower axes developing a secondary cortex. Cell wall thickenings in mid to lower axes, forming patches or bands on the upper ends and sides of pericentral and inner cortical cells. Trichoblasts profuse at apices, 1–1.5 mm long. Cells with discoid to elongate rhodoplasts, chained in larger cells.

Reproduction. Gametophytes dioecious. Procarps not observed. Carposporophytes with a large basal fusion cell and branched gonimoblast with clavate terminal carposporangia 30–40 µm in diameter. Cystocarps ovoid, 1–1.2 mm in diameter; with a short stalk and a blunt, rounded spur; pericarp ostiolate, corticated, 3–4 cells thick. Spermatangial plates discoid to slightly lobed, 700–800 µm across, with a sterile margin 1(–2) cells broad. Tetrasporangia occur in lesser branches, borne singly on 2–3 pericentral cells per axial cell, 80–130 µm in diameter.

Distribution.Port Denison, W. Aust., to San Remo, Vic.

Habitat. C. incurva is a sublittoral species mainly found on rough-water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 432 (2003)]