Laurencia shepherdii Y.Saito & Womersley

Scientific Description

Habit and structure. Thallus red to red-purple, soft, radially branched, usually basally denuded, branches terete, laterals irregular to subopposite; axes 1.5–3 mm in diameter, decreasing to ramuli 0.7–1(–1.5) mm in diameter and 1–3 mm long, slightly basally constricted and with truncate apices. Holdfast discoid, 3–5 mm across; epilithic or occasionally epiphytic on seagrasses or coralline algae. Structure. Epidermal cells rounded and 25–50 µm across near apices, elongating to L/D 2 on lower axes, with secondary pit-connections and corps en cerise, with frequent intercellular spaces between cortical cells; lenticular thickenings absent. Cells with discoid rhodoplasts, chained in larger cells.

Reproduction. Gametophytes dioecious. Procarps not observed. Carposporophytes with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia 35–70 µm in diameter. Cystocarps sessile, broad-based, conical to ovoid 0.8–1(–1.2) mm in diameter; pericarp ostiolate, 5–6 cells thick. Spermatangial receptacles on dense, short ramuli 1–1.2 mm in diameter, with broad apices. Tetrasporangia in simple to clustered ramuli 0.7–1 mm in diameter and 1–2 mm long, often subdistichous or subtristichous when young, in parallel arrangement, cut off abaxially, 80–130 µm in diameter.

Distribution.Shark Bay, W. Aust., to San Remo, Vic.

Habitat. L. shepherdii is a shallow sublittoral species on rough-water to sheltered coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 464–466 (2003)]