Laurencia similis K.W.Nam & Y.Saito

Scientific Description

Habit and structure. Thallus sprawling or erect, to 12 cm tall, with 4 or 5 branching orders and with several percurrent or irregularly branched axes arising from a sprawling discoid holdfast. Axes cartilaginous, terete, covered with many short determinate branchlets 0.25–0.75 mm long. Main axes usually 0.50–1.25 mm wide, showing little variation from base to apex, although larger branches can reach up to 3 mm in upper portions of branch. Plants often with a dense covering of substrate debris lodged between branchlets (e.g. shell and coral fragments, and other calcified organisms). Epidermal layer with few secondary pit connections between cells when viewed in longitudinal section. Epidermal cells not palisade in transverse section, 20–30 µm diam., elongate when viewed in longitudinal section, 20–34 µm long. Lenticular thickenings absent in medullary cells; cell walls often thickened. Tetrasporangial plants more densely covered with compound ultimate branchlets than sterile plants.

Reproduction. Tetrasporangia formed in perpendicular arrangement, although the pattern is often difficult to observe due to the short length of fertile branchlets.

Distribution. Occurs from Exmouth to Adele Island, north-western Australia; also known from the type locality, Low Isles, near Port Douglas, north-eastern Queensland.

[After Y. Metti, J.M. Huisman & A.J.K. Millar in Algae of Australia: Marine Benthic Algae of North-western Australia, 2. Red Algae: 528 (2018)]