Nanopera merrifieldiae (J.Agardh) S.M.Wilson & Kraft

Scientific Description

Habit and structure. Thallus dark brown-red, 6–20 cm high, axes (1–2 mm broad) branched for 2–3 orders and bearing opposite, determinate, pinnate, tapering laterals 3–6 mm long and 400–800 µm broad, axes and laterals compressed; some laterals becoming indeterminate as a further order of branching. Apices initially curved, later flat. Holdfast discoid; epilithic. Structure. Apices curved, tapering. Axial cells with 5 pericentral cells, 2 dorsal, 2 lateral and 1 ventral, the dorsal and ventral cells dividing to form a 2-layered medulla of uniform cells, with a cortex 2–3 cells thick. Secondary cortex occurs centrally on older axes. Short, branched trichoblasts occur at apices of young pinnate laterals. Cells uni- or multinucleate; rhodoplasts discoid, chained in larger cells.

Reproduction. Reproductive organs occur on short, branched, shoots in the axils of the pinnate laterals. Procarps with 4-celled carpogonial branches, soon on polysiphonous shoots and pericarpic. Carposporophytes with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia 30–50 µm in diameter. Cystocarps globose, stalked, 500–800 µm in diameter; pericarp ostiolate, 5–6 cells thick. Spermatangial organs unknown. Tetrasporangial stichidia clustered on axillary short shoots, 600–1500 µm long, curved, compressed, corticated, 300–550 µm broad, with two rows of opposite tetrasporangia 100–150 µm in diameter.

Distribution.Geraldtonto King George Sound, W. Aust.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 380 (2003)]