Catenella nipae Zanardini

Scientific Description

Habit and structure. Thallus dark brown-red to purple, fading to yellow-brown, in dense tufts or masses (1–)2–10 cm high and across, much branched from the upper end of elongate-ovoid segments (1–)3–6(–10) mm long and 1–2 mm broad, upper segments terete, becoming compressed below. Haptera numerous, developing at the distal ends of segments which then produce 1–3 new segments just subterminally. Usually on mangroves or jetty piles, sometimes epilithic. Structure with one or a small group of apical cells, producing several slender medullary filaments, each cell with a single lateral, which form a laxly branched, reticulate, medulla and a cortex 3–4 cells thick, outer cells 4–8 µm in diameter and L/D 1–2. Rhodoplasts laminate, few per cell.

Reproduction.Sexual reproduction non-procarpic. Carpogonial branches (2–)3-celled, borne on mid medullary cells near apices of young segments, relatively straight and directed outwards, with a prominent trichogyne and sometimes with a sterile cell on the basal cell. Connecting filament single. Auxiliary cell a cell of one of the central filaments, producing a single gonimoblast initial towards the segment apex, later forming a branched fusion cell (with a stalk) which cuts off radially chains of ovoid carposporangia 20–30 µm in diameter. Cystocarps swollen, 0.5–1 mm in diameter; stipitate; pericarp absent, cortex not or slightly thickened, with a slight ostiole. Spermatangia unknown. Tetrasporangia scattered (often dense) in the cortex of young segments, laterally to basally pit-connected, ovoid, 50–75 µm long and 30–45 µm in diameter.

Distribution.Indo-pacific tropics; north island of New Zealand. Westernport Bay, Vic., and Botany Bay, N.S.W., northwards, in calm situations often on mangroves or jetty piles.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 449–450 (1994)]