Cryptonemia undulata Sond.

Scientific Description

Habit and structure. Thallus medium red to red-brown fading to greenish-yellow, membranous and cartilaginous, 5–22 cm high, with strongly undulate upper branches, irregularly laterally branched, 5–10 mm broad, 80–180 µm thick, with rounded apices and more-or-less smooth margins, with branched stalks 1–10 cm long and 1–2 mm broad formed by loss of the lamina from the midrib which extends into the lower part of the fronds; proliferations from midrib common. Holdfast discoid to conical, 2–6 mm across; epilithic. Structure of a relatively narrow cortex 4–6 cells thick, outer cells 3–4 µm across and slightly elongate in section, inner cells ovoid and up to 10–14 µm across, stellate cells absent or rare; midrib formed by development of vertical rows of cells from the outer cortical cells. Medulla broad, of densely entwined filaments 4–6 µm in diameter, with prominent refractive ganglioid cells with relatively straight arms. Rhodoplasts discoid, several per cell.

Reproduction. Sexual thalli probably dioecious, female ampullae in upper branches, arising in outer medulla. Carpogonial branch ampullae small, with 1–5 secondary filaments. Auxiliary cell ampullae larger, with several long secondary filaments reaching almost to the thallus surface. Carposporophytes 80–160 µm across, with a persistent basal auxiliary cell, slight involucre and small ostioles. Spermatangia not observed. Tetrasporangia sparsely scattered in the outer cortex in an irregular tissue 3–4 cells thick developed from the original outer cortical cells, 20–30 µm long and 8–12(–15) µm in diameter, irregularly cruciately divided.

Distribution. India (?). Geraldton, W. Aust., to Westernport Bay, Vic.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 182–184 (1994)]