Dasya cliftonii Harv.

Scientific Description

Habit and structure. Thallus medium red to red-brown, soft, mucilaginous, (5–)10–30 cm high, with one to a few relatively slender axes bearing alternate laterals radially to subdistichously, denuded below but with tufted filaments on branch ends. Main axes somewhat flexuous, 400–700 µm in diameter, bare, corticated, irregularly subdichotomous, with alternate laterals, more-or-less pyramidal in outline. Laterals with 2–3 orders of branches, more-or-less subdistichous and mostly two segments apart (some on each segment), alternately divaricate, arising from the first branch of a pseudolateral or adventitiously from the basal cell. Holdfast discoid, 1–3 mm across; epiphytic on Amphibolis. Structure. Pericentral cells 5, quickly corticated by rhizoidal filaments, leaving the pericentral cells visible in transverse section but becoming separated from each other by slender rhizoids, some of which later become as large as the pericentral cells; outer cortical cells irregularly placed, ovoid to elongate. Pseudolaterals arising from each 1(–2) segments, lost from older parts, 1–2 mm long, divaricately and repeatedly branched every 1–2 cells, basal cells 45–65 µm in diameter and L/D 2–5, above gradually attenuate to an acute apex which is often lost. Adventitious monosiphonous filaments absent. Rhodoplasts discoid, becoming chained and reticulate.

Reproduction. Procarps not observed. Carposporophyte with a slight fusion cell and numerous darkly staining cells of the lower pericarp and adjacent vegetative cells, gonimoblast much branched with short terminal chains of ovoid carposporangia 15–20 µm in diameter. Cystocarps sessile on the base of short lateral branches, ovoid, with a slight to distinct neck, 300–600 µm in diameter. Pericarp with 10–14 erect filaments cutting off pericentral and cortical cells which become ovoid and irregularly placed. Spermatangial branches unknown. Stichidia borne as the ultimate branches of pseudolaterals on a single-celled monosiphonous stalk, 400–700 µm long and 100–200 µm in diameter, lanceoid, with about 6 fertile segments and 4 sporangia per segment, arranged in longitudinal rows, often ending in a simple or branched filament. Tetrasporangia 30–55 µm in diameter, each with 2–3 ovoid cover cells.

Distribution. Cliff Head, W. Aust., to Sturt Bay, S. Aust.

[After Parsons & Womersley in Womersley, Mar. Benthic Fl. Southern Australia IIIC: 448–450 (1998)]