Herposiphonia versicolor (Hook.f. & Harv.) Falkenb.

Scientific Description

Habit and structure. Thallus dark red-brown to orange-red, largely erect, tufted and densely branched, 2–12 cm high, basally attached with free, terete, more or less pinnate branches with 3 (rarely 4) simple determinate laterals between each indeterminate branch, more or less spirally arranged. Attachment by rhizoids; epiphytic on various hosts, probably also epilithic. Structure. Apices surrounded by dense curved branches; apical cells hemispherical, 10–18 µm in diameter. Pericentral cells 8–10, axes 200–600 µm in diameter, segments L/D 0.4–0.8(–1), determinate laterals mostly 1–3 mm long, 100–200 µm in diameter, segments L/D 1–1.5(–2). Trichoblasts profuse on determinate laterals, 1–2 mm long, much branched, lower cells 25–35 µm in diameter, L/D 1–2(–5), elongate when mature. Rhizoids cut off from pericentral cells, unicellular with digitate haptera. Cells multinucleate; rhodoplasts discoid to elongate, becoming chained.

Reproduction. Gametophytes dioecious. Procarps not observed. Carposporophytes with an inconspicuous fusion cell and short, densely branched, gonimoblast with clavate terminal carposporangia 20–35 µm in diameter. Cystocarps sessile or short-stalked, lateral on determinate laterals, ovoid to slightly urceolate, 300–600 µm in diameter; pericarp ostiolate, 2 cells thick, ecorticate, outer cells rounded. Spermatangial organs replacing trichoblasts, with 1–2 sterile basal cells and a sterile terminal filament 2-several cells long, 35–65 µm in diameter and 150–220 µm long. Tetrasporangia in straight rows in determinate laterals, single per segment, 60–90(–120) µm in diameter, with 3 cover cells.

Distribution.Yanchep, W. Aust., to San Remo, Vic., and around Tas.

[After Womersley, Mar. Benthic Fl. Southern Australia IIID: 292–295 (2003)]