Schizymenia dubyi (Duby) J.Agardh

Scientific Description

Habit and structure. Thallus medium to dark red-brown, mucilaginous, foliose, simple to variously and irregularly lobed, often lacerate from above (sometimes to the base), margin smooth to somewhat ruffled, 10–60 cm high and 5–15 cm broad with branches (1–)2–10 cm broad, 300–600(–1000) µmthick, base cuneate, usually expanding fairly abruptly from a narrow stipe. Holdfast discoid, 1–3 mm across, with one to a few fronds; epilithic. Structure of a cortex 60–100 µmthick, of discrete branch systems (6–)8–10 cells long, inner cells subspherical to ovoid, 6–10(–14) µmin diameter, with tapering to elongate outermost cells 2–4 µmin diameter, L/D (1–)1.5–2. Gland cells usually but not always present in outer cortex, ellipsoid-ovoid to clavate, 14–30 µmlong and 6–10 µmin diameter, with granular contents. Medulla of moderately dense entangled filaments 3–5(–10) µmin diameter. Rhodoplasts several per cell, discoid to elongate.

Reproduction. Sexual thalli monoecious. Carpogonial branches 3-celled with a relatively straight trichogyne, borne on an inner cortical cell, with the supporting cell cutting off a 1–2-celled sterile row; adjacent cells staining darkly and also cutting off sterile cells. Carposporophyte produced from an inner cortical (auxiliary?) cell, 100–240 µmacross and more or less ovoid with relatively few ovoid carposporangia 15–20 µmin diameter, protruding into the medulla and with a distinct depressed ostiole through the cortex. Spermatangia developed on outer cortex, elongate and tapering outwardly, 2–3 µmin diameter and L/D 3–4, cutting off ovoid spermatia. Tetrasporophytes crustose, with erect filaments producing zonately divided tetrasporangia (unknown in southern Australia).

Distribution.Europe, Mediterranean, Japan. In southern Australia, Fremantle, W. Aust., and Pondalowie Bay, S. Aust., to Point Lonsdale, Vic.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 280–281 (1994)]