Ganonema farinosum (J.V.Lamour.) K.C.Fan & Yung C.Wang
Acta Phytotaxonomica Sinica 492 (1974)
Conservation Code:
Not threatened
Naturalised Status: Native to Western Australia
Name Status:
Current
Scientific Description
John Huisman & Cheryl Parker,
Monday 20 June 2011
Habit and structure. Thallus (gametophyte) brownish red, moderately calcified, 5–15 cm high, terete, subdichotomously branched every 0.5–2 cm with occasional lateral branches; lower thallus 1–1.5(–2) mm in diameter, tapering slightly to apices. Holdfast discoid, 1–3(–5) mm across; epilithic or epiphytic on larger brown algae. Structure of a medulla of large, elongate cells 50–150 µm in diameter, mixed with slender rhizoids in older parts, and a cortex 350–450 µm broad, of branch tufts of filaments consisting of a basal cell, cut off from a medullary cell, which produces several straight to slightly curved cortical filaments, branched near the base 1–4 times, 15–20 µm in diameter, cells L/D 2–3, not or only very slightly constricted at their cross walls, rhodoplasts irregularly stellate, each with a central pyrenoid. Basal cells of cortical branch tufts producing slender rhizoids which grow over and between the medullary cells. Tetrasporophyte minute, filamentous, branched.
Reproduction. Sexual thalli dioecious. Carpogonial branches borne on the basal to third cell of the cortical branch tufts, almost straight, of 4 cells with a conical carpogonium. Zygote dividing transversely, the upper cell segmenting obliquely to produce a dense compact carposporophyte 120–200 µm across in surface view, of relatively few cells, the end cells developing into ovoid-clavate carposporangia proliferating from cells below sheaths of previous ones. No fusion cell developed. Sterile post-fertilization filaments develop from cortical cells adjacent to the carpogonium, and form a slight and loose involucre around the carposporophyte, consisting of filaments similar to the cortical filaments. Spermatangia produced at apex of cortical filaments, from a globose-ovoid head 40–70 µm across, consisting of a central row of 4–6 cells cutting off 2–3 orders of cells, the ultimate elongate spermatangial initials cutting off ovoid spermatangia 2–4 µm in diameter. Tetrasporophyte with irregularly divided tetrasporangia and monosporangia.
Distribution. Tropical and subtropical seas, extending into warm temperate regions. Isolated shallow (and warmer) bays around southern Australia from Cowaramup Bay (and further north), W. Aust., to Port Noarlunga, S. Aust.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 94–96 (1994) as Liagora farinosa]
