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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Spongoclonieae
Thallus erect, 5–15 cm high, much branched with one to several main axes and lateral branches, bearing basally branched lateral branchlets with long, unbranched terminal parts; axes corticated below by entwined rhizoids from the basal cells of branchlets or laterals. Active apices spirally branched, usually surrounded by lower mature branchlets. Cells multi nucleate.
Reproduction: Gametophytes dioecious. Carpogonial branches borne on the subterminal cell of short, 3-celled, branches, with a carpogonial branch of 4 small cells, and the third cell bearing two sterile periaxial cells; post-fertilization the 3 sterile cells enlarge and become rounded, and the auxiliary cell produces 1–4 successive rounded gonimolobes, with the carposporophyte becoming surrounded by involucral branchlets from below. Spermatangial heads are borne on lower cells of lateral branchlets, elongate-ovoid.
Polysporangia sessile on lower cells of lateral branchlets, subspherical, with about 32 spores.
Type species: L. comatum J. Agardh 1892: 43 [= L. hirtum (Hooker & Harvey) Womersley].
Taxonomic notes: Lophothamnion is closely related to Spongoclonium, having very similar procarps and carposporophytes, including enlarged and rounded sterile cells as in Spongoclonium, but differs in having polysporangia (32–40 spores) instead of tetrasporangia. This conspicuous difference in sporangia (Spongoclonium having typically 4 spores per sporangium, very rarely with 8) is considered a satisfactory difference to separate the 2 genera.
References:
AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.
The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.
Publication:
Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia
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