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Electronic Flora of South Australia Genus Fact Sheet

Genus PTILOTA C. Agardh 1817: xix, 39, nom. cons.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Ptiloteae

Thallus erect, complanately branched, with main axes bearing indeterminate laterals for 3 or 4 orders, with opposite branches but one of each pair strongly developed and the opposite one short; determinate branches with opposite, shorter, branchlets; branches becoming corticated by closely appressed filaments from close to apices and oval in section; holdfast discoid, rhizoidal. Structure. Apical cells of indeterminate branches dividing obliquely, with first alternate laterals and later a smaller opposite branch. Periaxial cells producing ascending and descending branched cortical filaments forming a cortex of small cells, with rhizoids developing around the axial cells. Cells uninucleate.

Reproduction: Gametophytes dioecious. Procarps subterminal on indeterminate branches, with the axial cell bearing 4 periaxial cells, one (the supporting cell) with a sterile group and a lateral 4-celled carpogonial branch; the apical cell, sterile group and the 3 vegetative periaxial cells all produce short filaments with terminal hair cells. Auxiliary cells developing post-fertilization a gonimoblast of 2–3 successive globose lobes, with a basal fusion cell. Involucral branchlets develop from periaxial cells of the next lower segment. Spermatangia borne in clusters around cells of uniseriate filaments.

Tetrasporangia occur terminally in clusters on ultimate uniseriate filaments, pyriform, tetrahedrally divided.

Type species: P. gunneri Silva, Maggs & Irvine in Maggs & Hommersand 1993: 38.

Taxonomic notes: The above generic description of Ptilota is based on that of Maggs & Hommersand, and is provided to permit differences in P. hannafordii to be assessed.


AGARDH, C.A. (1817). Synopsis Algarum Scandinaviae. (Berling: Lund.)

MAGGS, C.A. & HOMMERSAND, M.H. (1993). Seaweeds of the British Isles. Vol. 1. Rhodophyta. Part 3A, Ceramiales. (HMSO: London.)

The Marine Benthic Flora of Southern Australia Part IIIC complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
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