|
Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Crouanieae
Thallus erect, often from prostrate basal filaments, much branched with lateral branches arising from axial cells below apices and basal cells of whorl-branchlets and often developing more strongly, axial cells each with 3 whorl-branchlets branched 4–8 times and covering the axis or with axial cells exposed between whorls; laterals 10–20 cells long before initiation of whorl-branchlets; attachment by rhizoidal holdfasts; gland cells absent. Cells uninucleate.
Reproduction: Gametophytes dioecious. Procarps borne in place of whorl-branchlets near branch apices, with a supporting cell bearing a 4-celled carpogonial branch. Post-fertilization the auxiliary cell cuts off a terminal and then lateral gonimolobes, the carposporophyte being surrounded by whorl-branches in a rounded to clavate end of a branch. Spermatangia are cut off from outer cells of whorl-branchlets.
Tetrasporangia are borne on basal cells of whorl-branchlets, sessile, subspherical, tetrahedrally divided.
Type species . C. attenuata (C. Agardh) J. Agardh 1842: 83.
Taxonomic notes: A genus of numerous species, world-wide in distribution.
References:
AGARDH, J.G. (1842). Algae Maris Mediterranei et Adriatici, Observationes in Diagnosin Specierum et Dispositionem Generum. (Fortin, Masson: Paris.)
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
KEY TO SPECIES OF CROUANIA
1. Thallus slimy, enveloped in mucilage. Terminal cells of whorl-branchlets small, rounded | C. mucosa |
1. Thallus not slimy, gelatinous sheath contouring axes and whorl-branchlets at least in mature to older parts of thallus. Terminal cells of whorl-branchlets rounded or elongate | 2 |
2. Plants less than 4 cm high. Erect axes arising from a prostrate base. Terminal cells of whorl-branchlets mostly rounded, L/D | 3 |
2. Plants | 4 |
3. Axial cells elongate, not increasing in L/D in central to lower thallus. Whorl-branchlet whorls becoming separated at maturity to form distinct rings; lower whorl-branchlets some times shorter | C. shepleyana |
3. Central to lower cells of older axes often larger with increased L/D. Whorl-branchlets near-horizontal, outer part spreading and touching or almost so in adjacent whorls | C. destriana |
4. Thallus usually | C. robbii |
4. Thallus up to 4 cm high. Whorl-branchlets | C. brunyana |
Email Contact: State Herbarium of South Australia |