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Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Family Rhodomelaceae – Tribe Laurencieae
Thallus erect, radially to distichously branched for 2–5 orders, usually firm and drying cartilaginous, branches with truncated apices with a depressed apical pit; holdfast discoid or stoloniferous; epilithic or epiphytic. Structure. Apical depression with a central, short, apical filament bearing well-developed trichoblasts and each axial cell with 2 pericentral cells, axial and pericentral cells soon obscured in sectional view; cortex extensive with relatively large, ovoid, compact cortical cells and a small-celled epidermis without secondary pit-connections and without corps en cerise; inner cortical cells with or without lenticular thickenings and rhizoids. Lateral branches arising from basal cells of trichoblasts. Cells uni- or multinucleate, rhodoplasts discoid or elongate, often ribbon-like in larger cells.
Reproduction: Gametophytes dioecious. Procarps on a pericentral cell on the suprabasal cell of trichoblasts, consisting of a lateral sterile group, a 4-celled carpogonial branch and a basal sterile group. Carposporophytes with a basal fusion cell and branched gonimoblast bearing clavate terminal carposporangia, replaced from cells below. Cystocarps lateral on branches, sessile, basally constricted or broad-based and only slightly projecting; pericarp arising pre-fertilization, ostiolate, corticated and 3–6 cells thick. Spermatangia borne in lateral whorls on cells of modified trichoblasts in the apical, cup-like, depressions, the filaments terminated by an enlarged globular cell.
Tetrasporangia borne abaxially on the outer ends of laterally elongate pericentral cells, appearing in side view of axes in "right angle" (to the branch axis) arrangement, tetrahedrally or decussately divided.
Type species: C. cartilagineus (Yamada) Garbary & Harper 1998: 194.
Taxonomic notes: A genus of 16–18 species, with 4 on southern Australian coasts. These species were included in subgenus Chondrophycus by Saito & Womersley (1974), and as for species of Laurencia, all 4 species need detailed study of the number of pericentral cells, origin of tetrasporangia, and other features.
References:
GARBARY, D.J. & HARPER, J.T. (1998). A phylogenetic analysis of the Laurencia complex (Rhodomelaceae) of the red algae. Cryptogamie, Algol. 19, 185–200.
SAITO, Y. & WOMERSLEY, H.B.S. (1974). The southern Australian species of Laurencia (Ceramiales: Rhodophyta). Aust. J. Bot. 22, 815–874.
The Marine Benthic Flora of Southern Australia Part IIID complete list of references.
Publication:
Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
KEY TO SPECIES OF CHONDROPHYCUS
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1. Thallus soft to moderately firm, not drying cartilaginous; epidermal cells not palisade-like but obconical in section of branches | C. brandenii |
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1. Thallus firm, drying cartilaginous; epidermal cells elongate and palisade-like in section of branches | 2 |
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2. Usually epiphytic on Amphibolis; thallus with divergent and relatively distant branches mostly | C. cruciatus |
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2. Epilithic; branches small and prolific or swollen and | 3 |
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3. Thallus with profuse, small, ultimate branchlets | C. paniculatus |
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3. Thallus with stout, swollen, branches; ultimate branchlets reduced to swellings on parent branch, with groups of tetrasporangia along the parent branch | C. tumidus |
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Email Contact: State Herbarium of South Australia |
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