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Electronic Flora of South Australia Family Fact Sheet
Phylum Rhodophyta – Family Rhodomelaceae
Thallus erect, rarely prostrate, radially or occasionally bilaterally branched, branches with clear axial and pericentral cells surrounded by a broad, compact, cellular cortex (except in Coeloclonium). Apex rounded or depressed, with a short, monopodial, apical filament cutting off pericentral cells and trichoblasts. Pericentral cells 5, becoming elongate parallel to the axial cells (except in Coofoclonium and tetrasporangial branches of Chondria). Pericentral and inner cortical cells in many species with distinctive thickenings on the cell walls. Lateral branches arising on the basal cell of trichoblasts.
Tetrasporangia formed in lesser branches, sometimes in axillary clusters, cut off from pericentral or occasionally inner cortical cells, subspherical, tetrahedrally divided.
Type genus: Chondria C. Agardh 1817: xviii, nom. cons.
Taxonomic notes: The Chondrieae contains 7 or 8 genera, of which one (Cladurus) probably belongs in a separate tribe since it does not have discoid spermatangial plates which are a distinctive feature of the tribe. Other features are the clear presence of pericentral cells throughout the thallus and tetrasporangia cut off mostly from the pericentral cells.
* (key) Cladurus differs from all other Chondrieae in having terete spermatangial organs, not discoid, plate-like ones. It is almost certainly not a member of the Chondrieae, but whether it should be placed in any other tribe (e.g. Polysiphonieae) or as a separate tribe is uncertain.
References:
AGARDH, C.A. (1817). Synopsis Algarum Scandinaviae. (Berling: Lund.)
SCHMITZ, F. & FALKENBERG, P. (1897). Rhodomelaceae. In Engler, A. & Prantl, K., Die natürlichen Pflanzenfamilien. T.1. Abt. 2, pp. 421–480. (Englemann: Leipzig.)
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 GENERA OF CHONDRIEAE
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1. Branches bearing short, stout spines | ACANTHOPHORA |
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1. Branches without such spines | 2 |
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2. Branches partly hollow or vesicular throughout most of thallus, basally constricted (sometimes also along branches); pericentral cells elongate at right angles to axial cells throughout the thallus | COELOCLONIUM |
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2. Branches parenchymatous and compactly cellular in mature parts, pericentral cells parallel to and of similar length to axial cells (except close to apices and where tetrasporic in Chondria) | 3 |
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3. Pericentral cells large, sharply separated from the small-celled cortex, branches showing transverse partitions corresponding to tiers of pericentral cells; spermatangial organs terete, borne as a branch on trichoblasts | CLADURUS * |
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3. Pericentral cells surrounded by cells grading to the outer cortex, without surface partitions; spermatangial plates discoid, with sterile-cell margins | 4 |
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4. Cortex in transverse section with rings of larger cortical cells separated by bands of rhizoids; cystocarps stalked; stichidia clustered in axils of lateral branches | HUSSEYA |
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4. Cortex in transverse section without rings of larger cortical cells separated by rhizoids; cystocarps sessile or short-stalked; tetrasporangia in lesser branches | CHONDRIA |
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