Electronic Flora of South Australia Family Fact Sheet

Tribe LAURENCIEAE Schmitz 1889: 447

Phylum Rhodophyta – Family Rhodomelaceae

Thallus pulvinate or erect and branched, radially or bilaterally, branches terminated by an apical depression surrounding an axial filament, with apical trichoblasts and 2 or 4 pericentral cells per axial cell; axial and pericentral cells obscure within the cortex shortly below the branch apex. Thallus epilithic, epiphytic or parasitic.

Reproduction: Gametophytes dioecious. Procarps borne on lower cells of trichoblasts, with a 4-celled carpogonium and 2 multicellular sterile groups. Carposporophyte with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia. Cystocarps ovoid, pedicellate, sessile or partly immersed, pericarp ostiolate, corticate and 3–6 cells thick. Spermatangia borne on apical trichoblasts or on filaments arising from epidermal cells within apical or adjacent depressions.

Tetrasporangia situated in the outer cortex, formed on the outer end of elongate pericentral cells or cut off from outer or epidermal cells, with 2 cover cells; tetrasporangia subspherical to ovoid, tetrahedrally or decussately divided.

Type genus: Laurencia Lamouroux 1813: 130.

Taxonomic notes: The Laurencieae has included 4 genera (Kylin 1956, p. 552), Laurencia Lamouroux, Rodriguezella Schmitz and the parasitic Riccardia Derbês & Solier and Janczewskia Solms-Laubach, of which the first and last occur on southern Australian coasts.

The first genus, Laurencia, within which several subgenera and sections have previously been recognised (Saito 1967; Saito & Womersley 1974; has recently been separated into 3 genera (Garbary & Harper 1998; Nam 1999), viz.

Laurencia Lamouroux (1813), with 4 pericentral cells, epidermal cells connected laterally by secondary pit-connections and containing corps en cerise, spermatangia borne on trichoblasts in apical receptacles, and tetrasporangia cut off from pericentral cells usually in parallel arrangement, with horizontal cover cells.

Chondrophycus (Tokida & Saito in Saito 1967, p. 72) Garbary & Harper (1998, p. 194) with 2 pericentral cells, epidermal cells in most species without secondary pit-connections and corps en cerise, spermatangia borne on trichoblasts in apical receptacles, and tetrasporangia cut off from pericentral cells usually in right-angle arrangement, with horizontal cover cells. Nam (1999) considers that the only definite feature separating Chondrophycus and Laurencia is the number of pericentral cells.

Osmundea Stackhouse (1809), resurrected by Nam et al. (1994), with 2 pericentral cells, spermatangia borne on filaments arising from epidermal cells in pits near apices, and tetrasporangia produced laterally from epidermal cells with longitudinal cover cells.

Species of Osmundea apparently do not occur on southern Australian coasts.

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.

KYLIN, H. (1956). Die Gattungen der Rhodophyceen. (Gleerups: Lund.)

LAMOUROUX, J.V.F. (1813). Essai sur les genres de la famille des thalassiophytes non articulées. Ann. Mus. Hist. Nat., Paris 20, 21–47, 115–139, 267–293, Plates 7–13.

NAM, K.W. (1999). Morphology of Chondrophycus undulata and C. parvipapillata and its implications for the taxonomy of the Laurencia (Ceramiales, Rhodophyta) complex. Eur. J. Phycol. 34, 455–468.

NAM, K.W., MAGGS, C.A. & GARBARY, D.J. (1994). Resurrection of the genus Osmundea with an emendation of the generic delineation of Laurencia (Ceramiales, Rhodophyta). Phycologia 33, 384–395.

SAITO, Y. & WOMERSLEY, H.B.S. (1974). The southern Australian species of Laurencia (Ceramiales: Rhodophyta). Aust. J. Bot. 22, 815–874.

SAITO, Y. (1967). Studies on Japanese species of Laurencia, with special reference to their comparative morphology. Mem. Fac. Fish. Hokkaido Univ. 15(1), 1–81, Plates 1–18.

SCHMITZ, F. (1889). Systematische Übersicht der bisher bekannten Gattungen der Florideen. Flora, Jena 72, 435–456, Plate 21.

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 LAURENCIEAE

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