Electronic Flora of South Australia Family Fact Sheet

FAMILY PLOCAMIACEAE Kützing 1843: 442, nom. cons.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales

Thallus erect, complanately branched, with alternating marginal series of 2–6 compressed lateral branches or ramuli, axes sympodially developed, base stoloniferous (or parasitic and pulvinate). Structure uniaxial, with a central filament surrounded by a pseudoparenchymatous cortex.

Reproduction: Sexual thalli dioecious; procarpic. Carpogonial branches 3-celled, borne on mid cortical cells, with the supporting cell acting as the auxiliary cell. Carposporophyte outwardly directed, with a basal fusion cell producing several gonimolobes with all except the basal cells forming carposporangia, enclosed in a dense cellular pericarp; cystocarps sessile or pedicellate on the upper ramuli of the series, non-ostiolate. Spermatangia developed from surface cortical cells on upper ramuli or on branched tufts in their axils.

Tetrasporangia borne in simple or branched stichidia on the margins of upper ramuli or in branched axillary tufts.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Taxonomic notes: A family of two genera, Plocamium Lamouroux, which is common in cool to warm temperate seas and to which the above description applies, and the pulvinate parasite Plocamiocolax Setchell (1923, p. 395). Details of the type species of Plocamiocolax, P. pulvinata Setchell, are lacking apart from an ultrastructural study of the carposporophyte by Krugens & Delivopoulos (1986). A second species, Plocamiocolax papenfussiana Martin & Pocock (1953, p. 50, figs 2a, 3c, d, 4a) is known from South Africa. Minute parasitic cushions do occur on some specimens of Plocamium on southern Australian coasts but have not been investigated.

References:

KÜTZING, F.T. (1843). Phycologia generalis. (Leipzig.)

KRUGENS, P. & DELIVOPOULOS, S.G. (1986). Ultrastructure of the carposporophyte and carposporogenesis in the parasitic red alga Plocamiocolax pulvinata Setch. (Gigartinales, Plocamiaceae). J. Phycol. 22, 8–21.

MARTIN, M.T. & POCOCK, M.A. (1953). South African parasitic Florideae and their hosts. 2. Some South African parasitic Florideae. J. Linn. Soc., Bot. 55, 48–64, Plates 10–12.

SETCHELL, W.A. (1923). Parasitic Florideae II. Univ. Calif Pubis Bot. 10, 393–401.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.


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