Electronic Flora of South Australia Genus Fact Sheet

Genus MALACONEMA Womersley & Shepley 1959: 210.

Phylum Rhodophyta – Family Sarcomeniaceae

Thallus erect, slender, much branched irregularly, branches terete to slightly compressed, with flanking cells only near where carpogonial branches develop or in stichidia; holdfast rhizoidal, discoid. Structure. Apical cell hemispherical, axial cells cutting off 4 pericentral cells in alternating sequence, slightly corticated below; branching endogenous; cells uni- to multinucleate.

Reproduction: Carpogonial branches borne on transverse pericentral cells, with the adjacent lateral pericentral cells cutting off flanking cells. Carposporophytes with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia. Cystocarps sessile, ovoid; pericarp ostiolate, 2 cells thick, outer cells transversely elongate.

Tetrasporangial stichidia formed from ends of lateral branches, fertile segments forming flanking cells; tetrasporangia cut off from lateral pericentral cells, protected by cover cells on each side and the curved flanking cell.

Type species: M roeana (Harvey) Womersley & Shepley 1959: 210.

Taxonomic notes: Malaconema contains 2 species, the type and M minimum Hollenberg (1963, p. 169) from the central Pacific, placed in the Sarcomeniaceae largely due to the structure of the stichidia with flanking cells, carpogonial branches with associated flanking cells and cystocarps, separated from other genera by the absence of flanking cells, in vegetative branches. The genus was included within the Rhodomelaceae by Silva et al. (1996, p. 526), separate from other genera of the Sarcomeniaceae (which they placed in the Delesseriaceae), but its apical development, cystocarp structure and reproduction clearly ally it with other genera of the Sarcomeniaceae (see also Abbott 1999, p. 342).

References:

ABBOTT, I.A. (1999). Marine Red Algae of the Hawaiian Islands. (Bishop Museum Press: Honolulu, Hawai'i.)

HOLLENBERG, G.J. (1963). A new species of Malaconema (Rhodophyta) from the Marshall Islands. Phycologia 2, 169–172.

SILVA, P.C., BASSON, P.W. & MOE, R.L. (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. (Univ. California Press: Berkeley.)

WOMERSLEY, H.B.S. & SHEPLEY, E.A. (1959). Studies on the Sarcomenia group of the Rhodophyta. Aust. J. Bot. 7, 168–223.

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.

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