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Electronic Flora of South Australia Genus Fact Sheet

Genus ROBEA Womersley, gen. nov.

Phylum Rhodophyta – Family Delesseriaceae

Thallus erect, complanately and marginally branched, branches more or less linear, margins linear to convolute, apices usually rounded, with occasional surface bladelets, blades with a distinct midrib arising below the apices and forming a short basal stipe; microscopical veins absent; holdfast of clumped rhizoids; epiphytic. Structure. Apices of blades with or without small apical cells, level with the margin or slightly protruding and with only occasional cells dividing by anticlinal walls, with frequent irregular intercalary divisions but usually without recognisable axial or lateral cell rows. Blades monostromatic when young, becoming tristromatic and polystromatic near the base and in the midrib, with cortical cells equivalent and primary layer cells of similar size to cortical cells; cells multinucleate.

Reproduction: Gametophytes dioecious. Procarps scattered, with the primary cell cutting off two elongate cells parallel to blade length, one forming a group of cover cells and the other producing a 4-celled carpogonial branch and a group of 2 sterile cells, with the carpogonial branch lying between the groups of cover cells and sterile cells. Carposporophyte with a small basal fusion cell and a moderately branched gonimoblast with large terminal carposporangia. Cystocarps hemispherical, ostiolate, pericarp 4–7 cells thick usually with no collar. Spermatangial sori scattered, ovate, with the primary cells producing a layer of initials with outer elongate spermatangia.

Tetrasporangial sori ovate, scattered on blade wings, with tetrasporangia in 2 layers, cut off from inner cells of cortical chains 4–6 cells long.

Type species: R. costata Womersley, sp. nov.

Taxonomic notes: Robea is characterised by the branch apices which usually do not have distinct protruding apical cells, but occasionally these are present. However, only few marginal cells dividing by anticlinal walls occur, and cells below the apical cells or the marginal apices divide in an irregular manner, and cell rows (whether axial or lateral) are not recognisable. These features probably place Robea (and Nitospinosa) as a separate group, related to the Phycodrys and Valeriemaya [Millar & Wynne (1992a)] groups which do show distinct axial and second-order cell rows. Valeriemaya also has a single apical cell to each blade and the blades are monostromatic except at the midrib. In reproductive features, Robea is similar to Nitophyllum and its allies, especially in the procarps, but also differs in having a strongly developed midrib; it is also similar to Valeriemaya reproductively, though carposporangia for this genus are not described.

Robea is named for the township of Robe, which is central to its distribution.


MILLAR, A.J.K. & WYNNE, M.J. (1992a). Valeriemaya gen. nov. (Rhodophyta), with a discussion of Apical Organizations within the Delesseriaceae. Br. Phycol. J. 27, 131–143.

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

Author: H. B. S. Womersley

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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