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Electronic Flora of South Australia Genus Fact Sheet

Genus HEMINEURA Harvey 1849a: 116, pl. 45

Phylum Rhodophyta – Family Delesseriaceae

Thallus erect, largely complanately branched with elongate flat axes bearing numerous short, flat, marginal proliferations, the main blades and marginal proliferations with a midrib but not connecting between them. Holdfast discoid to fibrous. Structure. Apical cells segmenting to form axes with each cell cutting off 2 lateral and then 2 transverse pericentral cells, the lateral cells forming second-order rows with occasional cells cutting off third-order cells or short rows; transverse intercalary divisions occur in cells of second- and third-order rows, and only the second-order rows and outermost third-order rows reach the blade margins, with the surface cell arrangement within the blade becoming irregular. Lateral blades arise marginally and exogenously from end cells of slight dentations, which divide as in main axes and develop a midrib which is then separated from the midrib of the parent blade by the wings of the latter. Cortication of the midrib occurs and a cortical layer (becoming 2 cells thick) of small cells covers each side of the blade wings, the transverse section showing dimidiate, regularly arranged, cells.

Reproduction: Gametophytes dioecious. Procarps in series below apices, on transverse pericentral (supporting) cells on both sides of young blades, with each supporting cell cutting off 2 sterile cells and two 4-celled carpogonial branches. Carposporophyte with a basal branched fusion cell, much branched gonimoblast and short terminal rows of carposporangia maturing sequentially. Cystocarps single on the midrib, hemispherical, ostiolate, with a pericarp several cells thick. Spermatangial sori scattered on the blades, small to extensive, with spermatangia cut off from cortical initials.

Tetrasporangial sori scattered to extensive and linear between midrib and margins, with 2 irregular layers of tetrasporangia of varying ages, cut off from cortical cells and with an overlying cortex of small cells.

Type species: H. frondosa (Hooker & Harvey) Harvey 1849a: 116.

Taxonomic notes: Hemineura was established by Harvey in 1849, having been suggested by Hooker & Harvey in 1847 in describing the species.

Hemineura is a distinctive genus, characterised by its habit with marginal exogenous branching when outer cells of small dentations develop further as apical cells of lobes, cutting off axial and pericentral cells, and thus resulting in a region of wing cells of the parent blade lying between the midrib of the latter and the midrib of the new marginal blade. The presence of 2 carpogonial branches and 2 sterile groups on each supporting cell, as well as the presence of only few third-order cells or rows and the irregular surface cell arrangement of the blades are also distinctive. Some of these features occur also in Dicroglossum crispatulum, which differs in habit, midrib arrangement and origin of laterals.

H. frondosa is probably the only species of Hemineura. H. schmitziana De Toni & Okamura has been placed by Yoshida (1974) in Marionella, and H. hassleri Taylor in a new genus Austrofolium by Wynne (1988), which includes also H.? howellii Taylor. Hemineura has been placed in a separate tribe, the Hemineureae, by Lin et al. (2001).


HARVEY, W.H. (1849a). Nereis Australis, pp. 65–124, Plates 26–50. (Reeve: London.)

LIN, S.-M., FREDERICQ, S. & HOMMERSAND, M.H. (2001). Systematics of the Delesseriaceae (Ceramiales, Rhodophyta) based on large subunit rDNA and rbc L sequences, including the Phycodryoideae, subfam. nov. J. Phycol. 37, 881–899.

WYNNE, M.J. (1988). Austrofolium gen. nov. (Delesseriaceae, Rhodophyta) from the Pacific coast of South America. Syst. Bot. 13, 111–119.

YOSHIDA, T. (1974). On the systematic position of Hemineura schmitziana DeToni & Okamura, a member of the Delesseriaceae, Rhodophyta. Bot. Mag. Tokyo 87, 11–16.

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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