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Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales

Thallus erect, subdichotomously to irregularly branched, branches terete to flat, usually firm and cartilaginous. Structure multiaxial, medulla narrow to broad, formed of densely entangled filaments or a core of longitudinal, elongate cells, cortex usually broad, pseudoparenchymatous, with larger, ovoid inner cells and small outer cells.

Reproduction: Sexual thalli probably dioecious, procarpic or non-procarpic. Carpogonial branches borne on inner cortical cells, singly or 2–3 per cell, 2–3 cells long with an outwardly directed trichogyne (sometimes basally reflexed from the carpogonium). Auxiliary cell formed by the supporting cell or an adjacent cortical cell, with diploidization via the hypogynous cell or a short connecting filament. Carposporophyte developing a basal placenta of reticulate cells, with erect, branched filaments producing short terminal chains of carposporangia. Cystocarps protuberant, ostiolate, with a thick pericarp. Spermatangia cut off from outer cortical cells in surface sori.

Tetrasporangia developed on or in the outer cortex in nemathecia, zonately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Taxonomic notes: The Sarcodiaceae includes 3 genera, Sarcodia, Trematocarpus (including Dicurella -Searles 1969) and the little known Chondrymenia Zanardini. Species of the first two genera are known from southern Australia.

Herpophyllum australe J. Agardh (1894, p. 63, figs 10–14; 1898, p. 135; 1899, p. 160, pl. 3 figs 10–16), from Port Phillip Heads, Vic., was placed by J. Agardh in the Delesseriaceae, by Kylin (1924, p. 97) in the Rhodymeniaceae, and in 1956 (p. 558) Kylin referred it to the Sarcodiaceae. Its affinities remain uncertain, but (especially from J. Agardh's illustrations of the cystocarps) it is probably not a member of the Sarcodiaceae.


AGARDH, J.G. (1894). Analecta Algologica. Cont. II. Acta Univ. lund. 30, 1–98, Plate 1.

AGARDH, J.G. (1898). Species Genera et Ordines Algarum. Vol. 3, Part 3 - De dispositione Delesseriearum. (Gleerup: Lund.)

AGARDH, J.G. (1899). Analecta Algologica. Cont. V. Acta Univ. lund. 35, 1–160, Plates 1–3.

KYLIN, H. (1924). Studien über die Delesseriaceen. Lunds Univ. Årsskr. N.F. Avd. 2, 20(6), 1–111.

KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.

SEARLES, R.B. (1969). Observations on the morphology of Trematocarpus dichotomus Kützing and the status of the genus Dicurella. Phycologia 8, 21–25.

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.


1. Thallus branches strongly compressed; medulla of entangled filaments; female reproductive system non-procarpic and polycarpogonial


1. Thallus branches terete to slightly compressed; medullary core of longitudinal filaments; female reproductive system procarpic and monocarpogonial


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