Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Halymeniaceae
H. harveyana J. Agardh 1892: 55. De Toni 1905: 1539.
H. floresia sensu Harvey 1862: pl. 214 (in part).
Thallus (Fig. 55A) light to medium red or red-brown, 10–45 cm high, soft and mucilaginous (adhering strongly to paper), complanately and profusely branched with 4–5 orders of tapering laterals, occasionally with small surface leaflets; axes 1–3 cm broad, main laterals (0.5–) 1–2 cm broad and 300–400 µm thick, lesser laterals 3–10 mm broad, ultimate ones 1–2 mm broad and tapering to an acute apex. Holdfast discoid, 1–3 mm across, stipe 1–5 cm long, cuneate; epilithic. Structure (Fig. 55B) of a relatively thin cortex 5–6 cells broad, with an outer layer of 2–3 anticlinal cells 3–4 µm in diameter and L/D 1.5–3 (–4), cut off from ovoid cells, with the inner cortical cells 20–40 µm across and becoming stellate; medulla lax with widely spaced filaments, most crossing transversely; refractive ganglionic cells (Fig. 55C) present, only slightly thickened. Rhodoplasts elongate, becoming ribbon shaped and branched.
Reproduction: Sexual reproduction unknown.
Bisporangia (Fig. 56B) scattered, on mid cortical cells, ovoid, 14–20 µm long and 12–16 µm in diameter, with a single transverse division.
Lectotype from Port Phillip Heads, Vic. (Harvey, Alg. Aust. Exsicc. 435E); in Herb. Agardh, LD, 22337.
Selected specimens: St Francis I., Isles of St Francis, S. Aust., 10–13 m deep (Shepherd, 6.i.1971; AD, A37984). Elliston, S. Aust., drift (Womersley, 27.ii.1959; AD, A22210). Port Moorowie, Yorke Pen., S. Aust., 3 m deep (Kald, 27.i.1969; AD, A33899). Pennington Bay, Kangaroo I., S. Aust., drift (Kraft & Min Thein, 3.xii.1971; AD, A41389). Encounter Bay, S. Aust., drift (Womersley, 1.ii.1976; AD, A46963). Nora Creina, S. Aust., 4–5 m deep (Kraft 4715, 18.ii.1974; AD, A46015). Queenscliff, Vic., 14 m deep (AIMS-NCI, Q66C 3338-T, 9.ii.1990; AD, A60292). Walkerville, Vic., drift (Sinkora A2296, 7.iii.1976; AD, A48421).
Distribution: Isles of St Francis, S. Aust., to Walkerville, Vic.
Taxonomic notes: Halymenia floresia is apparently widespread in the tropical Indo-Pacific; sexual plants are known from as far south as Perth, W. Aust. (MELU, A39446), and a plant with tetrasporangia from Esperance on the south coast (AD, A18945). J. Agardh separated H. harveyana from H. floresia by its more profuse branching and its thicker and more densely cellular thallus. These characters, however, are variable, and the southern Australian plants cannot be separated vegetatively from the type variety. Sexual plants have not been collected on southern Australian coasts and bisporangia appear to be the only means of reproduction. This life history variation warrants retention of harveyana as a subspecies of H. floresia, but further studies are clearly needed.
H. harveyana is superficially similar to Gelinaria ulvoidea, but is thinner, more branched, and has a much laxer medulla than the latter.
AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.
DE TONI, G.B. (1905). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 4, pp. 1523–1973. (Padua.)
HARVEY, W.H. (1862). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
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.
Illustrations in Womersley Part IIIA, 1994: FIGS 55 A–C, 56B.
Figure 55 enlarge
Fig. 55. A–C. Halymenia floresia subsp. harveyana (A, AD, A46963; B, C, AD, A60292). A. Habit. B. Transverse section of young thallus. C. Refractive ganglionic cells in surface view (squash). D, E. Halymenia kraftii (AD, A60297). D. Habit. E. Carposporophyte within slight involucre.
Figure 56 enlarge
Fig. 56. A. Halymenia floresia subsp. floresia (AD, A18945). Transverse section of thallus with tetrasporangia. B. Halymenia floresia subsp. harveyana (AD, A60292). Transverse section of thallus with bisporangia. C–F. Halymenia kraftii (C, AD, A41636; D, AD, A60297; E, AD, A60468; F, AD, A61374). C. Carpogonial branch ampulla. D. Auxiliary cell ampulla, spread laterally. E. Transverse section of cortex with spermatangia. F. Transverse section of cortex with tetrasporangia.
State Herbarium of South Australia