Electronic Flora of South Australia Species Fact Sheet

Mychodea marginifera (Areschoug) Kraft 1978: 551, figs 16, 17, 38, 39.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Mychodeaceae

Synonyms

Euthora marginifera Areschoug 1854: 354.

Gymnogongrus foliosus Harvey 1862: pl. 194; 1863, synop.: xlii. Kützing 1869: 23, pl. 62a, b.

Mychodea foliosa (Harvey) J. Agardh 1872: 35; 1876: 573; 1897: 52. Kylin 1932: 65. Lucas & Perrin 1947: 156.

Thallus (Fig. 166A, B) medium to dark red-brown, 5–15 (–40) cm high, with clustered, flat, subdichotomous main branches 2–10 (–20) mm broad, with marginal, ovate to elongate, basally constricted proliferous laterals 2–4 (–10) mm broad, with rounded apices, and later with small surface proliferations. Holdfast crustose, 1–3 (–5) mm across; epiphytic on Amphibolis and larger algae, or epilithic or on jetty piles. Structure uniaxial but with the apical cell and axial filament apparent only in very young (cultured) plants, older apices domed; mature thallus (Fig. 167B) with an inner medulla of slender filaments, outer medulla of large cells, and a small-celled cortex, outer cells ovoid, 2–4 µm in diameter. Rhodoplasts discoid, becoming ribbon shaped in inner cells.

Reproduction: Sexual thalli monoecious; procarpic; polycarpogonial. Carpogonial branches (Fig. 167C, D) 3-celled, 2–4 borne on enlarged inner cortical cells, auxiliary cell producing gonimoblast filaments thallus-inwards and laterally, forming clusters of ovoid carposporangia 12–20 µm in diameter in the filamentous matrix (Fig. 166C). Cystocarps (1–4) embedded within the rounded tips of main branches (Fig. 167A), 0.8–1.5 µm across; enveloping tissue slight, cortex breaking down outside the persistent auxiliary cell for release of carpospores. Spermatangial clusters (Fig. 167E) scattered, sunken in outer cortex of main branches, with several initials each bearing two elongate-ovoid spermatangia 2–3 µm in diameter.

Tetrasporangia (Fig. 167F) scattered, sometimes in patches, on both surfaces of branches, laterally attached in the outer cortex, ovoid, 36–50 µm long and 15–20 µm in diameter, zonately divided.

Type from Port Phillip, Vic. (Mueller); lectotype in Herb. Areschoug, S.

Selected specimens: Port Denison, W. Aust., drift (Kraft, 14.xii.1971; AD, A44721). Head of Great Australian Bight, S. Aust., upper sublittoral on Amphibolis (Womersley, 4.ii.1954; AD, A19157). Pearson I., S. Aust., 5 m deep (Shepherd, 8.i.1969; AD, A33972). Wanna, S. Aust., drift (Womersley, 19.ii.1959; AD, A22367). Victor Harbor, S. Aust., 3–5 m deep on Amphibolis (R. Lewis, 19.iii.1972; AD, A44726). Port Elliot, S. Aust., drift (Womersley, 10.viii.1957; AD, A21154). Vivonne Bay, Kangaroo I., S. Aust., 1–3 m deep on jetty piles (Kraft, 6.iv.1972; AD, A44722). Pennington Bay, Kangaroo I., S. Aust., sublittoral fringe on Acrocarpia (Kraft, 3.xii.1971; AD, A44723). Robe, S. Aust., 3 m deep on jetty piles (Kraft, 10.ii.1973; AD, A44725). Port MacDonnell, S. Aust., drift on Perithalia (Kraft, 25.ix.1992; MELU, K9092). Lawrence Rock, Portland, Vic., in low pools (Beauglehole, 15.i.1960; A24025). Queenscliff, Vic., drift on Amphibolis (Womersley, 8.iv.1959; AD, A22855). Gabo I., Vic., 13 m deep (Shepherd, 14.ii.1973; AD, A43338). Swansea, Tas., drift on Amphibolis (R. & G. Kraft, 15.xii.1992; MELU, K9278).


Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Port Denison, W. Aust., to Gabo I., Vic., and E Tasmania.

Taxonomic notes: M. marginifera is characterised by the flat branches with marginal (and few surface) proliferations, all with rounded apices, by indistinguishable apical cells and axial filaments, and by the submarginal position of cystocarps. It is a fairly common species, epiphytic (often on Amphibolis or Acrocarpia) or on solid substrates, on rough-water coasts, from low tide level to 11 m deep. It is the most variable in habit of all the species, especially in height and width of the branches.

References:

AGARDH, J.G. (1872). Bidrag till Florideernes Systematik. Acta Univ. hind. 8, 1–60.

AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 - Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)

AGARDH, J.G. (1897). Analecta Algologica. Cont. IV. Acta Univ. lund. 33, 1–106, Plates 1, 2.

ARESCHOUG, J.E. (1854). Phyceae novae et minus cognitae in maribus extraeuropaeis collectae. Ups. Soc. Sci. nova Acta, Ser. III, 1, 329–72.

HARVEY, W.H. (1862). Phycologia Australica. Vol. 4, Plates 181–240. (Reeve: London.)

HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)

KÜTZING, F.T. (1869). Tabulae Phycologicae. Vol. 19. (Nordhausen.)

KRAFT, G.T. (1978). Studies of marine algae in the lesser-known families of the Gigartinales (Rhodophyta). III. The Mychodeaceae and Mychodeophyllaceae. Aust. J. Bot. 26, 515–610.

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

LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)

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

Author: G.T. Kraft & 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.


Illustrations in Womersley Part IIIA, 1994: FIGS 166 A–C, 167 A–F.

Figure 166 image

Figure 166   enlarge

Fig. 166. A–C. Mychodea marginifera (A, AD, A21154; B, AD, A44725; C, AD, A44723). A. Habit of tetrasporangial plant. B. Habit of cystocarpic plant. C. Cross section of cystocarp, with cortical rupture on right. D–F. Mychodea australis (D, AD, A44692; E, F, AD, A41802). D. Habit. E. Longitudinal section with the darkly staining central filament and an enlarged auxiliary cell. F. Section of a mature cystocarp with the cortical rupture on the upper side. [B–F as in Kraft 1978.]

Figure 167 image

Figure 167   enlarge

Fig. 167. A–F. Mychodea marginifera (A, AD, A44726, B–E, AD, A44725; F, AD, A44723). A. Habit of a branch with cystocarps. B. Transverse section of a branch. C. Section of cortex with polycarpogonial supporting cells. D. A supporting cell with three carpogonial branches. E. Section of cortex with sunken spermatangial clusters. F. Section of cortex with young and mature tetrasporangia. G–K. Mychodea australis (G, AD, A44695; H, J, A44692; I, AD, A44693). G. Habit of a deep water plant. H. Habit of a shallow water plant. I. Transverse section of a branch. J. Section of cortex with a polycarpogonial supporting cell. K. Section of cortex with sunken spermatangial clusters. [A–K after Kraft 1978.]


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