Electronic Flora of South Australia Species Fact Sheet

Audouinella secundata (Lyngbye) Dixon in Parke & Dixon 1976: 590.

Phylum Rhodophyta – Class Florideophyceae – Order Acrochaetiales – Family Acrochaetiaceae

Selected citations: Garbary 1987: 166.


Callithamnion daviesii var. secundatum Lyngbye 1819: 129, pl. 41 fig. B4–6.

Acrochaetium secundatum (Lyngbye) Nägeli 1861: 405. Abdel-Rahman & Bidoux 1989: 235, figs 1–4. Lee 1987: 36, fig. 18. Stegenga 1985: 305, figs 10, 11.

Colaconema secundatum (Lyngbye) Woelkerling 1973a: 94, figs 7, 8; 1973b: 575, figs 77–83.

Audouinella tenuissima (Collins) Garbary 1979b: 490; 1987: 182.

Acrochaetium tenuissimum (Collins) Papenfuss 1945: 319. Stegenga 1985: 305, fig. 12?

Colaconema tenuissimum (Collins) Woelkerling 1971: 51, fig. 21.

Acrochaetium subsimplex Levring 1953: 473, figs 10A–D, 11.

Thallus (Fig. 8A) epiphytic, caespitose, 1–4 mm high; original spore dividing into (2–) 3 cells, recognizable in young but not older thalli. Prostrate system (Fig. 8A) pseudoparenchymatous at first but soon producing short, distinct, more or less confluent filaments. Erect filaments (Fig. 8A, B) simple or sparingly and irregularly branched, tapering slightly towards the apices. Cells cylindrical (Fig. 8B, C), (4–) 6–8 (–10) µm in diameter and (15–) 24–40 (–50) µm long, L/D 3–6 (–8); each cell containing a parietal laminate (sometimes with slight arms) or stellate rhodoplast (Fig. 8C) with one pyrenoid (often obscure). Hairs terminal and pseudolateral, up to 300 µm long.

Reproduction: Monosporangia (Fig. 8B) ovoid, 9–15 µm in diameter and 18–24 µm long, solitary, sessile or rarely stalked, scattered on the erect filaments or occasionally terminal.

Gametophytes with a single basal cell, dioecious (Abdel-Rahman & Bidoux 1989: 241, figs 2, 4).

Tetrasporophyte with a monostromatic basal disc, tetrasporangia cruciately divided (Abdel-Rahman & Bidoux 1989: 239, fig. 3).

Type from Kvivig, Faroe Is, on "Conferva rupestris"; in C.

Selected specimens: Glenelg R. mouth, Discovery Bay, Vic., on Zostera muelleri (Beauglehole, 26.i.1952; AD, A21725). Musselroe Bay, Tas., on seagrass (Zostera?) (Levring, 7.ii.1948; AD, A19846, isotype of Acrochaetium subsimplex Levring).

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

Distribution: Widespread in the temperate and arctic N. Atlantic; western tropical Africa; South Africa; California; Korea.

In southern Australia, from the Glenelg R. mouth, Vic., and Musselroe Bay, Tas. (on Zostera?).

Taxonomic notes: Woelkerling (1973b, p. 581) considered the types of A. secundata, A. virgatula and A. tenuissima to be conspecific, as did Schneider & Searles (1991, p. 209), and the above Australian specimens are very similar to isotype material of A. tenuissima. Many illustrations of A. secundata show more highly developed secund branching and more distinct rows of monosporangia and some authors [e.g. Dixon & Irvine (1977b) and Stegenga (1985, p. 305)] have kept these species separate. Stegenga considers that A. secundata is confined to the Atlantic Ocean, but his figures of A. secundata and A. tenuissima are very similar and the differences in the prostrate system and monosporangium size are probably infraspecific. The rhodoplasts are usually described as stellate in A. secundata and laminate in A. tenuissima (see however Stegenga & Kemperman 1983, p. 73); Australian specimens have essentially laminate rhodoplasts which in some cells possess arms and appear stellate.


ABDEL-RAHMAN, M.H. & BIDOUX, C. (1989). Le cycle de développement de l'Acrochaetium secundatum (Rhodophyceae, Acrochaetiales). Cryptogamie, Algol. 10, 235–245.

DIXON, P.S. & IRVINE, L.M. (1977b). Seaweeds of the British Isles. Vol. 1, Rhodophyta. Part I, Introduction, Nemaliales, Gigartinales. [British Museum (N.H.): London.]

GARBARY, D.J. (1979b). Numerical Taxonomy and generic circumscription in the Acrochaetiaceae (Rhodophyta). Bot. Mar. 22, 477–492.

GARBARY, D.J. (1987). The Acrochaetiaceae (Rhodophyta): An annotated bibliography. Bibl. Phycol. 77, 1–267.

LEE, Y.P. (1987). Taxonomy of the Rhodochortonaceae (Rhodophyta) in Korea. Korean J. Phycol. 2, 1–50.

LEVRING, T. (1953). The marine algae of Australia. I. Rhodophyta: Goniotrichales, Bangiales and Némalionales. Arkiv för Bot. Ser. 2, 2, 457–530.

LYNGBYE, H.CH. (1819). Tentamen Hydrophytologiae Danicae. (Copenhagen.)

NÄGELI, C. (1861). Beitrage zur Morphologie and Systematik des Ceramiaceae. Sber. bayer. Akad. Wiss. Jb., 1861, 1, 297–415, Plate 1.

PAPENFUSS, G.F. (1945). Review of the Acrochaetium-Rhodochorton complex of the red algae. Univ. Calif Pubis Bot. 18, 299–334.

PARKE, M. & DIXON, P.S. (1976). Check-list of British marine algae - third revision. J. mar. biol. Ass. U.K. 56, 527–594.

SCHNEIDER, C.W. & SEARLES, R.B. (1991). Seaweeds of the Southeastern United States. (Duke Univ. Press: Durham.)

STEGENGA, H. & KEMPERMAN, T.C.M. (1983). Acrochaetiaceae (Rhodophyta) new to the Costa Rican Atlantic flora. Brenesia 21, 67–91.

STEGENGA, H. (1985). The marine Acrochaetiaceae (Rhodophyta) of southern Africa. S. Afr. J. Bot. 51, 291–330.

WOELKERLING, W.J. (1971). Morphology and taxonomy of the Audouinella complex (Rhodophyta) in southern Australia. Aust. J. Bot. Suppl. 1, 1–91.

WOELKERLING, W.J. (1973a). The Audouinella complex (Rhodophyta) in the western Sargasso Sea. Rhodora 75, 78–101.

WOELKERLING, W.J. (1973b). The morphology and systematics of the Audouinella complex (Acrochaetiaceae, Rhodophyta) in northeastern United States. Rhodora 75, 529–621.

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

Author: W.J. Woelkerling & 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.

Illustration in Womersley Part IIIA, 1994: FIG. 8 A–C.

Figure 8 image

Figure 8   enlarge

Fig. 8. A–C. Audouinella secundata (A, B, AD, A21725; C, AD, A19846). A. Branching pattern, with prostrate system and erect filaments with monosporangia. B. Upper branches with monosporangia. C. Cells with rhodoplasts and a monosporangium. D–J. Audouinella simplex (D, E, I, AD, A32249; F–H, J, AD, A32233). D. Branching pattern, with unicellular base, erect filaments and monosporangia. E. Prostrate system of (presumed) tetrasporophyte. F. Basal cell and lower filaments of gametophyte. G, H. Filaments with stalked monosporangia. I. Cells (all from one filament) showing variation in rhodoplast form. J. Branch with spermatangia. [F–J after Woelkerling 1971.]

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