Electronic Flora of South Australia Species Fact Sheet

Audouinella unifila (Jao) Woelkerling 1973b: 563, figs 44,45.

Phylum Rhodophyta – Class Florideophyceae – Order Acrochaetiales – Family Acrochaetiaceae

Selected citations: Garbary 1987: 189.

Synonyms

Acrochaetium unifilunt Jao 1936: 239, p1. 10 figs 26–32. (NON Levring 1953: 472).

Kylinia australis Levring 1953: 487, fig. 21A–G.

Audouinella australis (Levring) Woelkerling 1971: 9,25, figs 4,5.

Thallus (Fig. 12A–E) epiphytic on larger Audouinella species or filamentous algae, (15–) 40–100 (–350) µm high; original spore (Fig. 12B, D, F) persisting as a hemispherical to pyriform unicellular base appressed to the substrate, 6–9 µm in diameter and 7–12 µm long, rarely dividing to form a two-celled prostrate system or occasionally becoming obscured by the erect filaments. Erect filaments (Fig. 12B, D, E) usually 1–3, procumbent to semi-upright or occasionally coiling about the host, simple or with a few irregularly arranged laterals. Cells (Fig. B, D, E) cylindrical, 3–6 (–8) µm in diameter and 5–25 µm long, L/D 1–5, each cell containing a single parietal lobate rhodoplast (Fig. 12D, E) with one pyrenoid (often obscure). Terminal hairs up to 75 µm long occur.

Reproduction: Monosporangia (Fig. 12B, D) ovoid, 4–6 µm in diameter and 6–10 µm long, terminal or lateral, single or rarely in pairs, sessile or occasionally on 1–2-celled stalks, scattered or occasionally restricted to the lower portions of the plants.

Thalli dioecious. Carpogonia (Fig. 12E) terminal or lateral, sessile or stalked; immediate post-fertilization stages unknown. Mature carposporophytes (Fig. 12F) consisting of several short gonimoblast filaments bearing terminal carposporangia, each 5–7 µm in diameter and 8–12 µm long. Spermatangia (Fig. 12B) globose, 2–3 µm in diameter, terminal or rarely lateral in groups of 1–3, sessile on vegetative filaments.

Tetrasporangia unknown.

Type from Massachusetts, U.S.A.; holotype in MICH (see Woelkerling 1973b, p. 564).

Selected specimens: Head of the Great Australian Bight, S. Aust., on Audouinella daviesii on Amphibolis antarctica, drift (Woelkerling, 4.xi.1968; AD, A32923). Venus Bay, S. Aust., on A. daviesii on Amphibolis sp., drift (Womersley,12.ii.1954; AD, A32110). Stanley Beach, Kangaroo I., S. Aust., on A. daviesii on Lenormandiopsis latifolia, drift (Womersley, 7.ii.1956; AD, A32119 and 27.i.1957; AD, A32112). Pennington Bay, Kangaroo I., S. Aust., on A. daviesii on Polycerea nigrescens, drift (Womersley, 7.i.1947; AD, A31373, isotype of A. australis). Marino, S. Aust., on A. daviesii on Posidonia sp., drift (Womersley, 21.v.1953; AD, A32111). Robe, S. Aust., on A. daviesii on Posidonia coriacea, drift (Woelkerling, 19.viii.1966; AD, A32100).

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

Distribution: Massachusetts, U.S.A.; France.

In southern Australia, from the Head of the Great Australian Bight to Robe, S. Aust.

Taxonomic notes: Woelkerling (1973b, p. 565) has placed Audouinella australis (type from Pennington Bay, S. Aust.) in synonymy with A. unifila, as he suspected previously (Woelkerling 1971, p. 26).

A. unifila is a common, minute, epiphyte on Audouinella daviesii, which is common on Amphibolis, but it is also known on A. caespitosa and Dasya extensa. It is easily overlooked and probably much more widely distributed.

References:

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

JAO, C.-C. (1936). New Rhodophyceae from Woods Hole. Bull. Torrey Bot. Club 63, 237–257.

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

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. (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. 12 A–F.

Figure 12   enlarge

Fig. 12. A–F. Audouinella unifila (A, E, AD, A32110; B–D, F, AD, A31373; all shown on host cells). A. Sporelings. B. Thallus with monosporangia and spermatangia. C. Mature thallus coiled around host. D. Mature erect thallus with monosporangia; three cells shown with rhodoplasts, one with a pyrenoid. E. Thallus with four carpogonia; two cells shown with rhodoplasts. F. Thallus with a carposporophyte. G–M. Audouinella microscopica (G–L, AD, A32250; M, AD, A19855). G–K. Thalli with monosporangia, showing variation within a single population. L. Thallus with hairs, monosporangia, and four cells shown each with a rhodoplast and pyrenoid. M. Mature thallus with denser branching. [A–I, K–M after Woelkerling 1971.]

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