Electronic Flora of South Australia Species Fact Sheet

Stenocladia australis (Sonder) Silva 1950: 269.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Nizymeniaceae

Selected citations: Searles 1968: 35, fig. 16, pl. 7. Womersley 1971b: 201.

Synonyms

Ginannia australis Sonder 1845: 57.

Halymenia australis (Sonder) Sonder 1848: 173.

Scinaia australis (Sonder) Trevisan 1848: 105.

Euctenodus australis (Sonder) Kützing 1849: 770.

Phacelocarpus australis (Sonder) J. Agardh 1852: 649.

Areschougia conferta Harvey 1860b: pl. 166.

Stenocladia conferta (Harvey) J. Agardh 1872: 45 (with vars cliftoni and harveyi). Kylin 1932: 50, fig. 13.

Stenocladia corymbosa J. Agardh 1876: 440.

Stenocladia cliftonii (J. Agardh) J. Agardh 1876: 440.

Stenocladia harveyana J. Agardh 1876: 440.

Stenocladia sonderiana J. Agardh 1876: 441.

Thallus (Fig. 138A) erect, medium red to dark red-brown, 5–15 (–20) cm high, much branched from the margins, branches compressed, linear, (0.7–) 1–2 mm broad, basally constricted and with rounded apices. Holdfast discoid, 2–6 mm across, with several terete to slightly compressed stipes 2–10 mm long and 0.5–2 mm in diameter; epilithic. Structure uniaxial (Fig. 138C), with four periaxial cells, the lateral two more strongly developed, and a prominent axial filament 60–100 µm in diameter throughout the thallus, densely surrounded by thick-walled rhizoids 5–9 µm in diameter. Cortex pseudoparenchymatous with angular, closely packed cells, inner ones 15–30 µm in diameter, outermost 2–3 (–5) µm in diameter and L/D 1–1.5. Rhodoplasts discoid to elongate, few to numerous per cell.

Reproduction: Sexual thalli dioecious. Procarps formed in tufts of filaments on the branch margins, associated with extension of a lateral vegetative filament, and with the outer filaments of a tuft cutting off cells laterally from the upper 4–5 cells. Auxiliary cell intercalary, with one to three 3-celled carpogonial branches, post-fertilization connecting filament single and uniting with the auxiliary cell which produces a single gonimoblast initial and later a large fusion cell with radiating gonimoblast filaments bearing rows of 2–4 subspherical to ovoid carposporangia 6–9 µm in diameter. Cystocarps (Fig. 138B) subspherical on the branch margins, basally constricted, 400–700 µm in diameter, with a thick pericarp and prominent depressed ostiole. Spermatangia on branched upper laterals of uniseriate filaments (Fig. 138E, F) 6–9 µm in diameter, cells L/D 1.5–2, in tufts on the flat surface of branches.

Tetrasporangia unknown.

Type from Nov. Holl. occid. (Preiss); holotype in MEL, 44636.

Selected specimens: Geraldton, W. Aust. (MEL, 44851–44855). Flat Rocks, 40 km S of Geraldton, W. Aust., drift (Mitchell, 17.ix.1966; AD, A30989, A30990). Garden I., W. Aust., under reef ledges, sublittoral (Chittleborough, 21.ix.1966; AD, A31196). Pearson Is, S. Aust., 50 m deep (Shepherd, 9.i.1969; AD, A33874). Stenhouse Bay, S. Aust., drift (Womersley, 9.iv.1950; AD, A13239). Vivonne Bay, Kangaroo I., S. Aust., drift (Womersley, 14.i.1948; AD, A6920, A6922). Seal Bay, Kangaroo I., S. Aust., drift (Womersley, 22.xi.1968; AD, A32955 -"Marine Algae of southern Australia" No. 85). Robe, S. Aust., 3–6 m deep (Baldock, 15.v.1967; AD, A31484). 1.3 km off Middle Point, Cape Northumberland, S. Aust., 13 m deep (Shepherd, 19.iii.1974; AD, A44934). Point Lonsdale, Vic. (Hansen, Jan. 1955; AD, A20452). Port Phillip Heads, Vic. (Wilson, 10.x.1891; MEL, 44617). Marrawah, Tas. (Perrin, Mar. 1950; BM).


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

Distribution: Geraldton, W. Aust., to Port Phillip Heads, Vic., and NW Tasmania.

Taxonomic notes: Stenocladia australis is somewhat similar in habit to Nizymenia australis, but is more erect with slenderer branches and has a prominent axial filament throughout the thallus. It is essentially confined to deep water on rough-water coasts.

Searles (1968, fig. 16B, C) illustrated what he considered were male filaments in marginal tufts surrounding procarps. Such filaments (Fig. 138C, D) also occur on AD, A6922, but procarps were not observed. However, AD, A30990 shows surface tufts of filaments with upper laterals cutting off spermatangia (Fig. 138E, F) and it seems doubtful that the structures illustrated by Searles are the spermatangia. Clearly, further studies of S. australis are needed.

References:

AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)

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.)

HARVEY, W.H. (1860b). Phycologia Australica. Vol. 3, Plates 121–180. (Reeve: London.)

KÜTZING, F.T. (1849). Species Algarum. (Leipzig.)

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

SEARLES, R.B. (1968). Morphological studies of red algae of the order Gigartinales. Univ. Calif Pubis Bot. 43, vi + 1–86, Plates 1–12.

SILVA, P.C. (1950). Generic names of algae proposed for conservation. Hydrobiologia 2, 252–280.

SONDER, O.G. (1845). Nova Algarum genera et species, quas in itinere ad oras occidentales Novae Hollandiae, collegit L. Preiss, Ph.Dr. Bot. Zeit. 3, 49–57.

SONDER, O.W. (1848). Algae. In Lehmann, C., Plantae Preissianae. Vol. 2, pp. 161–195. (Hamburg.)

TREVISAN, V.B.A. (1848). Saggio di una monografia delle alghe cocotalle. (Padova.)

WOMERSLEY, H.B.S. (1971b). The relationships of Nizymenia and Stenocladia (Gigartinales, Rhodophyta). Phycologia 10, 199–203.

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.


Illustration in Womersley Part IIIA, 1994: FIG. 138.

Figure 138 image

Figure 138   enlarge

Fig. 138. Stenocladia australis (A, AD, A32955; B–D, AD, A30989; E, F, AD, A30990). A. Habit. B. Longitudinal section of cystocarp (not through ostiole). C. Transverse section of thallus with marginal cluster of filaments of unknown function. D. Detail of marginal filaments. E. Surface cluster of spermatangial filaments. F. Detail of spermatangial filaments.


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