Electronic Flora of South Australia Species Fact Sheet

Ralfsia verrucosa (Areschoug) J. Agardh 1848: 62.

Phylum Phaeophyta – Order Chordariales – Family Ralfsiaceae

Selected citations: Fletcher 1978: 373 et seq., figs 1, 2, 5, 6, 13, 14, 23, 24. Hamel 1935: 106, fig. 26A,B. Jaasund 1964: 131, fig. 2. Kormann & Sahling 1977: 118, fig. 62. Kylin 1947: 44, fig. 38A,B. Lindauer et al. 1961: 211, fig. 38. Tanaka & Chihara 1980b: 227, figs 1A, 2A, B. Taylor 1957: 135, pl. 11 figs 1,2.

Thallus (P1.1 fig. 1; Fig. 15B) medium brown when young, becoming dark brown when older and thicker, a few mm to 5 cm across and (100–) 150–400 (–500) µm thick, crustose and not gelatinous, surface smooth to slightly verrucose when older, margin circular when young but becoming irregular with age, often slightly concentrically zoned, tightly adherent to the rock, shell or wood substrate, often overgrowing older thalli. Basal layer of radiating filaments, without rhizoids, slightly assurgent at the several-layered margin and moderately to strongly radially assurgent within the margin (Fig. 19A) with cells 4–10 (–12) µm across and L/B 2–6 (–8). Erect filaments (Fig. 19A,B) continuing from assurgent filaments, closely adjacent and not separating readily under pressure, with cells 3–8 (–10) µm in diameter and L/B 1–1.5 (–2). Growth by divisions of apical cells of basal and erect filaments. Cells with a single, often irregularly shaped phaeoplast and several to numerous, usually prominent, physodes (Fig. 19C). Phaeophycean hairs (Fig. 19A) in clusters, arising from basal layer or lower assurgent filaments.

Reproduction: Reproduction by plurilocular sporangia (Fig. 19B) forming small to spreading surface sori, each sporangium uniseriate (rarely with occasional biseriate locules) from an erect filament, 50–100 µm long with 8–14 (–20) locules and 3–5 (–8) µm in diameter, with a terminal sterile cell. Unilocular sporangia (Fig. 19A,C) in surface sori, each accompanied by a cylindrical to slightly clavate paraphysis 80–120 µm and 6–8 cells long; sporangia elongate-ovoid to clavate, 70–90 µm long and 18–26 µm in diameter.

Type from Bahusia, Norway.

Selected specimens: (plurilocular sporangial unless otherwise stated). Cowaramup Bay, W. Aust., low eulittoral on Balanus (Hodgkin, 11.xi.1956; ADU, A21531). Point Sinclair, S. Aust., low to mid eulittoral ( Womersley, 26.i.1951 and 9.ii.1954; ADU, A15059 and A19607 resp.). Denial Bay, S. Aust., mid eulittoral (Womersley, 23.i.1951; ADU, A15055). Wittelbee Point, S. Aust., low eulittoral pool (Womersley, 22.i.1951; ADU, A15189). Edithburgh, S. Aust., 1–2 m deep in swimming pool (Womersley, 18.ix.1981; ADU, A52998). Port Stanvac, S. Aust., mid eulittoral (Dowd, 25.xi.1981; ADU, A52817). Port Noarlunga, S. Aust., mid eulittoral in part shade (Womersley, 3,xii.1986; ADU, A57427). Pennington Bay, Kangaroo I., S. Aust., lower eulittoral ( Womersley, 28.viii.1950; ADU, A15364-unilocular sporangia). Ballast Head, Kangaroo I., S. Aust., mid eulittoral (Womersley, 3.ii.1956; ADU, A20301-unilocular sporangia). Antechamber Bay, Kangaroo I., S. Aust., mid-eulittoral (Womersley, 8.i.1950; ADU, Al2921). Robe, S. Aust., mid eulittoral (Womersley, 20.xii.1953; ADU, A19140). Bridgewater Bay, Vic., lower eulittoral (Womersley, 14.iv.1959; ADU, A22634). Port Arthur, Tas., lower mid eulittoral (Cribb 128.4, 9.ii.1951; ADU, A21054). Cape Forestier, Tas., pool (Bennett 4, 21.vi.1954; ADU, A19826). Kurnell, Botany Bay, N.S.W., lower eulittoral (Womersley, 26.xii.1962; ADU, A26472).

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

Distribution: Widespread on cold temperate to subtropical coasts, probably throughout the world.

All along southern Australia, from at least Cowaramup Bay, W.Aust., to Broken Bay, N.S.W. and around Tasmania.

Taxonomic notes: The southern Australian species seems indistinguishable from the European R. verrucosa, though usually forming thinner crusts with a less verrucose surface. Hollenberg in Smith (1944, p. 95) separated the Pacific N.American species as R. pacifica, and distinguished it (Hollenberg 1969, p. 296) from R. verrucosa in that the latter frequently has overgrown multistratose thalli and the plurilocular sporangia of R. pacifica are regularly uniseriate; however, Hollenberg (1969, fig. 17) and Abbott & Hollenberg (1976, fig. 135), illustrate two partly biseriate plurilocular sporangia. The Australian specimens occasionally have overgrown thalli and rarely have partly biseriate plurilocular sporangia, and it seems best to refer them to the widespread R. verrucosa, from which R. pacifica is probably not distinct. R. australis Skottsberg (1921, p. 20, fig. 8n) from the Falkland Islands is also closely related but differs in lacking hairs.

Most southern Australian specimens appear to belong to this one species, but others probably do occur. The Tasmanian specimens usually have a thicker thallus with filaments of somewhat greater diameter than those on the mainland coast.


ABBOTT, I.A. & HOLLENBERG, G.J. (1976). Marine Algae of California. (Stanford Univ. Press: Stanford.)

AGARDH, J.G. (1848). Species, Genera et Ordines Algarum. Vol. 1. (Gleerup: Lund.)

FLETCHER, R.L. (1978). Studies on the family Ralfsiaceae (Phaeophyta) around the British Isles. In Irvine, D.E.G. & Price, J.H. (Eds), Modern approaches to the taxonomy of red and brown algae. Systematics Association Special Volume 10, 371–388. (Academic Press: London.)

HAMEL, G. (1935). Phéophycées de France. Fasc. II, pp. 81–176. (Paris.)

HOLLENBERG, G.J. (1969). An account of the Ralfsiaceae (Phaeophyta) of California. J. Phycol. 5, 290–301.

JAASUND, E. (1964). Marine algae from northern Norway. III. Bot. Mar. 6, 129–133.

KYLIN, H. (1947). Die Phaeophyceen der Schwedischen Westkiiste. Acta Univ. lund. N.F. Avd. 2, 43(4), 1–99, Plates 1–18.

LINDAUER, V.W., CHAPMAN, V.J. & AIKEN, M. (1961). The marine algae of New Zealand. II. Phaeophyceae. Nova Hedwigia 3, 129–350, Plates 57–97.

SKOTTSBERG, C. (1921). Botanische Ergebnisse der Schwedischen Expedition nach Patagonien und dem Feuerlande, 1907–1909. VIII. Marine Algae. I. Phaeophyceae. K. Svenska Vetenskapsakad. Handl. 61(11), 1–56.

SMITH, G.M. (1944). Marine Algae of the Monterey Peninsula, California. (Stanford.)

TANAKA, J. & CHIHARA, M. (1980b). Taxonomic study of the Japanese crustose brown algae (2). Ralfsia (Ralfsiaceae, Ralfsiales)(Part I). J. Jap. Bot. 55, 225–236.

TAYLOR, W.R. (1957). Marine algae of the Northeastern coast of North America. Rev. Edn. (Univ. Mich. Press: Ann Arbor.)

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustration in Womersley Part II, 1997: PLATE 1 fig. 1. FIGS 15B, 19 A–C.

Plate 1 image

Plate 1   enlarge

PLATE 1 fig. 1. Ralfsia verrucosa at Port Noarlunga, S. Aust. (ADU, A57427).
fig. 2. Dictyopteris muelleri. An upper sublittoral plant photographed on rock, Robe, S. Aust.

Disclaimer Copyright Disclaimer Email Contact:
State Herbarium of South Australia
Government of South Australia Government of South Australia Department of Environment, Water and Natural Resources