Electronic Flora of South Australia Species Fact Sheet
Phylum Phaeophyta – Order Sphacelariales – Family Stypocaulaceae
Selected citations: Sauvageau 1914: 457, fig. 90. Womersley 1967: 205.
Thallus (Fig. 60B) medium to dark brown, (5–) 8–16 cm long, with one to several axes from a small discoid base 0.5–1.5 mm across; axes dark brown to almost black, smooth, often denuded of laterals below, and above bearing numerous alternate, dense, fasciculate tufts along the main lateral branches (Fig. 60B); epilithic. Branching (Fig. 61A,B) of several orders, radial or often subdistichous near the apices with laterals every 2–4 segments, with lesser laterals determinate and tapering to a point over their last few segments; laterals with a single, large, inner cell (later subdivided) and a single-layered cortex of elongate cells which divide transversely, and usually again, to give a row of four cells per segment; loose descending rhizoids absent, but appressed rhizoidal secondary cortication developing at base of lateral tufts: phaeophycean hairs in clusters in axils of laterals (Fig. 6IB), lost from older parts. Axes (Fig. 6IC) (300–) 500–800 µm in diameter, with a smooth-surfaced secondary cortex of cells which enlarge and on oldest axes cut off radially chains of smaller cells forming an outer secondary cortex; uncorticated laterals 80–120 µm in diameter with segments L/B (0.5–) 0.8–1.0; determinate laterals (Fig. 61A,D) 70–80 µm in diameter for most of their length with segments L/B 0.6–1.0, shorter near the tips.
Reproduction: Unilocular sporangia (Fig. 61D,E) 1–2 (–3) in axils of laterals, subtended by two, opposite, simple or once (–2) branched bracts, usually inwardly curved, positioned at right angles to the axis and lateral; sporangia with a short, 1–3 celled pedicel, sub-spherical, (50–) 70–90 (–105) µm in diameter. Sexual plants (Fig. 61F) with small mixed clusters of macro-and microgametangia borne similarly to the sporangia but subsessile on a small, multicellular pad; macrogametangia subspherical, 60–120 µm in diameter, with loculi 4–6 µm across; microgametangia subspherical to ovoid, (80–) 100–14012m across, with loculi 2–4 µm across.
Type from "Süd-Australien"; in KIEL.
Selected specimens: Geographe Bay, W. Aust. (1879; MEL, 15788). Venus Bay, S. Aust., drift (Womersley, 12.ii.1954; ADU, A19484, sporangial). Investigator Strait, S. Aust., 25 m deep, 35°18'S, 137°17'E (Watson, 15.i.1971; ADU, A39339, sporangial). Pennington Bay, Kangaroo 1., S. Aust, drift (Womersley, 8.i.1947; ADU, A4383, sexual). Victor Harbor, S. Aust., drift (Parsons, 10.i.1970; ADU, A35030). Kingston, S. Aust., drift ( Womersley, 27.v.1963: ADU, A26395, sexual). Lorne, Vic., drift ( Womersley, 23.i.1967; ADU, A31528).
Distribution: From Geographe Bay, W. Aust., around southern Australia to Lorne, Vic., and N.W. Tasmania (Sauvageau 1914. p. 458).
Taxonomic notes: Phloiocaulon spectabile is typically a deeper water alga, known from the drift and to 25 m deep; specimens from shaded upper sublittoral pools are usually more densely tufted and sterile. It appears to be more widespread than P. foecundum on southern Australian coasts, differing from the latter species in its more open spikes with the reproductive organs visible and confined to the axils of laterals.
REINKE, J. (1890) Uebersicht der bisher bekannten Sphacelariaceen. Ber. Deutsch. Bot. Ges. 8, 201–215.
REINKE, J. (1891). Beiträge zur vergleichenden Anatomie und Morphologie der Sphacelariaceen. Bibl. Bot. 23, 1–40, Plates 1–13.
WOMERSLEY, H.B.S. (1967). A critical survey of the marine algae of southern Australia. II. Phaeophyta. Aust. J. Bot. 15, 189–270.
The Marine Benthic Flora of Southern Australia Part II complete list of references.
Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
©Board of the Botanic Gardens and State Herbarium, Government of South Australia
Illustrations in Womersley Part II, 1997: FIGS 60B, 61.
Figure 60 enlarge
Fig. 60. A. Halopteris paniculata (ADU, A13396). B. Phloiocaulon spectabile (ADU, A35030). C. Phloiocaulon foecundum (ADU, A22883). D. Cladostephus spongiosus (ADU. A55543).
Figure 61 enlarge
Fig. 61. Phloiocaulon spectabile (A–E, ADU, A19484; F, ADU, A4383). A. Branching pattern. B. Upper branches with axillary phaeophycean hairs and two determinate laterals. C. Transverse section of axis with extensive secondary cortex. D. Sporangial branch with opposite bracts in the axils of laterals. E. Detail of sporangia and bracts. F. Branch of sexual plant with macro- and microgametangia.
State Herbarium of South Australia