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Electronic Flora of South Australia Species Fact Sheet

Phacelocarpus complanatus Harvey 1859b: 313; 1863: pl. 252, synop.: xxxiii.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Phacelocarpaceae

Selected citations: J. Agardh 1876: 399. De Toni 1900: 390. Kylin 1932: 51. Searles 1968: 23, fig. 9, pl. 4a.

Thallus (Fig. 133A) medium to dark red-brown, 10–30 (–40) cm high, with a single, terete to slightly compressed stipe 5–20 mm long and 1–3 mm broad, producing several much branched main branches with irregular laterals for 3–4 orders. All branches bearing distichous, compressed, closely alternate, pointed ramuli 500–800 µm long, usually slightly shorter (rarely longer) than the rachis width of 500–800 (–1000) µm, the latter with a slightly raised central midrib. Holdfast discoid-conical, 2–6 mm across; epilithic. Structure uniaxial, developing a prominent axial filament surrounded by short cells, within a thick mass of rhizoids, each axial cell with four periaxial cells, the opposite lateral ones forming the alternate ramuli. Cortex pseudoparenchymatous, inner cells ovoid and 20–30 µm in diameter, outer cells 2–4 µm in diameter and L/D 1–2; refractive cells absent; rhodoplasts discoid, becoming elongate, several per cell.

Reproduction: All reproductive bodies sessile (or cystocarps short stalked) on the upper surface of the ramuli, just below their apices, often twisted to appear on the adaxial margin. Sexual thalli dioecious. Cystocarps (Fig. 133B) 200–400 µm across, bilabiate with an elongate ostiole between the thick pericarp lobes (Fig. 133E), enclosing the carposporophyte with a basal fusion cell producing gonimoblast filaments each with a terminal pair of elongate-ovoid carposporangia 6–9 µm in diameter. Spermatangia in channels in globular nemathecia 200–300 µm across (Fig. 133C).

Tetrasporangia within ovoid to subspherical nemathecia (Fig. 133D) 200–300 µm across, separated by tufts of sterile filaments, 20–30 µm long and 6–10 µm in diameter, zonately divided (Fig. 133F).

Type from Southport, Tas. (Stuart); lectotype in Herb. Harvey, TCD (Alg. Aust. Exsicc. 306).

Selected specimens: Elliston, S. Aust., drift (Womersley, 13.i.1951; AD, A13479). Port Elliot, S. Aust., drift (Womersley, 17.x.1948; AD, A9448). Cape Buffon, S. Aust., 5 m deep (Kildea & Collings, 27.ix.1992; AD, A61766). Cape Northumberland, S. Aust., 15 m deep (Shepherd, 15.xi.1975; AD, A47195 -"Marine Algae of southern Australia" No. 173). Lawrence Rock, Portland, Vic., 24–30 m deep 1.6 km W of Rock (Owen, 2.ix.1971; AD, A39663). Point Roadknight, Vic., drift (Sinkora A1409, 29.xi.1971; AD, A43202). Port Phillip Heads, Vic. (Wilson, 30.v.1891; MEL, 697871).

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

Distribution: Elliston, S. Aust., to Port Phillip Heads, Vic., and around (?) Tasmania.

Taxonomic notes: P. complanatus is similar to P. alatus when sterile though the ramuli are about as long (occasionally slightly longer) than the rachis. It is clearly separated by all reproductive bodies being on the adaxial edge of the ramuli, not on stalks between the ramuli. It appears to be a deep-water species.


AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 - Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)

DE TONI, G.B. (1900). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 2, pp. 387–776. (Padua.)

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. Flora Tasmaniae. Vol. II, pp. 282–320.

HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)

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.

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. 133.

Figure 133 image

Figure 133   enlarge

Fig. 133. Phacelocarpus complanatus (A, C–F, AD, A61766; B, AD, A47195). A. Habit. B. Branch with cystocarps on ramuli. C. Branch with spermatangial nemathecia on ramuli. D. Branch with tetrasporangial nemathecia on ramuli. E. Section of cystocarp across the ostiolar slit. F. Longitudinal section of ramulus with terminal tetrasporangial nemathecium.

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