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Electronic Flora of South Australia Species Fact Sheet

Ptilocladia crouanioides (Sonder) Womersley, comb. nov.

Phylum Rhodophyta – Order Ceramiales – Family Ceramiaceae – Tribe Crouanieae


Dasya crouanioides Sonder 1853: 703; 1881: 36. J. Agardh 1852: 1239; 1890a: 113. Harvey 1859b: 304. Kützing 1864: 32, pl. 89d-f.

Thallus (Fig. 23A) medium red-brown, 2–8 cm high, erect, irregularly much branched, branches terete with distinct and slightly separated whorls of whorl -branchlets near apices (Fig. 23B), closely adjacent in mid thallus and separated on lower corticated parts, branches 500–850 µm in diameter below, tapering to 180–280 in diameter just below apices. Holdfast small, rhizoidal; epiphytic on Posidonia, Amphibolis or coralline or other algae. Structure. Axes with short apical cells 6–10 µm in diameter and L/D 1–1.2, axial cells in young branches 15–30 µm in diameter and L/D 2–3, increasing to 200–350 µm in diameter and L/D 1.5–2 in lower thallus, becoming corticate 10–20 cells below apices with compact cortical filaments (Fig. 23E) within the axial cell sheath, with numerous branched anticlinal filaments. Lateral branches originating from axial cells. Whorl-branchlets 4 per axial cell, 140–250 µm and 6–8 cells long, di- (or tri-) chotomously branched, basal cells 20–30 µm in diameter and L/D 1–2, tapering to terminal cells 4–7 µm in diameter and L/D 1.5–2.5, often with hairs; gland cells (Fig. 23C) usually numerous near branch apices, pyriform to subspherical. Cells uninucleate; rhodoplasts discoid, ribbon like in larger cells.

Reproduction: Gametophytes dioecious. Procarps appear to be borne on mid cells of whorl-branchlets, with a supporting cell bearing a 4-celled carpogonial branch. Post-fertilization the auxiliary cell produces 1–3 gonimolobes 50–100 µm across of ovoid carposporangia 9–12 µm in diameter, loosely surrounded by whorl-branchlets (Fig. 23D, E). Spermatangia unknown.

Tetrasporangia occur on mid cells of whorl-branchlets, sessile, subspherical, 20–30 µm in diameter, tetrahedrally divided.

Type from Tasmania (Stuart); holotype in MEL, 8458.

Selected specimens: Waldegrave I., S. Aust., 22 m deep (Shepherd, 23.x.1970; AD, A37411). Investigator Strait, S. Aust., 31 m deep (Watson, 24.i.1971; AD, A38377) and 23 m deep (Watson, 15.i.1971; AD, A41034). Tiparra Reef, Spencer Gulf, S. Aust., on Amphibolis, 11 m deep (Shepherd, 31.x.1970; AD, A37720, A37692). Troubridge Light, Edithburg, S. Aust., 17 in deep (Shepherd, 4.ii.1969; AD, A33428). Sellicks Beach, S. Aust., on Haliptilon, drift (O'Leary, 12.vi.1993; AD, A62191). Queenscliff, Vic., drift (Norris, 21.i.1963; AD, A26310). Walkerville, Vic., drift (Sinkora A1653, 23.ii.1972; AD, A43094 and Sinkora A2087, 26.ii.1975; AD, A48322). Montagu, NW Tas. (Perrin, Mar. 1950; AD, A49639). Rocky Cape, N Tas., drift (Gordon, 18.i.1966; AD, A29965).

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

Distribution: Waldegrave I., S. Aust., to Walkerville, Vic., and N Tasmania.

Taxonomic notes: P. crouanioides is similar to P. vestita but is generally slenderer, with whorls of whorl-branchlets separated throughout most of the thallus, and has distinctly smaller tetrasporangia than the latter. The procarp situation needs further study from fresh collections.


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

AGARDH, J.G. (1890a). Till algernes systematik. Acta Univ. lund. 26(3), 1–125, Plates 1–3.

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. III. Flora Tasmaniae. Vol. II, pp. 282–343, Plates 185–196. (Reeve: London.)

KÜTZING, F.T. (1864). Tabulae Phycologicae. Vol. 14. (Nordhausen.)

SONDER, O.W. (1853). Plantae Muellerianae. Algae. Linnaea 25, 657–709.

SONDER, O.W. (1881). In Mueller, F., Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae, pp. 1–42, 105–107. (Melbourne.)

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

Author: E.M. Wollaston & H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia

Illustration in Womersley Part IIIA, 1998: FIG. 23 A–E.

Figure 23 image

Figure 23   enlarge

Fig. 23. A–E. Ptilocladia crouanioides (A, AD, A48322; B, AD, A38377; C, AD, A37692; D, E, AD, A62191). A. Habit. B. Young branches. C. Young branch with gland cells on whorl-branchlets. D. Young branches with carposporophytes. E. Older corticated axis with young lateral bearing a carposporophyte. F. Gulsonia annulata (AD, A20059). Habit.

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