Electronic Flora of South Australia Species Fact Sheet

Ulothrix subflaccida Wille 1901: 27.

Phylum Chlorophyta – Order Ulotrichales – Family Ulotrichaceae

Selected citations: Lokhorst 1978: 242, figs 18–19.

U. pseudoflacca Wille sensu Womersley 1956: 349.

Thallus of numerous, slender, discrete filaments (Fig. 41A, B), each with a basal, elongate, tapering, rhizoidal holdfast cell, uniform in diameter throughout the length of the filament, (8–) 9–11 (–12) µm in diameter, not or scarcely incised at cross walls. Cells L/B (0.5–) 0.7–1 (–1.3); chloroplast encircling most of the cell (Fig. 41A) and reaching (or almost so) to cross walls, with one pyrenoid; wall thin.

Reproduction: Reproduction unknown in detail for Australian material, though zooids are usually present (Fig. 41C). In Europe (Lokhorst 1978, p. 244) by quadriflagellate zoo(mito)spores, aplanospores and biflagellate isogametes (2–16 per cell), filaments dioecious, and by quadriflagellate zoospores [(1–) 2–4 (–8) per cell] from the unicellular sporophyte stage.

Lectotype from Dröbak, Norway, in UPSV (isotypes in BM, L (920, 13... 380), LD).

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

Distribution: Widely distributed in marine and brackish situations of sheltered to moderate wave action, intertidal.

Taxonomic notes: In southern Australia, known from American River inlet, Kangaroo I., S. Aust., on boats at water line, near jetty (Womersley, 26.viii.1948; ADU, A 9461; 31.viii.1950; ADU, A15399, and 18.vii.1954; ADU, A19779). Port MacDonnell, S. Aust., mid eulittoral on rocks, inside of breakwater (Parsons & Womersley), 5.vi.1982; ADU, A53182). Apollo Bay, Vic. just above bow water-line on boats (Womersley, 13.v.1982; ADU, A53176). There is no significant fresh water dilution at these localities.

The American River inlet material has been checked by Dr G.M. Lokhorst as belonging to U. subflaccida.


LOKHORST, G.M. (1978). Taxonomic studies on the marine and brackish-water species of Ulothrix (Ulotricales, Chlorophyceae) in western Europe. Blumea 24, 191–299.

WILLE, N. (1901). Studien über Chlorophyceen. I-VIII. Nor. videnskakad. Oslo. Math. nat. Kl. 6, 1–46, Plates 1–4.

WOMERSLEY, H.B.S. (1950). The marine algae of Kangaroo Island. III. List of species 1. Trans R. Soc. S. Aust. 73, 137–197.

WOMERSLEY, H.B.S. (1956). A critical survey of the marine algae of southern Australia. I. Chlorophyta. Aust. J. mar. freshw. Res. 7, 343–383.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustration in Womersley Part I, 1984: FIG. 41 A-C.

Figure 41 image

Figure 41   enlarge

Fig. 41. A–C. Ulothrix subflaccida. A. Upper part of filament (ADU, A 15399). B. Base of filament with elongate rhizoidal cell (ADU, A15399). C. Reproductive cells with zooids (ADU, A53176). D,E. Uronema marina. D. Filament with upper cell containing zooids (ADU, A51119). Dl. Terminal cell of young filament (ADU, A31827). E. Filament (ADU, A31827). F. Entocladia viridis. Thallus epiphytic on Cladophora rhizoclonioidea (ADU, A52871). G,H. Pilinia novae-zelandiae. G. Thallus on Sargassum, with terminal sporangia on short erect filaments (ADU, A32003). H. Part of a long erect filament with lateral sporangia (ADU, A50870).

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