Electronic Flora of South Australia Species Fact Sheet

Myriodesma harveyanum Nizamuddin & Womersley 1967: 377, pls 70B, 73 fig. 4.

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae


M. latifolium sensu Nizamuddin 1962d: 68–73, figs 2,5, 15–18, 24,38, 41–47, 54.

Thallus (Fig. I 53A) medium to dark brown, 15–30 cm long, with several complanately branched fronds from the branched stipe. Holdfast discoid-conical but split or lacerate, 5–15 (–20) mm across; epilithic. Stipe 1–8 cm long, with 1–5 di- or trichotomies at intervals of 1–3 (–4) cm, each 2–4 (–6) mm in diameter. Fronds 10–25 cm long, pinnate, becoming bipinnate, alternately branched with lower branches 5–8 (–10) mm broad and terminal branches (Fig. 156A) 3–5 mm broad, serrate, usually slightly constricted basally; midrib slight below, absent above. Growth from a three-sided apical cell in an apical depression. Structure of fronds 0.7–1 mm and 20–30 cells thick, with a slender, central medulla of elongate cells and a cortex of isodiametric cells with an inactive surface meristoderm of short cells.

Reproduction: Thalli monoecious. Conceptacles (Fig. 156B) densely scattered over surface of terminal branches (Fig. 156A), sparse in older parts, bisexual, with a broad basal tuft of phaeophycean hairs on a short columella; oogonia sessile, ovoid, 97–175 µm long and 40–110 µm in diameter; antheridia sessile or on branched paraphyses, elongate-ovoid, 24–42 µm long and 10–18 µm in diameter.

Type from Vivonne Bay, Kangaroo I., S. Aust., in large eulittoral pool on S. side of Ellen Point ( Womersley, 2.i.1949); holotype in ADU, A10576.

Selected specimens: St Francis I., Isles of St Francis, S. Aust., 2 m deep (Shepherd, 9.i.1971; ADU, A38121). Point Drummond, S. Aust., upper sublittoral pools (Womersley, 11.i.1951; ADU, A13735). Point 4 km N. of Cape Carnot, S. Aust., upper sublittoral pools (Womersley, 9.i.1987; ADU, A57375). Wedge I., S. Aust., sublittoral fringe (Baldock, 29.xii.1963; ADU, A27262). Vivonne Bay, Kangaroo I., S. Aust., in large eulittoral pool (Womersley, 1.i.1946; ADU, A3311).

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

Distribution: From the Isles of St Francis to Vivonne Bay, Kangaroo I., S. Aust.

Taxonomic notes: M. harveyanum appears to be restricted to the western coasts of South Australia, where it occurs at and just below low tide level (to 8 m deep) in strong water movement. It is characterised by the lacerate holdfast, regularly pinnate fronds with serrate pinnae, and its dimensions.


NIZAMUDDIN, M. & WOMERSLEY, H.B.S. (1967) The morphology and taxonomy of Myriodesma (Fucales). Nova Hedwigia 12, 373–383, Plates 69–73.

NIZAMUDDIN, M. (1962d). Structure and development of Myriodesma (Fucales). Bot. Gaz. 124, 68–74.

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

Illustrations in Womersley Part II, 1997: FIGS 153A, 156A,B.

Figure 153 image

Figure 153   enlarge

Fig. 153. A. Myriodesma harveyanum (ADU, A10576, holotype). B. Myriodesma tuberosum (ADU, A25427).

Figure 156 image

Figure 156   enlarge

Fig. 156. A,B. Myriodesma harveyanum (A, ADU, A57375; B, ADU, A3311). A. Upper branches with conceptacles. B. Transverse section of thallus with bisexual conceptacles each with a central columella bearing phaeophycean hairs. C. Myriodesma tuberosum (ADU, A51679). Upper branches with conceptacles. D,E. Myriodesma quercifolium (D, ADU, A33718; E, ADU, A13435). D. Mid and apical parts of a branch. E. Transverse section of thallus with a bisexual conceptacle and central group of phaeophycean hairs. F. Myriodesma calophyllum. Mid and apical parts of a branch with conceptacles.

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