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Codium silvae Womersley sp. nov.

Phylum Chlorophyta – Order Codiales – Family Codiaceae

Thallus (Fig. 77D) medium green. erect, to 30 cm high, irregularly dichotomously and laterally branched at intervals of one to several cm, branches terete, tapering gradually from 6–8 mm in diameter near the base to 3–5 mm in diameter near the branch apices. Utricles (Fig. 78D) arising singly from medullary filaments, elongate clavate to subterete and often of greatest diameter shortly below the apex, 125–250 µm in diameter when mature and (750–) 850–1150 µm long; utricle wall thin near the base, thickening towards the apex and forming a finely lamellate, often galeate, cap 25–40 µm thick; internal spinous trabeculae (Fig. 78D,E) formed profusely from the galeate cap, occurring with less frequency and smaller size downwards over the upper quarter to one third of the utricle; trabeculae 10–30 µm long, basally 5–20 µm thick, tapering to a point, simple or rarely with a branch, often appearing to have an internal cavity which extends into the utricle wall; hairs probably rare, only a few possible hair-scars observed about one quarter of the length of the utricle from the apex. Medullary filaments 25–50 µm in diameter, with a prominent plug adjacent to the utricle base. Garnetangia borne one third to a half the utricle length from the apex, terete to lanceolate, one or two per utricle. 180–300 µm long by 50–70 µm in diameter (only discharged gametangia seen).

Type : Eucla, W. Aust. ( Womersley, 5.x.1979). Holotype: ADU, A50695. Isotypes distributed to MEL, PERTH and UC. Distribution: Only known from the type collection of a single plant.

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

Taxonomic notes: Named after Dr Paul C. Silva, who has contributed most significantly to our knowledge of Codiutn.

C. silvae is similar in dimensions to C. galeatum but differs in having irregularly placed, often short, lateral branches. The utricles are also similar in dimensions and have a pronounced galeate cap, but differ strikingly in the internal, spinous trabeculae which occur for some distance down the wall of the utricle. These spines appear to be trabeculae in the sense of Silva (1951, p. 93) and show internal structure corresponding to the "conspicuous axial filament" referred to by Silva. However, this structure in C. silvae, which is very similar to that illustrated by Silva (1951, figs 17–19) in Codium globosum from Queensland, appears to be a cavity within the trabeculae, and which often extends into the utricle wall. Setchell (1940, p. 447, figs 3–5) considered the trabeculae had a "distinct core (or tube)?" when describing C. cranwelliae (from New Zealand), but Silva considered them to be solid structures.

C. siivae appears to be the only erect, dichotomous species of Codium showing trabeculae, the other such species being prostrate or globose taxa. Lucas (1935, p. 206) however mentioned trabeculae in a Lord Howe Island plant he (probably incorrectly) referred to C. cuneatum Setchell & Gardner.


LUCAS, A.H.S. (1935). The marine algae of Lord Howe Island. Proc. Linn. Soc. N.S. W. 60, 194–232, Plates 5–9.

SETCHELL, W.A. (1940). Some trabeculate Codiums (including two new species). Proc. nat! Acad. Sci. 26, 443–448.

SILVA, P.C. (1951). The genus Codium in California with observations on the structure of the walls of the utricles. Univ. Calif. Publ. Bot. 25, 79–114.

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

Illustrations in Womersley Part I, 1984: FIGS 77D, 78D,E.

Figure 77 image

Figure 77   enlarge

Fig. 77. A. Codium mamillosum (ADU, A43513). B. Codium pomoides (ADU, A46816). C. Codium laminarioides (ADU, A50719). D. Codium silvae (ADU, A50695, type). E. Codium galeatum (ADU, A46820). F. Codium duthieae (ADU, A37513).

Figure 78 image

Figure 78   enlarge

Fig. 78. Utricle clusters with gametangia. A. Codium mamillosum (Royce 1200, in PERTH, UC). B. Codium pomoides (Cribb 75.16 in UC). C. Codium laminarioides (Cribb 61.42 in UC). D. Codium silvae (ADU, A50695, type). E. Codium silvae, apex of utricle. F. Codium galeatum (lectotype left and Royce 1196 right). G. Codium duthieae (ADU, A13624). (After Silva & Womersley 1956.)

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