Electronic Flora of South Australia Species Fact Sheet

Dictyomenia angusta J. Agardh 1897: 60.

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Pterosiphonieae

Selected citations: De Toni 1903: 987. Lucas 1909: 42; 1929b: 51. Lucas & Perrin 1947: 282. May 1965: 395. Reinbold 1898: 48. Silva et al. 1996: 488.

Reproduction: Only tetrasporangial branch clusters seen, situated on the surface over lateral veins of determinate laterals, much branched; tetrasporangia immature.

Type from "occidentales, turn australes Novae Hollandiae"; lectotype from Port Elliot, S. Aust. (Hussey); in Herb. Agardh, LD, 42315.

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

Distribution: Port Elliot, S. Aust., and Walkerville, Victoria. J. Agardh placed similar specimens from Geographe Bay, W. Aust., under this species.

Taxonomic notes: Thallus (Fig. 151H) dark brown-red, erect, 10–25 cm high, complanately and irregularly branched with indeterminate branches 1–2 mm broad and separated by 3 to many determinate laterals on each side. Determinate laterals 2–3 (–5) mm long, slender, usually with 2–3 apical branches, 2–5 mm apart on each side of indeterminate branches, denuded near the thallus base. Holdfast probably fibrous (inadequately seen). Structure. Apical structure not observed. Axial cells moderately conspicuous, branching to the determinate laterals every 3–4 cells. Indeterminate branches with 6 pericentral cells, corticated from near the apices; indeterminate laterals corticated. Trichoblasts not observed.

D. angusta is known from only few herbarium specimens and needs detailed study from fresh material. While seemingly distinct in habit, it is closest to D. tridens, differing in much sparser branching and longer and more widely spaced determinate laterals. It may, however, be an unusual form of D. tridens.

References:

AGARDH, J.G. (1897). Analecta Algologica. Cont. IV. Acta Univ. lund. 33, 1–106, Plates 1, 2.

DE TONI, G.B. (1903). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 3. pp. 775–1521 + 1523–1525. (Padua.)

LUCAS, A.H.S. & PERRIN, F. (1947). The Seaweeds of South Australia. Part 2. The Red Seaweeds. (Govt Printer: Adelaide.)

LUCAS, A.H.S. (1909). Revised list of the Fucoideae and Florideae of Australia. Proc. Linn. Soc. N.S.W. 34, 9–60.

LUCAS, A.H.S. (1929b). A census of the marine algae of South Australia. Trans. R. Soc. S. Aust. 53, 45–53.

MAY, V. (1965). A census and key to the species of Rhodophyceae (red algae) recorded from Australia. Contr. N.S. W. Natl Herb. 3, 349–429.

REINBOLD, T. (1898). Die Algen der Lacepede und Guichen Bay (Süd Australien) und deren näherer Umgebung, gesammelt von Dr. A. Engelhart-Kingston. II. Nuova Notarisia 9, 33–54.

SILVA, P.C., BASSON, P.W. & MOE, R.L. (1996). Catalogue of the Benthic Marine Algae of the Indian Ocean. (Univ. California Press: Berkeley.)

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

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustration in Womersley Part IIIA, 2003: FIG. 151H.

Figure 151   enlarge

Fig. 151. A–G. Dictyomenia sonderi (A, AD, A47866; B, AD, A33211; C, F, AD, A19572; D, E, G, AD, A64431). A. Habit. B. Indeterminate branch with marginal determinate laterals. C. Apex of indeterminate branch with determinate laterals. D. Transverse section of young branch with axial and 6 pericentral cells. E. Transverse section of older branch with thickened midrib. F. Cystocarps. G. Branches with tetrasporangia. H. Dictyomenia angusta (type, LD, 42315). Habit.

Email Contact: State Herbarium of South Australia