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Hymenocladia filiformis J. Agardh 1892: 83.

Phylum Rhodophyta – Class Florideophyceae – Order Rhodymeniales – Family Rhodymeniaceae

Selected citations: De Toni 1900b: 501. Kylin 1931: 24, pl. 11 fig. 26. Lucas & Perrin 1947: 196. May 1965: 387. Sparling 1957: 367.


Hymenocladia subulosa J. Agardh 1896: 91. De Toni 1900b: 501. Kylin 1931: 24, pl. 11 fig. 25. May 1965: 387. Sparling 1957: 367.

Thallus (Fig. 46A) 4–14 cm high, subdichotomously to laterally branched largely complanately, branches slightly compressed, 0.5–1 mm broad below, tapering slightly to 0.2–0.5 mm broad above, apices rounded. Holdfast discoid; epiphytic on Amphibolis. Structure multiaxial, with a cortex 2–3 (–4) cells broad, outer cells ovoid and 2–3 µm in diameter, and a medulla (3–) 5–8 cells across (Fig. 46B), inner cells ovoid and 80–150 (–200) µm in diameter, with small-celled filaments lying between the larger cells in older branches. Rhodoplasts discoid, ribbon like in inner cells.

Reproduction: Early reproductive structures unknown. Carposporophytes (Fig. 46C, D) with a basal fusion cell and gonimoblast cells all becoming ovoid carposporangia 45–100 µm in diameter. Basal nutritive tissue (Fig. 46D) well developed, erect filaments disintegrating but cell walls of lower cells remaining. Cystocarps hemispherical, not or slightly basally constricted, 700–1200 µm in diameter, pericarp 100–200 µm and 8–12 cells thick, ostiolate. Spermatangia unknown.

Tetrasporangia (Fig. 46E) scattered in branches, transformed from outer medullary cells, 80–140 µm in diameter, tetrahedrally to cruciately divided.

Type from Champion Bay, W. Aust. (Spalding); lectotype in Herb. Agardh, LD, 26217.

Selected specimens: Cervantes, W. Aust., drift on Amphibolis (M. & F. Hommersand, 20.ix.1995; AD, A64490). Yanchep, W. Aust., drift on Amphibolis (Kraft 8448 & Herrington, 5.ix.1990; MELU; AD, A64492). Eucla, W. Aust., drift on Amphibolis (Kerry, Sept. 1975; G.K. 5731; MELU; AD, A64491).

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

Distribution: Champion Bay to Eucla, W. Aust.

Taxonomic notes: The type specimens are cystocarpic and have the distinctive basal nutritive tissue of Hymenocladia (and other Rhodymeniaceae). Tetrasporangial specimens also agree with Hymenocladia. The type of H. subulosa from Eucla, W. Aust. (Ryan); lectotype (Kylin 1931, fig. 25) in Herb. Agardh, LD, 26211, and the Eucla specimen cited above, appear identical with H. filiformis from the west coast.

As well as the four species from southern Australia, two other little known species occur on the west coast of Western Australia.


AGARDH, J.G. (1892). Analecta Algologica. Acta Univ. lund. 28, 1–182, Plates 1–3.

AGARDH, J.G. (1896). Analecta Algologica. Cont. III. Acta Univ. lund. 32, 1–140, Plate 1.

DE TONI, G.B. (1900b). Sylloge Algarum omnium hucusque Cognitarum. Vol. 4. Florideae. Sect. 2, pp. 387–776. (Padua.)

KYLIN, H. (1931). Die Florideenordnung Rhodyméniales. Lunds Univ. Årsskr. N.F. Avd. 2, 27 (11), 1–48, Plates 1–20.

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

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

SPARLING, S.R. (1957). The structure and reproduction of some members of the Rhodymeniaceae. Univ. Calif Pubis Bot. 29, 319–396.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustration in Womersley Part IIIA, 1996: FIG. 46.

Figure 46 image

Figure 46   enlarge

Fig. 46. Hymenocladia filiformis (A, C, D, AD, A64490; B, E, AD, A64491). A. Habit. B. Transverse section of branch showing small cells between large medullary cells. C. Section of a cystocarp with carposporophyte and basal nutritive tissue. D. Base of carposporophyte with fusion cell, basal nutritive tissue and cell walls of disintegrated erect filaments. E. Transverse section of a branch with two tetrasporangia.

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