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Rhodymenia leptophylla J. Agardh 1878: 20.

Phylum Rhodophyta – Class Florideophyceae – Order Rhodymeniales – Family Rhodymeniaceae

Selected citations: Adams 1994: 231, pl. 83 lower left. Chapman & Dromgoole 1970: 134, pl. 44 lower. Dawson 1941: 143. De Toni 1900b: 519. Kylin 1931: 20, pl. 6 fig. 15. Lucas & Perrin 1947: 201. May 1965: 408. Millar 1990: 368, fig. 27C. Millar & Kraft 1993: 33. Tisdall 1898: 506. Wilson 1892: 178.

Thallus (Fig. 25A, B) medium to dark red-brown, fading to grey-red, 4–10 (–30) cm high, with numerous clumped fronds from slender entangled stolons, fronds flat, complanately branched, simple to furcately or palmately branched above with long stipes, branches 2–5 mm broad, usually broadest above, with no or few marginal proliferations, apices rounded when young, tapering in branched apices and often extending as long, subterete, prolongations 10–60 mm long; thallus 300–500 (–800) µm thick; stolons and stipes slender, terete, 5–20 (–60) mm long and 300–1000 µm in diameter, grading upwards to the flat fronds. Holdfasts small digitate pads on the stolons; epilithic. Structure multiaxial, developing a cortex (Fig. 25C) 2–3 cells broad, outer cells ovoid and 2–4 µm in diameter, grading to the medulla 4–8 cells broad, cells rather laxly arranged, ovoid, 30–100 µm in diameter; stipe medulla 300–500 µm and 12–16 cells broad. Rhodoplasts discoid.

Reproduction: Gametangial thalli probably dioecious. Carpogonial and auxiliary cell branches not observed. Carposporophytes (Fig. 25D) 250–500 µm across, with branched basal fusion cells bearing a dense mass of ovoid carposporangia 10–15 µm in diameter. Basal nutritive tissue slight, erect filaments absent. Cystocarps (Fig. 25E) on the blade surfaces, often clustered, sessile, not or slightly basally constricted, slightly conical or beaked, 600–850 µm across, pericarp 100–150 (–300) µm and 8–12 (–25) cells thick (thicker around ostiole), inner cells irregularly placed and the outer cells in anticlinal rows of 3–5, ostiole usually depressed. Spermatangia not observed.

Tetrasporangia (Fig. 25F) in sori near branchlet ends, probably intercalary, the cortex slightly thickened with elongate outer cells and some additional small outer cells; tetrasporangia ovoid to elongate, 20–30 (–40) µm long and 10–15 µm in diameter, decussately divided.

Type from the Bay of Islands, New Zealand; lectotype (Kylin 1931, p. 20, fig. 15) in Herb. Agardh, LD.

Selected specimens: Oedipus Point, West I., S. Aust., 16 m deep (Shepherd, Dec. 1966; AD, A31148). Robe, S. Aust., in shaded pools near jetty (Womersley, 30.x.1993; AD, A63258). Cape Lannes, S. Aust., upper sublittoral pool edges (Womersley, 31.x.1993; AD, A63255). Port MacDonnell, S. Aust., drift (Womersley, Lxi.1994, AD, A63857 -"Marine Algae of southern Australia" No. 384). St Leonards, Port Phillip, Vic., 1–3 m deep (Womersley, 9.viii.1959; AD, A23103). Crawfish Rock, Westernport Bay, Vic., 4 m deep (Watson, 29.v.1974; AD, A45402). Georgetown, Tas., upper sublittoral (Womersley, 29.i.1949; AD, A10287). Cloudy Lagoon, SE Tas., 1–3 m deep (Edgar, 12.ii.1995; AD, A64238).

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

Distribution: New Zealand; N.S.W.; Qld.

In southern Australia, from West I., S. Aust., to Westernport Bay, Vic., and around Tasmania.

Taxonomic notes: R. leptophylla is characterised by its habit, with long slender stipes and stolons. Some of the Australian plants agree well with those from New Zealand, but there is considerable variation in size and degree of branching in southern Australian populations, though all have slender stipes and basal stolons. At Port MacDonnell, large entangled clumps up to 50 cm across occur. Millar (1990, p. 369) discussed New Zealand synonyms of this species.

Weber-van Bosse (1928, p. 461) described a f. minima of R. leptophylla from Indonesia; it seems doubtful if this is related to the southern Australasian taxon.


ADAMS, N.M. (1994). Seaweeds of New Zealand. (Cant. Univ. Press: Christchurch.)

AGARDH, J.G. (1878). De Algis Novae Zelandiae marinis. Acta Univ. lund. 14, 1–32.

CHAPMAN, V.J. & DROMGOOLE, F.I. (1970). The marine algae of New Zealand, Part III: Rhodophyceae. Issue 2: Florideophycidae: Rhodyméniales, pp. 115–154, Plates 39–50. (Cramer: Germany.)

DAWSON, E.Y. (1941). A review of the genus Rhodymenia with descriptions of new species. Allan Hancock Pacif. Exped. 3(7), 115–181.

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.

MILLAR, A.J.K. & KRAFT, G.T. (1993). Catalogue of Marine and Freshwater Red Algae (Rhodophyta) of New South Wales, including Lord Howe Island, South-western Pacific. Aust. Syst. Bot. 6, 1–90.

MILLAR, A.J.K. (1990). Marine Red Algae of the Coffs Harbour Region, northern New South Wales. Aust. Syst. Bot. 3, 293–593.

TISDALL, H.T. (1898). The algae of Victoria. Rep. 7th Meet. Aust. Ass. Adv. Sci., Sydney, 1898, pp. 493–516.

WEBER-VAN BOSSE, A. (1928). Liste des Algues du Siboga. IV. Rhodophyceae. Part 3. Gigartinales and Rhodyméniales. Siboga-Expeditae, Monogr. LIXd, pp. 393–533, Plates 11–16.

WILSON, J.B. (1892). Catalogue of algae collected at or near Port Phillip Heads and Western Port. Proc. R. Soc. Vict. 4, 157–190.

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.

Illustrations in Womersley Part IIIA, 1996: PLATE 1 fig. 4; FIG. 25.

Plate 1 image

Plate 1   enlarge

figure 1. Gracilaria ramulosa (AD A63002). Photograph - H.B.S. Womersley.
figure 2. Cordylecladia furcellata (AD, A64395). Photograph - G. Edgar.
figure 3. Coelarthrum opuntia (AD, A64473). Photograph - K.L. Gowlett-Holmes.
figure 4. Rhodymenia leptophylla (AD, A64238). Photograph - G. Edgar.

Figure 25 image

Figure 25   enlarge

Fig. 25. Rhodymenia leptophylla (A, D, AD, A63258; B, C, E, F, AD, A23103). A, B. Habit. C. Transverse section of branch. D. Section of carposporophyte. E. Section of cystocarp. F. Transverse section through tetrasporangial sorus.

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