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Electronic Flora of South Australia Species Fact Sheet

Melanthalia abscissa (Turner) Hooker & Harvey 1845: 548; 1847: 406.

Phylum Rhodophyta – Class Florideophyceae – Order Gracilariales – Family Gracilariaceae

Selected citations: Adams 1994: 180, pl. 56 lower. J. Agardh 1852: 613; 1876: 404. De Toni 1900b: 421. Kylin 1932: 59, fig. 17D. Papenfuss 1935: 1, figs 1–10.


Fucus abscissus Turner 1819: 66, pl. 223.

Sphaerococcus abscissus (Turner) C. Agardh 1822: 252.

Chondrococcus abscissus (Turner) Kützing 1849: 752; 1867: 29, pl. 96c, d.

Melanthalia jaubertiana Montagne 1843: 299, pl. 13. J. Agardh 1852: 613. Kützing 1849: 784; 1869: 16, pl. 43b, c(?). Sonder 1853: 689.

Melanthalia obtusata var. intermedia Harvey 1858: pl. 25 fig. 2.

Melanthalia intermedia (Harvey) J. Agardh 1879: 127, pl. 23 figs 10, 11. Tisdall 1898: 508.

Melanthalia billardieri var. angustata Sonder 1855: 522.

Melanthalia muelleri Kützing 1869: 16, pl. 43a.

Melanthalia obtusata var. abscissa (Turner) Chapman 1979: 309, fig. 84, pls 118, 119. Fredericq & Hommersand 1990c: 4, figs 1–22.

Melanthalia obtusata var. jaubertiana (Montagne) Chapman 1979: 311, pl. 120.

Thallus (Fig. 10A) dark red-brown, 10–40 cm high, subdichotomously and essentially complanately branched from the margins, mostly at intervals of 0.5–2 cm, branches compressed, 0.7–1.3 mm broad, linear, ovate to elliptic in transverse section, branch apices with a distinct thickened cap and 0.7–1 mm broad just below apex. Holdfast discoid, 3–25 mm across, bearing few to numerous terete stipes; epilithic. Structure multiaxial (Fig. 10B), with sudden transition from densely protoplasmic cap cells to clearer and larger medullary cells, pseudoparenchymatous throughout with small outer cortical cells 3–4 µm in diameter and L/D 1–1.5 (–2), in anticlinal rows, the apical cells dividing obliquely longitudinally and then transversely, secondary pit-connections and cell globules frequent; medullary cells 10–25 (–40) µm in diameter, walls 2–3 µm thick. Rhodoplasts discoid to lobed.

Reproduction: Female plants with 2-celled carpogonial branches borne near the branch margins on mid cortical supporting cells with closely adjacent cortical branches. Carposporophytes (Fig. IOC) with a dense gonimoblast reticulum involving a small basal fusion cell and other fusion centres, and fusions between gonimoblast and gametophyte cells, and with a dense tuft of erect gonimoblast filaments terminating in straight chains of numerous ovoid to subspherical carposporangia (Fig. 10D) 8–12 µm in diameter, maturing apically. Cystocarps marginal or submarginal, hemispherical, 1–1.5 mm across; pericarp massive, with inner tangentially elongate cells and outer anticlinal rows 6–8 µm in diameter, with a prominent ostiole. Spermatangia not observed.

Tetrasporangial nemathecia (Fig. 10E) shallow, inconspicuous, on upper branches; tetrasporangia pit-connected to basal cells within the dense layer of 2–3-celled paraphyses 30–45 µm long and 3–5 µm in diameter, sporangia ovoid, 20–25 µm long and 7–10 µm in diameter, cruciately divided.

Type from New Zealand (Banks); lectotype (?) in BM.

Selected specimens: 7 km SE of Wedge I., S. Aust., 22–35 m deep (Baldock, 4.i.1964; AD, A27188). Althorpe I., S. Aust., 9–13 m deep N side (Baldock, 4.i.1964; AD, A27217). Toad Head, West I., S. Aust., 6–9 m deep (Shepherd, 15.i.1966; AD, A30170). Port Elliot, S. Aust., drift (Womersley, 24.vii.1949; AD, A11141). Robe, S. Aust., drift (Womersley, 29.viii.1949; AD, A11011). Lawrence Rock, Portland, Vic., 24–30 m deep 1.6 km W of Rock (Owen, 2.ix.1971; AD, A39670). Warrnambool, Vic., drift (Womersley, 13.iv.1959; AD, A22918). Little Squally Cove, Deal I., Bass Strait, 5 m deep (Shepherd & R. Lewis, 3.v.1974; AD, A45202). Port Arthur, Tas. (Perrin 506 & Lucas; BM).

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

Distribution: New Zealand.

In southern Australia, from Wedge I., S. Aust., to Wilsons Prom., Vic. (Sonder) and around Tasmania.

Taxonomic notes: M. abscissa has usually been placed as a variety of M. obtusata but they appear to be quite distinct in branch width, although very similar structurally and reproductively. The type of M. jaubertiana was from SE Tasmania, Montagne (1843, p. 299) stating "Hab. cum priori" which was "littora Van-Dieman" for M. billardieri. In transferring F. abscissus to Melanthalia, Hooker & Harvey (1845, p. 549) commented on the similarity between this species and M. jaubertiana Montagne. The lectotype of var. intermedia of M. obtusata is Alg. Aust. Exsicc. 319D from Port Fairy, Vic., in Herb. Harvey, TCD. Harvey (1858, pl. 25) commented that var. intermedia was "frequently found growing from the same base as the normal form" (i.e. M. obtusata), but this has never been observed by the present author. The holotype of M. muelleri Kützing is from Belfast, Vic. (Mueller) and is in L, 941, 149 ... 65.


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

AGARDH, C.A. (1822). Species Algarum. Vol. 1, Part 2, pp. 169–398. (Berling: Lund.)

AGARDH, J.G. (1852). Species Genera et Ordines Algarum. Vol. 2, Part 2, pp. 337–720. (Gleerup: Lund.)

AGARDH, J.G. (1876). Species Genera et Ordines Algarum. Vol. 3, Part 1 — Epicrisis systematis Floridearum, pp. i-vii, 1–724. (Weigel: Leipzig.)

AGARDH, J.G. (1879). Florideernes morphologi. K. Svenska Vetensk. Akad. Handl. 15(6), 1–199, Plates 1–33.

CHAPMAN, V.J. (1979). The marine algae of New Zealand. Part III: Rhodophyceae. Issue 4: Gigartinales, pp. 279–509. (Cramer: Germany.)

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

FREDERICQ, S. & HOMMERSAND, M.H. (1990c). Taxonomy of Melanthalia obtusata var. abscissa and its placement in the Gracilariales (Rhodophyta). Crypt. Bot. 2, 4–11.

HARVEY, W.H. (1858). Phycologia Australica. Vol. 1, Plates 1–60. (Reeve: London.)

HOOKER, J.D. & HARVEY, W.H. (1845). Algae Novae Zelandiae. Lond. J. Bot. 4, 521–551.

HOOKER, J.D. & HARVEY, W.H. (1847). Algae Tasmanicae. Lond. J. Bot. 6, 397–417.

KÜTZING, F.T. (1849). Species Algarum. (Leipzig.)

KÜTZING, F.T. (1867). Tabulae Phycologicae. Vol. 17. (Nordhausen.)

KÜTZING, F.T. (1869). Tabulae Phycologicae. Vol. 19. (Nordhausen.)

KYLIN, H. (1932). Die Florideenordnung Gigartinales. Lunds Univ. Årsskr. N.F. Avd. 2, 28 (8), 1–88, Plates 1–28.

MONTAGNE, C. (1843). Quatrième centurie de plantes cellulaires exotiques nouvelles. Ann. Sci. Nat. Sér. 2, Bot. 20, 294–306.

PAPENFUSS, G.F. (1935). The development of the gonimoblast in Melanthalia abscissa. K. Fysiogr. Sällsk. Lund. Förh. 5, 1–10.

SONDER, O.W. (1853). Plantae Muellerianae. Algae. Linnaea 25, 657–709.

SONDER, O.W. (1855). Algae annis 1852 et 1853 collectae. Linnaea 26, 506–528.

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

TURNER, D. (1819). Fuci sive Plantarum Fucorum Generi a Botanicis Ascriptarum Icones Descriptiones et Historia. Vol. 4, pp. 1–153, Plates 197–258. (London.)

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. 10.

Figure 10 image

Figure 10   enlarge

Fig. 10. Melanthalia abscissa (A–D, AD, A 1 1 141; E, AD, A30170). A. Habit. B. Longitudinal section through apical cap. C. Longitudinal section through a cystocarp. D. Section of cystocarp with chains of carposporangia. E. Transverse section of thallus with a tetrasporangial sorus.

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