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Hypnea ramentacea (C. Agardh) J. Agardh 1876: 561.

Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales – Family Hypneaceae


Chondria ramentacea C. Agardh 1822: 354.

Merrifieldia ramentacea (C. Agardh) J. Agardh 1885: 57. De Toni 1900: 469. Kylin 1932: 47.

Hypnea episcopalis Hooker & Harvey 1847: 406. J. Agardh 1852: 443; 1876: 561. De Toni 1900: 473. Fuhrer et al. 1981: pl. 60. Harvey 1855a: 552; 1858: pl. 23; 1859b: 315; 1863, synop.: xxxvi. Kützing 1849: 760; 1868: 10, pl. 30d-h.

Hypnea rigens Sonder 1853: 684. Harvey 1863, synop.: xxxvi.

Hypnea cystoclonioides Sonder 1855: 519. Harvey 1863, synop.: xxxvi.

Hypnea ceramioides var. uncinata Kützing 1868: 8, pl. 24.

Hypnea valida J. Agardh 1896: 108. De Toni 1900: 473.

Thallus (Fig. 153D) dark red, (6–) 10–25 cm high, often with an entangled base and erect percurrent axes bearing dense, radial, laterals of varying lengths, lower thallus branches often relatively bare, elsewhere with numerous short spinous branchlets especially on central parts of axes and branches, and with many axes, longer branches and lower laterals terminating in thickened hamate ends (Fig. 153D); all branches terete or subterete, axes 0.5–1 (–1.2) mm in diameter below, lesser branches 200–400 µm in diameter, basally not or slightly constricted. Attachment mainly by lower hamate branches, probably with a discoid holdfast when young; usually epiphytic. Structure uniaxial with a protruding apical cell, axial filament recognisable throughout, becoming 25–80 (–100) µm in diameter with cells L/D 4–6, surrounded by a medulla 2–3 cells broad, cells ovoid and 40–100 (–200) iiM in diameter with numerous secondary pit-connections, and a small-celled cortex 1–2 cells broad, outer cells 4–9 µm in diameter and L/D 1–2. Rhodoplasts discoid, several to numerous per cell.

Reproduction: Sexual thalli dioecious. Carpogonial branches and early post-fertilization stages not observed. Carposporophyte (Fig. 153E) with a lax reticulum of elongate cells arising basally and pit-connected to inner pericarp cells, with shorter cells producing clusters of small cells which cut off single, subspherical to ovoid, carposporangia 20–35 µm in diameter. Cystocarps sessile, broad based, conical to globular, (600–) 750–1000 µm in basal diameter, with a pericarp 4–8 cells thick, slightly beaked, ostiolate. Spermatangia (Fig. 153G) borne in sori surrounding lower to mid parts (Fig. 153F) of lateral branchlets or lesser branches, with initials from outer cortical cells producing chains of 3–5 ovoid spermatangia (Fig. 154C) 2–3 µm in diameter.

Tetrasporangia in swollen nemathecia (Fig. 155A) partly or wholly around the lateral branchlets or lesser branches just above their bases, laterally to basally pit-connected to inner cortical cells (Fig. 155B), ovoid, 40–65 µm long and 20–38 µm in diameter, zonately divided successively but rapidly.

Type from "Novae Hollandiae"; holotype in PC ("No. 21"), fragment in Herb. Agardh, LD, 27514.

Selected specimens: Port Denison, W. Aust., on reef (Womersley, 31.viii.1947; AD, A5849). Whitfords Beach, Perth, W. Aust., 6 m deep (Cook, 20.viii.1979; AD, A50567). Rottnest I., W. Aust., drift on Scytothalia (Smith, 15.xi.1945; AD, A2137). Esperance, W. Aust. (Firman, Dec. 1951; AD, A18917). Pearson Is, S. Aust., 20–25 m deep (Shepherd, 8.i.1969; AD, A33859). Waterloo Bay, S. Aust., 4 m deep (Shepherd, 26.ii.1978; AD, A54993). Wanna, S. Aust., drift (Womersley, 19.ii.1959; AD, A22371). Dubious Rock, West I., S. Aust., 10 m deep (Shepherd, 3.i.1966; AD, A30272). Vivonne Bay, Kangaroo I., S. Aust., 1–4 m deep on jetty (Kraft, 6.iv.1972; AD, A42362) and 3–6 m deep on jetty (Kraft, 15.iv.1973; AD, A43719). 400 m off Cape Buffon, S. Aust., 5 m deep (Collings, 25.i.1991; AD, A61233). Glenelg R. mouth, Vic., drift (Beauglehole, 26.i.1952; AD, A21696). Cape Woolamai, Vic., 15–18 m deep (Goldsworthy & Berthold, 16.ii.1990; AD, A60194). Walkerville, Vic., drift (Sinkora A2293, 6.iii.1976; AD, A48439). Rocky Cape, Tas., drift (Gordon, 18.i.1966; AD, A29957). Georgetown, Tas., upper sublittoral (Womersley, 29.i.1949; AD, A10252).

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

Distribution: Port Denison, W. Aust., to Walkerville, Vic., and the N coast of Tasmania.

Taxonomic notes: The type of H. ramentacea (in PC) is a sterile specimen and without hamate branches, but otherwise agrees well with the species commonly known as H. episcopalis. Another specimen named Chondria ramentacea, from "Occid. Nov. Ho11.", in PC, does have some hamate branches. H. ramentacea is a common species on rough-water coasts, epiphytic on a variety of other algae. It is usually readily recognised by its dark red colour and profuse branthing with many hamate ends. The formation of chains of 3–5 spermatangia also appears distinctive.

H. ramentacea is the type species of Merrifieldia J. Agardh, though his descriptions and figures (1885, pp. 55, 56, fig. 5 1, m) probably apply to a different species (the type was sterile). Merrifieldia was placed in synonymy under Hypnea by Kylin (1932, p. 47) but the species was not compared with H. episcopalis. The holotype of H. rigens Sonder, from Holdfast Bay, S. Aust., is in MEL, 698108, also the lectotype of H. cystoclonioides (MEL, 698106, left specimen) from Wilsons Prom., Vic.; both are H. ramentacea.


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. (1885). Till algemes systematik. VII. Florideae. Acta Univ. lund. 21, 1–120, Plate 1.

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

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

FUHRER, B., CHRISTIANSON, I.G., CLAYTON, M.N. & ALLENDER, B.M. (1981). Seaweeds of Australia. (Reed: Sydney.)

HARVEY, W.H. (1855a). Some account of the marine botany of the colony of Western Australia. Trans. R. Ir. Acad. 22, 525–566.

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

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. Flora Tasmaniae. Vol. II, pp. 282–320.

HARVEY, W.H. (1863). Phycologia Australica. Vol. 5, Plates 241–300, synop., pp. i-lxxiii. (Reeve: London.)

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. (1868). Tabulae Phycologicae. Vol. 18. (Nordhausen.)

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

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.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

Illustrations in Womersley Part IIIA, 1994: FIGS 153 D–G, 154C, 155A, B.

Figure 153 image

Figure 153   enlarge

Fig. 153. A–C. Hypnea filiformis (A, AD, A54290; B, AD, A38704; C, AD, A41588). A. Habit. B. Transverse section of older branch. C. Section of cystocarp with clusters of carposporangia. D–G. Hypnea ramentacea (D, AD, A54993; E, AD, A43719; F, G, AD, A42362). D. Habit. E. Section of cystocarp with clusters of carposporangia. F. Laterals with spermatangial sori. G. Longitudinal section of spermatangial branchlet.

Figure 154 image

Figure 154   enlarge

Fig. 154. A, B. Hypnea filiformis (A, AD, A19769; B, AD, A61512). A. Section of cortex with spermatangia. B. Transverse section of cortex with tetrasporangia. C. Hypnea ramentacea (AD, A42362). Section of cortex with spermatangia. D, E. Hypnea charoides (D, AD, A61582; E, AD, A60042). D. Section of cortex with spermatangia. E. Section of cortex with tetrasporangia. F. Hypnea valentiae (AD, A48965). Section of cortex with tetrasporangia. G–I. Catenella nipae (G, AD, A60381; H–I, AD, A26432). G. Habit of a tetrasporangial plant. H. Longitudinal section of apical segment with several carpogonial branches and a fusion cell producing gonimoblast initials. I. Longitudinal section of cortex with tetrasporangia. [H, I after Min-Thein & Womersley 1976.]

Figure 155 image

Figure 155   enlarge

Fig. 155. A, B. Hypnea ramentacea (AD, A43719). A. Branchlets with tetrasporangial nemathecia. B. Longitudinal section of branchlet with tetrasporangia. C–F. Hypnea charoides (D, E, AD, A61582; C, F, AD, A60042). C. Habit. D. Section of a cystocarp with clusters of carposporangia. E. Clusters of small cells of the carposporophyte and single, large, carposporangia. F. Spermatangial branchlets.

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