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Dasya hapalathrix Harvey 1859a: pl. 88; 1859b: 302; 1863, synop.: xxiii.

Phylum Rhodophyta – Order Ceramiales – Family Dasyaceae

Selected citations: J. Agardh 1863: 1211; 1890a: 96, pl. 3 fig 2. De Toni 1903: 1191; 1924: 441. De Toni & Forti 1923: 50. Kützing 1864: 23, pl. 63d–e. Lucas 1912: 157; 1929a: 23; 1929b: 52. Lucas & Perrin 1947: 310, fig. 148. Reinbold 1898: 50? Sonder 1881: 36. Wilson 1892: 165.

Thallus (Fig. 208A, B) medium red-brown, 20 cm –1 (–2) m high, with strongly developed main axes 2–3 mm in diameter and long lateral branches radially developed and bearing third order branches 4–8 cm long, ultimate branches 5–20 mm long and 150–300 µm in axial diameter, with delicate pseudolateral tufts, most branches denuded below. Holdfast probably discoid, 1–3 mm across; epilithic. Structure. Apices sympodial, developing 5 pericentral cells with dense cortication obscuring the pericentral cells close to apices. Pseudolaterals (Fig. 208C, E) one per segment, 1–2 mm long, with 2–4 basal subdichotomies one cell apart and unbranched ends 0.5–1.5 mm and many cells long; lower cells 15–25 (–30) µm in diameter and L/D 1.5–2.5 (–4), upper cells 15–30 µm in diameter and L/D 3–8, tapering at the meristematic apex. Cortication by rhizoidal filaments separating the pericental cells from themselves and the axial filaments but pericentral and large cells visible in most transverse sections. Rhodoplasts discoid to chained or ribbon like.

Reproduction: Gametophytes dioecious. Procarps not observed. Carposporophytes (Fig. 208D) much branched, with a basal fusion cell and terminal clavate carposporangia 18–30 µm in diameter. Cystocarps urceolate, 700–1000 µm in diameter, with a slight neck; pericarp with erect filaments cutting off 3 outer pericentral cells which develop slight outer cortication by elongate cells. Spermatangial branches (Fig. 208E) developed as lower branches of pseudolaterals, cylindrical, 200–700 µm long and 40–65 µm in diameter, with monosiphonous pedicels and short apical filaments, occassionally branched.

Tetrasporangial stichidia (Fig. 208F) on lower cells of pseudolaterals, lanceoid, 150–350 µm long and 45–90 µm in diameter, with a monosiphonous pedicel and each segment with 5 (or 4) pericentral cells and tetrasporangia, with obloid and palisade like cover cells; tetrasporangia 25–55 µm in diameter.

Lectotype from Point Rapid, Tamar Est., Tas. (Harvey, Alg. Aust. Exsicc. 2011); in Herb. Harvey, TCD. Isolectotypes in MEL, 1006638 and AD, A18293.

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

Distribution: Recorded by Harvey (1959a, p1. 85) also from Georgetown, Tas., and Port Phillip Heads, Victoria.

Probably also from Tiparra Reef, S. Aust., 10–12 m deep (Shepherd, 16.iii.1985; AD, A56444).

Taxonomic notes: D. hapalathrix is characterised by the dense cortication to close to the apices, and the form and dimensions of the pseudolateral filaments. The species is based on plants from Point Rapid in the Tamar Estuary (now Barretts Point, at the Batman Bridge), where strong currents flow through a narrow channel. Apart from nearby Georgetown, Harvey also recorded the species from Port Phillip Heads, Victoria. The fronds were stated to be "3–6 feet long". It appears that D. hapalathrix has not been collected in the Tamar Estuary since Harvey, and is now unlikely to occur there due to shipping disturbance and pollution.

The Tiparra Reef, S. Aust., specimens are similar to the type in vegetative features, but the stichidia have consistently 4 tetrasporangia per whorl rather than 5, as in the type; measurements of reproductive structures are based largely on the Tiparra collection. It is highly desirable that D. hapalathrix should be re-collected near the type locality, with liquid-preserved material for detailed investigation.

References to D. hapalathrix from other localities (e.g. Reinbold from Lacepede Bay, S. Aust.) need verification.


AGARDH, J.G. (1863). Species Genera et Ordines Algarum. Vol. 2, Part 3, pp. 787–1291. (Gleerup: Lund.)

AGARDH, J.G. (1890a). Till algernes systematik. Acta Univ. lund. 26(3), 1–125, Plates 1–3.

DE TONI, G.B. & FORTI, A. (1923). Alghe di Australia, Tasmania e Nouva Zelanda. Mein. R. Inst. Veneto Sci., Lett. Arti 29, 1–183, Plates 1–10.

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

DE TONI, G.B. (1924). Sylloge Algarum omnium hucusque Cognitarum. Vol. 6. Florideae. (Padua.)

HARVEY, W.H. (1859a). Phycologia Australica. Vol. 2, Plates 61–120. (Reeve: London.)

HARVEY, W.H. (1859b). Algae. In Hooker, J.D., The Botany of the Antarctic Voyage. III. Flora Tasmaniae. Vol. II, pp. 282–343, Plates 185–196. (Reeve: London.)

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

KÜTZING, F.T. (1864). Tabulae Phycologicae. Vol. 14. (Nordhausen.)

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

LUCAS, A.H.S. (1912). Supplementary list of the marine algae of Australia. Proc. Linn. Soc. N.S.W. 37, 157–171.

LUCAS, A.H.S. (1929a). The marine algae of Tasmania. Pap. Proc. R. Soc. Tasm. 1928, 6–27.

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

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

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 IIIC complete list of references.

Author: M.J. Parsons and H.B.S. Womersley

Publication: Womersley, H.B.S. (24 December, 1998)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIC. Ceramiales – Ceramiaceae, Dasyaceae
©State Herbarium of South Australia, Government of South Australia

Illustration in Womersley Part IIIA, 1998: FIG. 208.

Figure 208 image

Figure 208   enlarge

Fig. 208. Dasya hapalathrix (B, isolectotype in AD, A18293; A, C–F, AD, A56444). A. Habit of isotype. B. Habit of Barker Rocks plant. C. Pseudolaterals and young cystocarp. D. Cystocarp with a mature carposporophyte. E. Spermatangial branches. F. Stichidia on pseudolateral filaments.

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