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Gracilaria flagelliformis (Sonder) Womersley, comb. nov.

Phylum Rhodophyta – Class Florideophyceae – Order Gracilariales – Family Gracilariaceae


Polyides flagelliformis Sonder 1845: 55.

Gigartina flagelliformis (Sonder) Sonder 1848: 176. J. Agardh 1851: 283. De Toni 1897: 227. Kützing 1849: 751; 1869: 7, pl. 18c, d.

Gracilaria harveyana J. Agardh 1885: 59; 1901: 65. De Toni 1900b: 441; 1924: 257. May 1948: 56, pl. 15 fig. 1; 1965: 393. Withell et al. 1994: 291, figs. 9, 10.

Gracilaria paradoxa J. Agardh 1901: 67. De Toni 1924: 257. May 1948: 59.

Thallus (Fig. 6A) dark red-brown, 20–60 cm high, irregularly laterally branched at intervals of 1–6 cm below, upper parts often unbranched for many centimetres, branches terete, 0.5–1 mm in diameter above, usually markedly thicker (2–3.5 mm in diameter) near the base where the cortex is thickened. Holdfast discoid, 2–6 mm across, with one to several stipes; epilithic. Structure appearing multiaxial, pseudoparenchymatous (Fig. 6B, C) throughout, with an even gradation over many cells from small outer cortical cells 4–6 (–8) µm in diameter and L/D (1–) 2–4, arranged in anticlinal rows which extend to many cells long in older basal parts (Fig. 6C), through radially elongate cells (L/D 2–4) of the inner cortex and outer medulla, to the inner medulla of large and small cells intermixed, the larger cells ovoid, 50–120 (–160) µm in diameter, with very numerous secondary pit-connections and walls becoming 10–20 µm thick; medulla (15–) 20–30 cells broad. Rhodoplasts discoid.

Reproduction: Gametangial thalli dioecious. Carpogonial branches not observed. Carposporophytes (Fig. 6D) with a basal mass of gonimoblast cells and probably a small basal fusion cell, and upper gonimoblast filaments producing short chains of ovoid carposporangia (Fig. 6E) maturing terminally, 15–25 µm in diameter, with traversing nutritive filaments (Fig. 6F). Cystocarps ovoid, 1–1.6 mm across, slightly basally constricted; pericarp massive, with anticlinal chains of cells mostly 10–25 µm across with prominent lateral secondary pit-connections, and with an ostiole lined with chains of short cells cut off from pericarp cells; inner pericarp prominent. Spermatangia in deep pits, some becoming compound, 40–150 µm broad and up to 175 µm deep (Withell et al. 1994, p. 292, fig. 9C, D).

Tetrasporangia (Fig. 6G) in surface sori around the branches, in a slightly thickened cortex, basally pit-connected to mid cortical cells, elongate-ovoid, 30–55 (–70) µm long and 12–25 (–40) µm in diameter, cruciately divided.

Type from "Occid. Nov. Holl." (Preiss); holotype in MEL, 652097.

Selected specimens: Lancelin, W. Aust., 14 m deep on "2 mile reef" (AIMS-NCI, Q66C 2733-M, 18.iii.1989; AD, A59736). Yanchep, W. Aust., drift (Kraft 8524, 20.ix.1990; MELU, 40688). Ocean Reef Marina, Perth, W. Aust., 6 m deep (O'Brien & Millar, 9.xii.1980; MELU, 24325). Whitford Beach, Perth, W. Aust., 6 m deep (Cook CS14, 20.viii.1979; AD, A50580). Leighton Estuary, Mandurah, W. Aust., drift (Wollaston, 4.ii.1957; AD, A22113). Capel Beach, W. Aust., on rocks below low water (Royce 361, 17.ix.1949; AD, A14146). West Beach, Bunbury, W. Aust., upper sublittoral (Wollaston, 6.ii.1957; AD, A23971). Geographe Bay, W. Aust. (Feb. 1880; MEL, 501401–501403).

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

Taxonomic notes: Distribution: Geraldton to Geographe Bay, W. Aust. (doubtfully further south).

The above description is based on dried herbarium specimens in AD, which indicate that G. flagelliformis is distinctive in form, in having thick lower branches with an expanding cortex and in the relatively dense sori of tetrasporangia. Further studies on good liquid preserved material are needed.

The type of G. flagelliformis in MEL is accompanied by Sonder's drawings of sections with tetrasporangia, showing the thick cortex; Kützing's pl. 18 fig. c is a near mirror image of the left of three pieces. Both G. harveyana J. Agardh and G. paradoxa J. Agardh appear to be based on Harvey's ms name of Chondria paradoxa given to Clifton specimens from Swan R., W. Aust. Apparently J. Agardh first gave it the name G. harveyana and later reverted to Harvey's name paradoxa. The same type (LD, 29255) applies to both names in Herb. Agardh.

Polyides flagelliformis Sonder 1845 is the earliest valid name for this species, which is here transferred to Gracilaria. However, there are two previous but invalid mentions of the name Gracilaria flagelliformis Suhr mscr in J. Agardh (1852, p. 588) as a synonym of G. tuberculosa, and of G. flagelliformis J. Agardh (nomen) in Mueller (1874, p. 209), a species which was validly published as G. flagellifera J. Agardh (1876, p. 412) (Dr Paul Silva, pers. comm.).

G. flagelliformis may not occur south of Cape Naturaliste. The Fowler Bay, S. Aust. (Richards) record (May 1948, p. 58), based on specimens in MEL (629941, 629942) are more likely robust G. ramulosa, and the records of Reinbold (1848, p. 46) and Lucas (1929b, p. 49) are doubtful. Nelson (1987, p. 96) rejects G. harveyana from the New Zealand flora.

Withell et al. (1994, p. 293) prefer to recommend conservation of the name G. harveyana J. Agardh (1885) over the much earlier (P.) flagelliformis Sonder (1845), as under Art. 14 of the Tokyo code of the I.C.B.N. The Article commences "In order to avoid disadvantageous changes in nomenclature ..." and "aims at retention of those names which best serve stability of nomenclature". There are five references to flagelliformis (mainly as Gigartina) after the original description, those of J. Agardh (1852) and Kützing (1869, with illustrations) involving further taxonomic study in that they elaborate on Sonder's original description. There are six references to Australian G. harveyana following the original one of J. Agardh (1885), but this name is scarcely "well documented" as Withell et al. claim. Conservation of species' names may be justified for very well-known species (such as Ceramium rubrum) but conservation of names of little known Australian species, rather than following the rule of priority that has applied in the past and is still basic to the ICBN, will surely lead to a chaotic situation. Adoption of the name flagelliformis for this Gracilaria is in accord with the ICBN rules for a little-known species, and conservation of the epithet harveyana is here rejected.


AGARDH, J.G. (1851). Species Genera et Ordines Algarum. Vol. 2, Part 1, I-XII, 1–336 + index. (Gleerup: 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 algernes systematik. VII. Florideae. Acta Univ. lund. 21, 1–120, Plate 1.

AGARDH, J.G. (1901). Species Genera et Ordines Algarum. Vol. 3, Part 4, pp. 1–149. (Gleerup: Lund.)

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

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

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

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

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

MAY, V. (1948). The algal genus Gracilaria in Australia. C.S.I.R.O. Bull. 235. pp. 1–64, Plates 1–15.

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.

MUELLER, F.v. (1874). List of the algae of the Chatham Islands collected by H.H. Travers, Esq., and examined by Professor John Agardh, of Lund. Trans. Proc. N.Z. Inst. 6, 208–210.

NELSON, W.A. (1987). The New Zealand species of Gracilaria Greville (Rhodophyta, Gigartinales). N.Z. J. Bot. 25, 87–98.

SONDER, O.G. (1845). Nova Algarum genera et species, quas in itinere ad oras occidentales Novae Hollandiae, collegit L. Preiss, Ph.Dr. Bot. Zeit. 3, 49–57.

SONDER, O.W. (1848). Algae. In Lehmann, C., Plantae Preissianae. Vol. 2, pp. 161–195. (Hamburg.)

WITHELL, A.F., MILLAR, A.J.K. & KRAFT, G.T. (1994). Taxonomic studies of Gracilaria (Gracilariales, Rhodophyta) from Australia. Aust. Syst. Bot. 7, 281–352.

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. 6.

Figure 6 image

Figure 6   enlarge

Fig. 6. Gracilaria flagelliformis (A, B, AD, A22113; C–E, AD, A14146; F, AD, A50580; G, AD, A59736). A. Habit. B. Transverse section of young branch. C. Transverse section of old branch with secondary cortical thickening. D. Section of a (broken) cystocarp. E. Section of a carposporophyte with carposporangia on left and a small fusion cell on lower right. F. Section near base of a cystocarp with traversing nutritive cells from carposporophyte to pericarp. G. Section of thallus with young tetrasporangia.

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