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Genus SYNARTHROPHYTON Townsend 1979: 252

Phylum Rhodophyta – Class Florideophyceae – Order Corallinales – Family Corallinaceae – Subfamily Melobesioideae

Thallus encrusting to discoid, warty, foliose or fruticose; epigenous and partially or completely affixed by cell adhesion or envelopment of host axes; genicula absent. Structure pseudoparenchymatous; organisation dorsiventral in crustose portions but radial in protuberant branches; construction monomerous, consisting of a single system of branched, laterally cohering, filaments that collectively contribute to a ventrally or centrally situated core and a peripheral region where portions of core filaments or their derivatives curve outwards towards the thallus surface; cell elongation occurring mainly within actively dividing subepithallial initials that are usually as long as or longer than their immediate inward derivatives; fusions present between cells of contiguous filaments, secondary pit-connections absent; epithallial cells terminating most filaments at thallus surface, distal walls rounded or flattened but not flared; haustoria and trichocytes unknown.

Reproduction: Vegetative reproduction unknown. Gametangia and carposporangia borne in uniporate conceptacles; tetrasporangia borne in multiporate conceptacles that apparently arise from groups of subepithallial initials; gametangia and carposporangia formed on separate thalli from tetrasporangia. Report of bisporangia unconfirmed.

Gametangial thalli monoecious or dioecious; carpogonia and spermatangia produced in separate conceptacles or rarely in the same conceptacle. Carpogonia terminating 2- or 3-celled filaments arising from the female conceptacle chamber floor. Mature carposporophytes apparently composed of a fusion cell (not always evident) and short gonimoblast filaments bearing terminal carposporangia. Both unbranched and branched spermatangial filaments present, borne on the floor, walls and roof of male conceptacle chambers.

Tetrasporangia scattered across the conceptacle chamber floor, roofs formed by filaments interspersed amongst and peripheral to sporangial initials; each mature sporangium containing zonately arranged tetraspores and possessing an apical plug that blocks a roof pore prior to spore release.

Type species: S. patena (Hooker & Harvey in Harvey)Townsend 1979: 252.

Taxonomic notes: Synarthrophyton is represented in southern Australia by a single species, S. patena. This account follows A. Harvey et al. (1994) and May & Woelkerling (1988). A second species, S. schielianum Woelkerling & Foster (1989), has been reported only from the Chatham Islands. Details relating to generic etymology, nomenclature, orthographic variants, etc. are provided by Woelkerling (1988, pp. 210–215). Bisporangial conceptacles, reported by Heydrich (1897b, p. 413) for S. patena (as Lithothamnion), have not been confirmed to occur (A. Harvey & Woelkerling 1994).


HARVEY, A.S., WOELKERLING, W.J. & WILKS, K.M. (1994). The genus Synarthrophyton (Corallinaceae, Rhodophyta) in southern Australia. Phycologia 33, 331–342.

HEYDRICH, F. (1897b). Melobesieae. Ber. dt. bot. Ges. 15: 403–420, Plate 18.

MAY, D.I. & WOELKERLING, W.J. (1988). Studies on the genus Synarthrophyton (Corallinaceae, Rhodophyta) and its type species, S. patena (J.D. Hooker et W.H. Harvey) Townsend. Phycologia 26, 50–71.

TOWNSEND, R.A. (1979). Synarthrophyton, a new genus of Corallinaceae (Cryptonemiales, Rhodophyta) from the southern Hemisphere. J. Phycol. 15, 251–259.

WOELKERLING, W.J. & FOSTER, M.S. (1989). A systematic and ecographic account of Synarthrophyton schielianum sp. nov. (Corallinaceae, Rhodophyta) from the Chatham Islands. Phycologia 28, 39–60.

WOELKERLING, Wm.J. (1988). The Coralline Red Algae. [British Museum (N.H.): London.]

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

Author: W.J. Woelkerling

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.

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