Electronic Flora of South Australia Family Fact Sheet

Tribe PTEROSIPHONIEAE Falkenberg 1901: 261

Phylum Rhodophyta – Family Rhodomelaceae

Thallus erect (often with a prostrate base) or largely prostrate, branching bilateral with discrete, alternate, terete to compressed, distichous laterals, or flat and elongate with short marginal determinate laterals, or branched with foliose rounded apices. Branches one cell thick with a small-celled cortex, or 2 cells thick and ecorticate, with or without a midrib. Structure. Apical cells dividing transversely to form axial cells, with the subapical cells dividing obliquely to form alternate distichous laterals. Frond apices with a single apical cell or a margin of several to numerous apical cells, each forming polysiphonous systems congenitally fused at their base to the axis, or fused along their whole length to form flat fronds; pericentral cells 4 to numerous, in some genera transversely divided. Trichoblasts rare and associated only with sexual reproduction, or frequent on the thallus surface or margin. Cells generally uninucleate.

Reproduction: Gametophytes usually dioecious. Procarps with a 4-celled carpogonial branch and sterile cells, surrounded by a pericarp prior to fertilization; carposporophyte with a basal fusion cell and branched gonimoblast with terminal carposporangia. Cystocarps usually ovoid, pericarp ecorticate or lightly corticate. Spermatangial organs replacing trichoblasts or branches thereof.

Tetrasporangia in terete lateral branches or in stichidia associated with trichoblast tufts on the thallus margin or surface, spirally arranged and single per segment.

Type genus: Pterosiphonia Falkenberg in Schmitz & Falkenberg 1897: 443.

Taxonomic notes: The Pterosiphonieae include about 10 genera (Hommersand 1963, p. 347), all showing bilateral apical development but not primary dorsiventrality.

References:

FALKENBERG, P. (1901). Die Rhodomelaceen des Golfes von Neapel und der angrenzenden Meeres-abschnitte. Fauna und Flora des Golfes von Neapel. Monogr. 26. (Friedländer: Berlin.)

HOMMERSAND, M.H. (1963). The morphology and classification of some Ceramiaceae and Rhodomelaceae. Univ. Calif. Pubis. Bot. 35(2), 165–366.

SCHMITZ, F. & FALKENBERG, P. (1897). Rhodomelaceae. In Engler, A. & Prantl, K., Die natürlichen Pflanzenfamilien. T.1. Abt. 2, pp. 421–480. (Englemann: Leipzig.)

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

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

KEY TO GENERA OF PTEROSIPHONIEAE

1. Thallus slender, pinnately branched with discrete determinate lateral branches arising alternately 2–4 axial segments apart, with their bases congenitally fused with the axis for a few segments only	PTEROSIPHONIA
1. Thallus broad or foliose, prostrate or erect, with one or usually many apical cells producing alternate lateral branches congenitally fused for all or most of their length	2
2. Thallus prostrate to assurgent, 0.5–4 cm long, little branched or regularly pinnate and spinous	3
2. Thallus erect, robust, (3–) 5–40 cm high and 3–20 mm broad	4
3. Thallus prostrate, 0.5–4 cm long, 2–4 mm broad, foliose and slightly branched	SYMPHYOCLADIA
3. Thallus assurgent, pinnate with alternate, spinous, marginal branches	HETEROSTROMA
4. Fronds branched, linear, axes corticated, with a midrib and regularly spinous margins, axial cells with 6 pericentral cells, remaining undivided transversely; thallus mostly 1 cell thick plus a small-celled cortex	DICTYOMENIA
4. Fronds foliose, ecorticate, with or without a midrib, axial cells with 4 pericentral cells, dividing transversely; thallus 2 cells thick	POLLEXFENIA

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