Electronic Flora of South Australia Genus Fact Sheet

Genus SCINAIA Bivona-Bernardi 1822: 232

Phylum Rhodophyta – Class Florideophyceae – Order Nemaliales – Family Galaxauraceae

Thallus (gametophyte) erect, terete to slightly compressed, subdichotomously branched, multiaxial, with a medullary core of numerous, slender, branched, filaments usually less than 20% of the thallus diameter in width, producing numerous radiating, branched filaments forming an outer medulla and a cortex 2–4 cells broad, with an outer layer of large, colourless, utricles, with or without rhodoplastic ovoid cells between them.

Tetrasporophyte (in S. forcellata, S. complanata and S. confusa) minute, filamentous, branched; unknown in other species.

Reproduction: Sexual thalli usually monoecious. Carpogonial branches 3-celled with the hypogynous cell bearing 2–4 sterile filaments and the basal cell producing filaments which form a distinct involucre around the carposporophyte. Gonimoblast filaments arising from the fertilized carpogonium, producing carposporangia in short terminal chains, with a basal fusion cell usually present. Cystocarp urceolate, ostiolate, lying within the outer medulla. Spermatangia cut off from short, branched filaments which penetrate between the cortical utricles, or on the vegetative filaments in this position.

Tetrasporophytes reproducing by cruciately divided tetrasporangia.

Life history triphasic with heteromorphic gametophyte and sporophyte.

Type species: S. forcellata Bivona-Bernardi 1822: 232 (see Silva 1992, p. 167).

Taxonomic notes: Scinaia is characterised by the presence of colourless, ovoid to angular, utricles forming the surface layer of the thallus. Huisman (1985) refers both Pseudoscinaia Setchell (1914, p. 120) and Pseudogloiophloea Levring (1953, p. 505; 1955, p. 420) to Scinaia and (Huisman 1985, 1986) includes some 25 species in the genus.

Only three species have been investigated in culture. Boillot (1968, 1969) has shown that the carpospores of S. forcellata germinate to form a filamentous sporophyte bearing cruciately divided. tetrasporangia and a similar situation was shown by Ramus (1969, p. 7) for S. confusa (as Pseudogloiophloea) and by van den Hoek & Cortel-Breeman (1970, p. 457) for S. complanata.

References:

BIVONA-BERNARDI, A. (1822). Scinaia algarum marinarum novum genus. L'Iride, Giorn. Sci. Sicilia 1, 232–234.

BOILLOT, A. (1968). Sur l'existence dun tétrasporophyte dans le cycle de Scinaia furcellata (Tumer)Bivona, Némalionales. C.R. Acad. Sc. Paris 266, Ser D, 1831–1832.

BOILLOT, A. (1969). Sur le développement des tétraspores et l'édification du gamétophyte chez Scinaia furcellata (Tumer)Bivona, Rhodophycées (Némalionales). C.R. Acad. Sc. Paris 268, Sér. D, 273–275.

HOEK, C. VAN DEN & CORTEL-BREEMAN, A.M. (1970). Life-history studies on Rhodophyceae III. Scinaia complanata (Collins)Cotton. Acta Bot. Neerl. 19, 457–467.

HUISMAN, J.M. (1985). The Scinaia assemblage (Galaxauraceae, Rhodophyta): a re- appraisal. Phycologia 24, 403–418.

HUISMAN, J.M. (1986). The red algal genus Scinaia (Galaxauraceae, Nemaliales) from Australia. Phycologia 25, 271–296.

LEVRING, T. (1953). The marine algae of Australia. I. Rhodophyta: Goniotrichales, Bangiales and Némalionales. Arkiv för Bot. Ser. 2, 2, 457–530.

LEVRING, T. (1955). Contributions to the marine algae of New Zealand. I. Rhodophyta: Goniotrichales, Bangiales, Némalionales and Bonnemaisoniales. Arkiv för Bot. Ser. 2, 3, 407–432.

RAMUS, J. (1969). The developmental sequence of the marine red alga Pseudogloiophloea in culture. Univ. Calif Pubis Bot. 52, 1–42.

SETCHELL, W.A. (1914). The Scinaia assemblage. Univ. Calif Pubis Bot. 6, 79–153.

SILVA, P.C. (1992). Nomenclatural notes on Clemente's Ensayo. Anales Jard. Bot. Madrid 49, 163–170.

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

Author: J.M. Huisman & 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.

KEY TO SPECIES OF SCINAIA

1. Branches regularly moniliform with ovoid segments 6–15 (–17) mm long and 3–5 mm in diameter

S. moniliformis

1. Branches terete or only occasionally constricted, usually 1–3 mm in diameter

2

2. Outer cortex largely composed of truncated, closely adjacent utricles with very few smaller cells reaching the surface

3

2. Outer cortex with large ovoid utricles intermixed with rows of smaller cells giving a rosette appearance in surface view

4

3. Thallus usually 5–20 cm high with branches 1.5–3 (–4) mm in diameter; hypogynous cell with four sterile branches

S. aborealis

3. Thallus 3–10 cm high with branches 0.5–2 mm in diameter; hypogynous cell with two sterile branches, one 1-celled and one 2-celled

S. tsinglanensis

4. Thallus soft, usually (5–) 10–20 cm high, regularly subdichotomous, only two sterile branches on hypogynous cell

S. australis

4. Thallus cartilaginous, 4–6 cm high, proliferous from lower parts, 2–3 sterile branches on hypogynous cell

S. proliferata


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