Electronic Flora of South Australia Species Fact Sheet
Phylum Rhodophyta – Class Florideophyceae – Order Nemaliales – Family Galaxauraceae
Thallus (Fig. 29D) red-brown, 4–6 cm high, subdichotomously branched every 3–11 mm with proliferous growth from older cut-off branches, branches 0.7–1.5 (–2) mm in diameter, with pointed apices. Holdfast discoid, 1–2 mm across; epilithic. Structure multiaxial, developing a central core of entwined filaments 2–13 µm in diameter, from which radiate medullary filaments 2–3 µm in diameter, with a cortex of 1–2 layers of ovoid rhodoplastic hypodermal cells 10–20 µm in diameter, and an outer layer of ovoid to pyriform utricles 20–30 µm in diameter; numerous smaller cells or utricles surround the larger ones in a rosette surface pattern.
Reproduction: Sexual thalli monoecious. Carpogonial branches (Fig. 28J) 3-celled, developing on outer medullary filaments, with the hypogynous cell producing 2 or 3 sterile branches, usually two 1-celled and one 2-celled, which may divide further, and the basal cell producing 3–4 sterile branches which form the involucre after fertilization. Fertilized carpogonium forming a basal fusion cell and gonimoblast filaments with terminal chains of ovoid carposporangia 5–12 µm in diameter. Cystocarps 150–220 µm in diameter, ostiolate, with a well-developed involucre. Spermatangial branches arising from hypodermal cells, penetrating between the utricles, and producing terminal, ovoid, spermatangia 3–4 µm in diameter.
Type from Nora Creina, S. Aust., 4–6 m deep on small stones (Kraft 4932, 18.ii.1974); holotype in MELU, isotype in AD, A46012.
Distribution: Only known from the type collection.
Taxonomic notes: S. proliferata resembles S. australis in branch diameter, in structure and in most aspects of reproduction. It differs in having proliferations from older branches, possibly following grazing, and in having 2–3 branches from the hypogynous cell instead of two in S. australis. More collections are clearly desirable to support recognition of this species as distinct from S. australis.
HUISMAN, J.M. (1986). The red algal genus Scinaia (Galaxauraceae, Nemaliales) from Australia. Phycologia 25, 271–296.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
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.
Illustrations in Womersley Part IIIA, 1994: FIGS 28J, 29D.
Figure 28 enlarge
Fig. 28. A, B. Scinaia moniliformis (MELU, AM909). A. Carpogonial branch with a one-celled sterile branch (left) and a two-celled sterile branch (right) on the hypogynous cell. B. A later stage than A with a developing gonimoblast. C, D. Scinaia aborealis (MELU, AM918). C. Carpogonial branch with 3 sterile branches on the hypogynous cell. D. Developing gonimoblast. E, F. Scinaia tsinglanensis (MELU, 24299). E. Carpogonial branch with sterile branches on the hypogynous and basal cells. F. Developing gonimoblast. G–I. Scinaia australis (MEL, 612903). G. Surface view of cortex. H. Mature carpogonial branch. I. Developing gonimoblast. J. Scinaia proliferata (MELU, GK 4932). Mature carpogonial branch with several cells derived from the hypogynous cell. [A–J after Huisman 1986.]
Figure 29 enlarge
Fig. 29. A–C. Scinaia australis (A, UC, 74793; B, C, MELU, 22999). A. Holotype, habit. B. Cross section of cortex. C. Section of young cystocarp. D. Scinaia proliferata (MELU, GK 4932, holotype). Habit. E–G. Gloiophloea scinaioides. (E, LD, 32112; F, G, MELU, 22994). E. Holotype, habit. F. Cross section of cortex. G. Section of cystocarp. [A–D as in Huisman 1986; E–G as in Huisman 1985.]
State Herbarium of South Australia