Difference between revisions of "Ceratodictyon spongiosum (PROSEA)"

Latest revision as of 21:06, 8 June 2023

Plant Resources of South-East Asia Introduction

List of species

1, habit of the symbiotic association; 2, detail of the algal component, with anastomoses; 3, detail of tetrasporangial stichidia; 4, detail of a cross-secton of a tetrasporangial stichidium, with tetrasporangia and a hair; 5, detail of a cross-section of a spermatangial stichidium, with spermatangia occurring single or in small chains on cortex cells.

Ceratodictyon spongiosum Zanardini

Protologue: Nuovo Giorn. Bot. Ital. 10: 37 (1878).

Family: Rhodymeniaceae

Chromosome number: 2n= unknown

Synonyms

Marchesettia spongioides Hauck (1882).

Origin and geographic distribution

C. spongiosum is often common in tropical and subtropical regions in the Indian and Pacific Oceans. In South-East Asia it has been recorded in Thailand, Malaysia, Singapore, Indonesia, the Philippines and Papua New Guinea.

Uses

At present C. spongiosum has no uses.

Properties

C. spongiosum contains agar.

Description

• The symbiotic association of the sponge Sigmadocia symbiotica Bergquist & Tizard and the alga C. spongiosum forms clumps of 15-30(-70) cm in diameter and 5-15 cm tall. These associations are green-brown to purple, distinctly sponge-like, subcylindrical or compressed, hard and tough.
• Branching very irregular and often anastomosing, 5-10(-20)mm in diameter and with many ostioles of the sponge. Intertwining and anastomosing algal axes form a dense reticulum within the sponge cover. Specimens anchored at numerous points to solid substrates by slightly splayed but otherwise unmodified bases or lateral extensions of major axes (no expanded discs or thickened holdfasts).
• Algal axes terete, 100-300(-400) μm in diameter, with a single-layered outer cortex, a pseudoparenchymatous inner cortex and a medulla of a compact core of narrow filamentous cells; distinct apical cell absent, growth by small cells in dome-shaped, multiaxial apex.
• Life cycle triphasic, diplo-haplontic and isomorphic.
• Tetrasporangial sori in apical, aggregated, swollen, cylindrical stichidia, about 1.5 mm long, on modified terminal algal branches projecting into sori from the tips of the branches of the symbiotic association; tetrasporangia irregularly decussate, about 10-15 μm × 20-25 μm, surrounded by tissue of narrow (3 μm) anticlinal rows of cortex cells.
• Gametophytes dioecious; male ones forming swollen, exerted axes superficially resembling tetrasporangial stichidia, although more mucilaginous and covered by spermatangial mother cells, each forming 1-2 distal spermatangia; female ones with dense clusters of terete to slightly flattened protruding terminal branches, simple or sparingly branched, covered by aggregates of cystocarps with often partly confluent pericarps.
• Mature cystocarps protuberant, about 600 μm in diameter, bluntly conical, with apical ostiole.

Growth and development

The algal (C. spongiosum) and sponge partners reproduce completely independently of one another. It is not known when, or how, the symbiosis is established. Sponge-free algal growth has been established in laboratory culture, but the sponge partner has never been found free-living, and attempts to maintain it separately in laboratory culture have failed.

Other botanical information

Other Ceratodictyon spp. recorded from the area, except C. spongiosum, are possibly subspecies of C. intricatum (C. Agardh) R.E. Norris. The placement of Ceratodictyon Zanardini in the family Rhodymeniaceae of the order Rhodymeniales replaces earlier inclusion in the family Gracilariaceae of the order Gigartinales. The relationship between Ceratodictyon and Gelidiopsis F. Schmitz and their taxonomic placement is not yet solved.

Ecology

The symbiotic association of C. spongiosum and Sigmadocia symbiotica typically occurs on intertidal coral reef flats and subtidal reef slopes, but has also been recorded at greater depths (up to 100-140 m).

Propagation and planting

There is no known phycoculture of C. spongiosum.

Prospects

C. spongiosum may become a source of fine chemicals and pharmaceuticals, especially because sponges are known to contain many interesting biopharmaceutical compounds. Most sponges are difficult to find regularly and in suitable quantities, but because of the symbiotic association with C. spongiosum, Sigmadocia symbiotica can be easily identified and collected.

Literature

• Cribb, A.B., 1983. Marine algae of the southern Great Barrier Reef-Rhodophyta. Australian Coral Reef Society Handbook No 2. 173 pp. + 71 plates.
• Norris, R.E., 1987. The systematic position of Gelidiopsis and Ceratodictyon (Gigartinales, Rhodophyceae), genera new to South Africa. South African Journal of Botany 53: 239-246.
• Price, I.R., Fricker, R.L. & Wilkinson, C.R., 1984. Ceratodictyon spongiosum (Rhodophyta), the macroalgal partner in an alga-sponge symbiosis, grown in unialgal culture. Journal of Phycology 20: 156-158.
• Price, I.R. & Kraft, G.T., 1991. Reproductive development and classification of the red algal genus Ceratodictyon (Rhodymeniales, Rhodophyta). Phycologia 30: 106-116.

Sources of illustration

Cribb, A.B., 1983. Marine algae of the southern Great Barrier Reef - Rhodophyta. Australian Coral Reef Society Handbook No 2. Plate 12, fig. 3 & 4 (habit and detail of algal component); Price, I.R. & Kraft, G.T., 1991. Reproductive development and classification of the red algal genus Ceratodictyon (Rhodymeniales, Rhodophyta). Phycologia 30: fig. 3, p. 108 (photo of detail of tetrasporangial stichidium); fig. 14, p. 112 (tetrasporangial stichidia and cross-section); fig. 15, p. 112 (cross-section of spermatangial stichidium). Redrawn and adapted by P. Verheij-Hayes.

Authors

• G.C. Trono Jr