Ceratodictyon intricatum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit; 2, detail of vegetative part with tenacula fusing branches (arrow heads); 3, cross-section of a branch; 4, detail of a spatulate tetrasporangial stichidium.

Ceratodictyon intricatum (C. Agardh) R.E. Norris

Protologue: S. Afr. J. Bot. 53: 245 (1987).

Family: Rhodymeniaceae

Chromosome number: 2n= unknown

Synonyms

• Sphaerococcus intricatus C. Agardh (1822),
• Gelidium intricatum (C. Agardh) Kütz. (1849),
• Gelidiopsis intricata (C. Agardh) Vickers (1905).

Origin and geographic distribution

C. intricatum occurs in tropical and subtropical regions in the Indian and Pacific Oceans. Its occurrence in the Atlantic Ocean is not certain and depends on taxonomic interpretation whether or not the circumtropical C. variabile (J. Agardh) R.E. Norris belongs to the same species. In South-East Asia C. intricatum has been recorded in Burma (Myanmar), the Pacific coasts of Thailand, the Philippines, eastern Indonesia and Papua New Guinea.

Uses

In the Philippines C. intricatum is locally used as a vegetable.

Properties

C. intricatum contains agar.

Description

• Thalli from bushy, wiry clumps usually mixed with other seaweeds.
• Plant attached to the substrate by rhizoids, greenish to purplish-brown when fresh.
• Lower branches entangled, stoloniferous, connected by tenacula.
• Branching rather sparse, irregular and somewhat subdichotomous; upper branches erect, about 2-6 cm tall, cylindrical, 160-450 μm in diameter, tapering towards the apices; medulla composed of long and narrow cells, 7-10 μm in diameter; outer cortex cells small, 2-5 μm in diameter, inner cortex cells becoming broader, up to 20 μm in diameter, not much elongated; growth by a number of small cells, no distinct apical cell present.
• Tetrasporangial sori in apical, simple or compound, spatulate swollen stichidia, often on elongated unbranched terminal segments; cruciate tetrasporangia about 25 μm × 50 μm, surrounded by tissue of narrow (3 μm) filaments.
• Sexual organs unknown.

Other botanical information

All Ceratodictyon spp. recorded from the area, except C. spongiosum Zanardini, are possibly subspecies of C. intricatum. The placement of Ceradictyon Zanardini in the family Rhodymeniaceae of the order Rhodymeniales supersedes 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

C. intricatum is a common component of the algal turfs on rocky substrates in the protected portions of the reefs. It may form intricate clumps in tide pools, on rocky ledges or on top of coral colonies growing in very shallow positions or becoming emerged. These somewhat cartilaginous clumps occasionally become detached from their substrate and are washed onto the coasts.

Propagation and planting

There is no known phycoculture of C. intricatum.

Harvesting

C. intricatum is harvested only by hand for direct local use.

Handling after harvest

C. intricatum is used fresh.

Prospects

C. intricatum contains agar and might be a potential source of this substance.

Literature

• 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.
• N'Yeurt, A.D.R., 1996. A preliminary floristic survey of the benthic marine algae of Rotuma Island. Australian Systematic Botany 9: 361-490.
• Price, I.R. & Kraft, G.T., 1991. Reproductive development and classification of the red algal genus Ceratodictyon (Rhodymeniales, Rhodophyta). Phycologia 30: 106-116.
• Trono Jr, G.C. & Ganzon-Fortes, E.T., 1980. An illustrated seaweed flora of Calatagan, Batangas, Philippines. Filipinas Foundation Inc. & University of the Philippines, Marine Science Center, Metro Manila, The Philippines. 114 pp.

Sources of illustration

Norris, R.E., 1987. The systematic position of Gelidiopsis and Ceratodictyon (Gigartinales, Rhodophyceae), genera new to South Africa. South African Journal of Botany 53: fig. 11 & 12, p. 243 (detail of vegetative part and cross-section of branch); N'Yeurt, A.D.R., 1996. A preliminary floristic survey of the benthic marine algae of Rotuma Island. Australian Systematic Botany 9: fig. 192, p. 485 (tetrasporangial stichidium); Trono, G.C. & Ganzon-Fortes, E.T., 1980. An illustrated seaweed flora of Calatagan, Batangas, Philippines. University of the Philippines, Marine Science Center & Filipinas Foundation, Manila, The Philippines. Fig. a, p. 87 (habit). Redrawn and adapted by P. Verheij-Hayes.

Authors

• W.F. Prud'homme van Reine