Gelidium spinosum (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

f. elongatum - 1, habit; 2, portion of a vegetative terminal branch; 3, portion of a terminal branch, bearing both a cystocarp (c) and tetrasporangia (t); 4, tetrasporangial ramulus; 5, cystocarpic ramulus; 6, surface view of cortical cells; 7, cross-section of a branch.

Gelidium spinosum (S.G. Gmelin) P.C. Silva

Protologue: Silva, P.C., Basson, P.W. & Moe, R.L., Univ. Calif. Publ. Bot. 79: 141-142 (1996).

Family: Gelidiaceae

Chromosome number: x= 4-5; 2n= (9), 10

Synonyms

• Fucus spinosus S.G. Gmelin (1768),
• F. corneus Huds. var. attenuatus Turner (1819),
• Gelidium latifolium Bornet ex Hauck (1883),
• G. attenuatum Thur. ex Bornet (1892).

Vernacular names

• Indonesia: agar-agar halus (Moluccas), kembang karang (southern coast of Central Java), kades (Garut, southern coast of West Java).

Origin and geographic distribution

G. spinosum is widely distributed from the European North Atlantic (England) to Japan and the tropical Indo-Asian waters. In Indonesia it is found as forma elongatum (A.M. Hatta & Prud’homme) P.C. Silva along the southern coasts of Sumatra, Java and the Lesser Sunda Islands (Bali to Timor). It also occurs along the coast of Peninsular Malaysia.

Uses

Dried G. spinosum is mainly sold to agar factories. In Indonesia, especially in the 1950s, this agarophyte was processed in large quantities by an agar factory in West Java. Traditional uses are as a vegetable and as raw material for making traditional agar jelly. Other raw materials used for agar include Gelidiella acerosa (Forssk.) Feldmann & Hamel, Hypnea and Gracilaria spp.

Production and international trade

Production of G. spinosum in Indonesia is still dependent on natural stocks. In recent years, its contribution to the national agarophyte market has been negligible; most agarophyte materials on the market come from Gracilaria spp. The latter are already cultivated on a large scale, meeting national needs and also being exported.

Properties

An analysis of material of G. spinosum from the south-western coast of Java indicated an agar content of 23.3-27.7%.

Description

• Plants of medium size, less than 10 cm tall, stolons relatively short and cylindrical, attached to hard substrates by peglike haptera, solitary, tufted; frond giving more or less a pyramidal outline; main axial thallus terete, compressed or almost flat, limited-growth thalli terete to slightly compressed with a single apical cell; branching opposite or bi-tetrapinnate.
• Cortical cells crowded, subquadrangular in cross-section; with 4-5 layers of inner cortical cells, subquadrangular to ovate, inwards gradually larger, and a core of medullary cells.
• Internal rhizines mostly concentrated between inner cortical cells, but often distributed amongst the outermost medullary cells.
• Tetrasporangia mostly on short spatulate terminal ramuli, rounded and irregularly arranged.
• Cystocarps large, protruding bulblike, on short flattened terminal ramuli.

Other botanical information

The tropical form of this alga has been named G. spinosum forma elongatum (A.M. Hatta & Prud’homme) P.C. Silva (synonym: G. latifolium forma elongatum A.M. Hatta & Prud’homme).

Ecology

In western Indonesia, G. spinosum inhabits shallow waters of the exposed coastal area typically with hard substrates, strong current and surf. It grows very well on rock-boulders in the lower eulittoral and subtidal zones where the seawater salinity is relatively high, i.e. more than 32‰

Phycoculture

G. spinosum is not commercially cultivated. There are two main obstacles in developing its culture: its small size and the difficulty of attaching vegetative germlings to artificial substrates.

Harvesting

The traditional method of harvesting the natural stock of G. spinosum is by scraping the algae from the substrates. Harvesting of this agarophyte from the southern coast of Java takes place from July to December.

Prospects

The characteristics of the agar of G. spinosum have not been seriously studied yet, but like other tropical gelidioid algae, e.g. Gelidiella acerosa. G. spinosum has good potential for being developed as agar resource, especially if phycoculture were to become feasible.

Literature

• Hatta, A.M. & Prud'homme van Reine, W.F., 1991. A taxonomic revision of Indonesian Gelidiales (Rhodophyta). Blumea 35: 347-380.

Sources of illustration

Hatta, A.M., original drawings (habit, vegetative branch); Hatta, M.A. & Prud'homme van Reine, W.F., 1991. A taxonomic revision of Indonesian Gelidiales (Rhodophyta). Blumea 35: Fig. 7, p. 362 (fertile thallus and all details). Redrawn and adapted by P. Verheij-Hayes.

Authors

• A.M. Hatta & R. Dardjat