Eucheuma denticulatum (Burm.f.) Collins & Herv.
Family
Solieriaceae
Synonyms
Fucus denticulatus Burm.f., Fucus spinosus L., Eucheuma spinosum J. Agardh (nom. illeg.), Eucheuma muricatum (S.G. Gmelin) Weber Bosse.
Vernacular Names
Usually the vernacular names are common names for all Eucheuma and Kappaphycus spp.
| Indonesia | Agar-agar, agar besar (common names for all Eucheuma and Kappaphycus spp.), spinosa (common commercial name for all Eucheuma spp., especially for E. denticulatum). |
| Philippines | Ruprupuuk (Ilocano), guso (Visayan), canot-canot (Ilocos Norte). |
| China | Chilints’ai, qilinca, gilin cai. |
Geographical Distributions
Eucheuma denticulatum originally occurred only in the Indian Ocean (along the east coast of Africa from Natal to Djibouti, although it was probably only recently introduced into the latter country, India, Bangladesh, most island groups in the Indian Ocean, including small islands in northern Australia), Southeast Asia and in neighbouring parts of the western tropical Pacific (as far as New Caledonia). It has recently been distributed further eastward by man into the Pacific at least as far as Hawaii, Micronesia (Pohnapei) and Christmas Island in easternmost Kiribati. In Southeast Asia, it occurs in Peninsular Malaysia, Singapore, Indonesia (originally especially in the Moluccas), the Philippines and Vietnam. In Indonesia, farming trials with E. denticulatum were carried out before 1984 but failed. Nowadays, the largest production area is around Bali.
Description
This perennial plant is with thalli that forms low, rigid and caespitose clumps.
The primary branches are terete or cylindrical and bear 1-8 mm long spinose determinate branchlets whorls. It branches at predictable intervals that form distinct ‘nodes’ and ‘internodes’ especially towards the terminal portion of branches. The branchlets are sometimes developing into secondary cylindrical laterals. The cross-section of branch reveals a dense cylindrical core of thick-walled and very small rhizoidal cells at the centre of medulla.
The cystocarps are borne near the tips of lateral spines. The tetrasporangia are zonate and embedded in cortex. The spermatangia form surface sori.
Ecology / Cultivation
E. denticulatum is commonly found growing strongly attached to coralline gravelly-rocky or coarse sandy-rocky substrates at the intertidal to the upper (shallow) subtidal zone on the reefs exposed to moderate wave-action or strong tidal currents, where it may forms thick clumps or beds. The fusion of its branches upon coming in contact with each other and its ability to form secondary holdfasts at the tips of branches result in the formation of thick and strongly attached clumps or carpet-like beds which are able to withstand moderate to strong water movement. This alga has never been recorded in calm or protected habitats. It required temperatures for the optimum growth rates are 24-30°C, whereas high solar energy levels are optimal. The preferred pH is 8 and salinity should be 32l. Nitrogen levels should be in a range of 2-4 µg/l and phosphate levels are 0.5-1 µg/l.
Line Drawing / Photograph
References
- Plant Resources of South-East Asia No. 15(1): Cryptogams: Algae.
