Dictyopteris jamaicensis (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

habit

Dictyopteris jamaicensis W.R. Taylor

Protologue: Mar. alg. east. trop. subtrop. coasts Amer.: 631, pl. 32, fig. 2 (1960).

Family: Dictyotaceae

Chromosome number: 2n= unknown

• Philippines: laplapayag (also used for Spathoglossum sp.).

D. jamaicensis has been recorded in the Atlantic Ocean (Jamaica) and the Pacific Ocean (Polynesia). In South-East Asia it occurs in Indonesia (Sulawesi) and the Philippines (Luzon, Visayas).

D. jamaicensis is used as a medicine because of its antitumor activity. It is used as food in eastern Polynesia, and this odoriferous seaweed also contains essential oils that can be used to produce products with "sea breeze" smell.

Some Dictyopteris spp. contain an essential oil with a "beach odour", consisting mainly of the non-halogenated sesquiterpenes cadalene and cadinene. In other Dictyopteris spp. there are non-isoprenoid C₁₁ compounds in the essential oil, including cycloheptadienes and dictyopterene as well as a low-viscosity alginate. D. divaricata (Okamura) Okamura contains 10 mg/g (dry weight) vitamin C. D. membranacea (Stackh.) Batters (as D. polypodioides (Desf.) J.V. Lamour.) is used to treat lung diseases and scrofula. D. undulata Holmes and D. divaricata have been found to be potent inhibitors of bee-venom-derived phospholipase A₂.

• Thalli composed of subdichotomous branched straps, forming angles of less than 90°, each with a single lens-shaped apical cell.
• Fronds up to 12 cm tall, dark brown or yellowish-brown, attached by a well-developed holdfast. Straps 4-8 mm across, 2 cell-layers thick, narrowing at distal portion of thallus, with distinct midrib running through entire length of the straps; midrib with polyhedral quadrangular cells in surface view; lateral veins absent; tufts of hairs parallel on both sides of midrib; margin entire to minutely erose-dentate, slightly undulate.
• Life cycle diplo-haplontic and isomorphic.
• Tetrasporangia grouped in sori or scattered over the whole of the fronds, each with 4 non-motile tetraspores.
• Gametophytes dioecious, with oogonia and antheridia (surrounded by rows of paraphyses) grouped in sori.

D. jamaicensis is generally limited in distribution to rocky wave-exposed habitats such as reef crests and slopes as well as in deeper waters (33-73 m), attached to shells and coral fragments. It usually is firmly attached to hard substrates, although detached thalli may also be found among drifting seaweeds.

There is no known phycoculture of D. jamaicensis.

Attached and drifting specimens of D. jamaicensis are collected by hand.

D. jamaicensis is mainly used fresh.

Future studies might result in additional use of D. jamaicensis for the production of pharmaceutical compounds. For this purpose and for further potential use as a provider of essential oils it is recommended that commercial cultivation be started.

• Katayama, T., 1961. Chemical studies on volatile constituents of seaweed. 16. Their phylogenetic and biochemical significance. Bulletin of the Japanese Society of Scientific Fisheries 27: 75-84.
• Moore, R.E., 1977. Volatile compounds from marine algae. Accounts of Chemical Research 10: 40-47.
• Pickenhagen, W., Näf, F., Ohloff, G., Müller, P. & Perlberger, P.C., 1973. Thermal and photochemical rearrangements of divinylcyclopropanes to cycloheptadienes. A model for the biosynthesis of the cycloheptadiene derivatives found in a seaweed (Dictyopteris). Helvetica Chimica Acta 56: 1868-1874.

Trono, G.C., 1986. Philippine seaweeds. In: Guide to Philippine flora and fauna. Vol. 1. Natural Resources Management Center, Ministry of Natural Resources and University of the Philippines. Goodwill Bookstore, Manila, The Philippines. Fig. 57, p. 252. Redrawn and adapted by P. Verheij-Hayes.

• G.C. Trono Jr