Valonia aegagropila (PROSEA)

Plant Resources of South-East Asia Introduction

List of species

1, habit; 2 & 3, portions of thallus with vesicles; 4, longitudinal section of a thallus (somewhat diagrammatic); 5, fertile gametangia; 6, biflagellate gametes with eye-spot; 7, young two-celled germling with palmate rhizoid; 8, germling with a single vesicle and several filamentous rhizoids; 9, young vesicle with filamentous rhizoids and secondary vesicles, separated from the primary vesicle by lenticular cell walls; 10, quadriflagellate zoospores with eye-spot.

Valonia aegagropila C. Agardh

Protologue: Spec. alg. 1(2): 429-430 (1823) [1822-1823].

Family: Valoniaceae

Chromosome number: 2n= unknown

Origin and geographic distribution

V. aegagropila is widely distributed in tropical and subtropical areas. In South-East Asia it is common in Burma (Myanmar), Thailand, Vietnam, Malaysia, Singapore, the Philippines and Papua New Guinea.

Uses

V. aegagropila is used as human food, mainly in salads.

Properties

Valonia C. Agardh may contain siphonoxanthin and siphonein. High concentrations of heavy metals have been recorded for rhizoids of Valonia spp.

Description

• Thalli dark green to brownish-green, coenocytic, at first attached, later often free, eventually forming masses, composed of large vesicular clavate branches, 3-13 mm × 2-4 mm.
• Vesicles (segments) slightly constricted at base, arranged in layers with 2-5 daughter vesicles arising from parent vesicle.
• Life cycle diplo-haplontic and isomorphic.

Growth and development

Biflagellate gametes in V. aegagropila , produced by transformed vesicles (gametangia) on dioecious gametophytes, fuse by isogamy. The quadriflagellate zygote soon settles and forms an isomorphic sporophyte, of which vesicles can transform into sporangia. The quadriflagellate zoospores, when released from the sporangia, settle to produce new gametophytes. Settled zygotes and zoospores first form palmate rhizoids. The large apical cell of a germling transforms into a vesicle, while the basal cell forms the primary filamentous rhizoid. From the vesicle new filamentous rhizoids as well as new vesicles arise, separated from the original vesicle by lenticular cell walls.

Ecology

V. aegagropila is generally found in calm and sheltered habitats such as shallow reef flats and lagoons. It is attached to rocky/solid substrate where it forms a thick crust made up of elongate clavate vesicles. Later the crust may be detached from the substrate and form one of the common components of drift, accumulated in shallow hollows on the reef flat or on shore.

Propagation and planting

V. aegagropila is not known in phycoculture.

Harvesting

V. aegagropila is only hand-collected.

Handling after harvest

V. aegagropila is always used fresh. The frequently found washed up specimens have to be carefully cleaned in seawater before they can be used as food. When using freshwater to clean the alga, the vesicles may explode.

Prospects

Large-scale use of V. aegagropila as food in the future is unlikely.

Literature

• Enomoto, S. & Miyazato, K., 1994. Valonia aegagropila (Roth) C. Agardh. In: Hori, T. (Editor): An illustrated atlas of the life history of algae. Vol. 1, Green algae. Uchida Rokakuho Publishing Co., Tokyo, Japan. pp. 252-253.

Sources of illustration

Enomoto, S. & Miyazato, K., 1994. Valonia aegagropila (Roth) C. Agardh. In: Hori, T. (Editor), 1994. An illustrated atlas of the life history of algae. Vol. 1. Green algae. Uchida Rokakuho Publishing Company, Tokyo, Japan. Plate 124, p. 252 (details life cycle); Taylor, W.R., 1960. Marine algae of the eastern tropical and subtropical coasts of the Americas. University of Michigan Press, Scientific Series, Vol. 21, Ann Arbor, Michigan, United States. Plate 7, fig. 6, p. 677 (portion of thallus); 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. 6, p. 213 (habit, portion of thallus). Redrawn and adapted by P. Verheij-Hayes.

Authors

• G.C. Trono Jr