Rhodophyta RHODOPHYTA - Red algae

Subclass FLORIDEOPHYSIDEAE

Order NEMALIALES

HELMINTHOCLADIACEAE

Liagora farinosa Lamouroux, 1816

FAO names: En - Slimy liagora.

Diagnostic characters: Thallus soft and lubricous, pinkish in colour, lightly calcified, farinous and attachedby a small discoid holdfast. Branches numerous, terete, about 1.5 mm in diameter. Branching basicallydichotomous, interdichotomal segments decreasing towards the terminal portion of the thallus. Apices ofbranches fork into very short acute terminal branchlets. Assimilatory filaments terete, about 445 µm longand 30 µm broad; the cells nearly moniliform throughout. Antheridia borne in capitate clusters at the tipsof the assimilatory filaments.Size: Thalli to about 13 cm in height.Habitat, biology, and fisher-ies: Found in shallow water,growing on rocks or old coralsin moderately sheltered loca-tions. Utilized for human con-sumption.Distribution: Commonly foundin tropical and subtropical ar-eas, including the Philippines,Viet Nam, Thailand, the Indo-Malayan Archipelago, andChina.

(after Trono, 1986)

76 Seaweeds

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Order BONNEMAISONIALES

BONNEMAISONIACEAE

Asparagopsis taxiformis (Delile) Trevisan, 1845

FAO names: En - Red sea plume.

Diagnostic characters: Thalli erect, greenish to red in colour, feathery or plumose, arising from a creepingstolon and attached by rhizoids to solid substrates. Central axis terete, bearing plumose branches at itsupper 1/2 to 2/3 portion; the plumose branches are composed of numerous fine and delicate determinatebranchlets which are densely disposed around an axis. Cystocarps subspherical or ovate, bright red incolour and borne at the apices of the short branchlets.Size: Thalli up to 13 cm in height.Habitat, biology, and fisheries: Grows on solid substrates on reef or rocky shores exposed to moderatelystrong water movement. Utilized for human consumption and animal feed; source of protein and used asmedicine (antibiotic, antimicrobial).Distribution: Tropical to sub-tropical in distribution andfound in the Indo-Malayan Ar-chipelago, the Philippines,Thailand, China, Taiwan Prov-ince of China, Viet Nam, andwestern Pacific islands.

(after Trono, 1986)

Rhodophyta 77

GALAXAURACEAE

Scinaia hormoides Setchell, 1914

FAO names: En - Moniliform sea moss.

Diagnostic characters: Thalli erect, red to deep purple in colour, attached by a small discoid holdfast.Stipe short and hard texture giving off branches which are deeply constricted at regular intervals givingrise to vesicular, globose segments (moniliform), 5 mm broad and 7 mm long. Cross-section of a segmentshows a medulla of loose strands of slender non-pigmented medullary filaments and a cortex of 2 layersof cells, the outer epidermal layer made up of firmly coherent non-pigmented cells, the inner layer consistingof ovoid to elongate pigmented cells.Size: Thalli up to 7 cm in height.Habitat, biology, and fisheries: Grows in rocky wave-exposed areas of reef or rocky shores. Utilized forhuman consumption, obtained from natural stocks; also a good source of agar.Distribution: Reported fromthe Philippines, Indonesia,and Malaysia.

(after Trono, 1986)

globose segments

discoid holdfast

78 Seaweeds

Order GELIDIALES

GELIDIACEAE

Gelidiella acerosa (Forsskål) Feldmann and Hamel, 1934

FAO names: En - Chaffweed; Fr - Menue paille marine; Sp - Pajilla marina.

Diagnostic characters: Thalli form wiry mats or clumps attached by rhizoids arising from creeping stolons.Colour yellow-brown to greenish brown when inhabiting tidepools or upper intertidal areas with clear andshallow water, and reddish to purple in shaded upper subtidal and lower intertidal areas. Branches erect,decumbent or prostrate, composed of a terete to compressed central axis and pinnately arranged, filiformlateral branchlets (ramuli) which are upcurved and acuminate, 1 to 6 mm long, and generally decrease inlength towards the distal portion of the axes. Few lateral branchlets may develop that give rise to seconddegree ramuli. In fertile plants, swollen stichidia are formed at the apices of the lateral branchlets.Size: Branches up to 9 cm in length.Habitat, biology, and fisheries: Inhabits shallow waters of the intertidal and upper subtidal zones. Grows inexposed or shaded areas, attached to calcareous substrates such as coralline rocks, rocks covered by crustosealgae, and on sandstones or shells of molluscs. Also found in tidepools with relatively high changes in watertemperature, pH, salinity and degree of exposure to air are influenced by tide. Used for human consumptionand prepared as salad, dessert gel, or agar jelly. One of the most important raw materials for the manufactureof agar used in pharmaceutical industries, paints, varnishes, electric bulbs, and photographic films; also animportant ingredient in milk products, jams, marmalades, and ice cream;used as culture medium in bacteriology,agar plates in electrophoresis, and other laboratory uses.Distribution: Mostly tropical in distribution.Found in the Red Sea, on the eastern andwestern sides of the Pacific Ocean, the Gulfof Mexico, the Caribbean Sea and otherparts of the Atlantic Ocean;also in the south-ern part of Japan, the Indian Ocean, theIndo-Malayan Archipelago, the South ChinaSea, the Philippines, and Viet Nam.

(after Trono, 1986)

pinnatearrangementof branchlets

terminal portion of branch

Rhodophyta 79

Order CRYPTONEMIALES

CRYPTONEMIACEAE

Halymenia dilitata Zanardini, 1851

FAO names: En - Red sea lettuce.

Diagnostic characters: Thalli very delicate, thin, bright red to orange-red. Blade whole or lobed, marginruffled; cross-section of the blade shows a medulla consisting of thin cylindrical branched filaments andganglion-like cells. Cortex made of branched anticlinially arranged filaments consisting of pigmented cells.Size: Thalli up to 20 cm in length.Habitat, biology, and fisheries: Attached to rocky substrate in lower intertidal shaded areas or in uppersubtidal zones exposed to moderate water movement. Utilized for human consumption and a source ofcarrageenan.Distribution: Reported fromthe Philippines, China, andTaiwan Province of China.

80 Seaweeds

Halymenia durvillaei Bory de Saint Vincent, 1828

FAO names: En - Branched halymenia.

Diagnostic characters: Thalli large and bushy, red-orange or purple in colour, soft cartilaginous and slimywhen fresh, attached to rocky substrates by a discoid holdfast. Stipe short, supporting 2 to 4 main axeswhich are 5 to 15 mm wide, branching pinnately-alternately 4 to 5 times. Branches flattened, their diameterdecreases with the increasing degree of branching. Ultimate branchlets slender and linear with acuminatetips, sometimes forcipate. Margins of the fronds serrate, surfaces of the axis provided with few spine-likeprojections. Cross-section of frond shows ganglion-like cells in the medulla connecting the other cells.Cortex consisting of more than 5 layers of very small ovoid or elongated pigmented cells.Size: Thalli to about 35 cm in height.Habitat, biology, and fisheries: Commonly found attached to rocks in lower intertidal to upper subtidalareas which are moderately exposed to wave action. Utilized for human consumption and a source ofcarrageenan.Distribution: Distributed inthe western Pacific and Indo-Malayan Archipelago, includ-ing Thai land, Viet Nam,southern China, Taiwan Prov-ince of China, and the Philip-pines.

(after Trono, 1986)

discoid holdfast

flattened branches

Rhodophyta 81

Order CORALLINALES

CORALLINACEAE

Cheilosporum cultratum (Harvey) Aresschoug, 1852

FAO names: En - Calcified sea moss.

Diagnostic characters: Thalli highly calcified, pinkish to greyish in colour, forming di- to trichotomousdecumbent branches. Branches compressed to flattened, 1.0 to 3.0 mm wide, composed of sagittate segmentswith a prominent midrib, and wing-like lateral extensions which are mostly broadly spinose, gradually or abruptlytapering to acute or acuminate outer tips;some segments have broader wings with truncate, undulate, or toothedouter tips;segments may bear 1 or 2 conceptacles with sharp, horn-like acutely filiform or mucronate processes.Size: Thalli up to 3 cm in length.Habitat, biology, and fisher-ies: Grows on rocks or inpools in the midlower interti-dal zone; forms clumps inshallow subtidal areas ofwave-swept shores.Distribution: Mainly distrib-uted in the tropical westernPacific and found in South Af-rica, China, Taiwan Provinceof China, Viet Nam, Indo-Ma-layan Archipelago, Thailand,and the Philippines.

calcifiedflattenedsegments

(after Trono and Fortes, 1988)

detail of decalcified segmentshowing cell arrangement

flattened wingof segment

tetrasporangia

wing of segment

82 Seaweeds

Order GIGARTINALES

RHIZOPHYLLIDACEAE

Portieria hornemannii (Lyngbye) P.C. Silva, 1987

FAO names: En - Clawed sea moss.

Diagnostic characters: Thalli small, bright orange to red and composed of erect, overlapping fronds thatarise from a small discoid holdfast. Branching in 1 plane, irregularly pinnate-alternate, forming roundedaxils. Diameter of the primary branches not exceeding 7 mm. Tips of the terminal branches at the distalportion of the thallus slightly expanded with enrolled tips. Basal lateral branchlets provided with simpleacute teeth.Size: Thalli about 5.5 cm in height.Habitat, biology, and fisheries: Attached to rocks or dead corals in upper to lower subtidal areas exposedto moderate to strong water movement. Source of carrageenan.Distribution: Reported fromthe Phi l ipp ines, China(Guangdong Province), andother parts of the Indo-WestPacific.

(after Trono, 1986)terminal portion of branch

discoid holdfast

claw-liketips

Rhodophyta 83

GRACILARIACEAE

Gracilaria arcuata Zanardini, 1860

FAO names: En - Arcuate gracilaria.

Diagnostic characters: Thalli erect, cartilaginous, greenish purple, with a discoid holdfast. Primary andsecondary branches prominent, mostly arcuate, terete throughout, slightly constricted at the base. Branch-ing on the main axes generally secund. Terminal branches giving rise to 2 or 3 short, stubby, spinosebranchlets at their distal portions.Size: Thalli up to 10 cm in height.Habitat, biology, and fisheries: Grows in shallow subtidal areas attached to coral rocks and fragments,and shells; utilized for human consumption and a source of agar; used in wastewater purification, containsgrowth regulator substances similar to auxin, gibberellin, and cytokinin; also used as manure for coconutsand coffee bushes in Hainan, India, and Sri Lanka.Distribution: Mainly tropicalin distribution and found inChina, Japan, Korea, Indone-sia, the Philippines, Tonga Is.,Samoa, Sri Lanka, Mauritius,the Red Sea, and Mediterra-nean coasts.

arcuate mainbranches

(after Trono, 1986)

stubby spinosebranchlets

generalized distribution for Gracilaria

84 Seaweeds

Gracilaria edulis (Gmelin) Silva, 1952

FAO names: En - Dichotomously branched gracilaria.

Diagnostic characters: Thalli erect, cartilaginous, greenish brown to dark brown, or purple in colour,attached by a small discoid holdfast. Branching basically repeatedly dichotomous and divaricate. Branchesterete, 1.5 to 2.2 mm in diameter, tapered and characteristically bifurcate at the terminal portions.Size: Thalli up to 14 cm in height.Habitat, biology, and fisheries: Forms clumps in sandy-muddy or rocky intertidal areas, in dense tuftswhen growing on fish cages, and in loose fastigiate tufts on rocks in clear water. Utilized for humanconsumption and as a source of agar; used as manure for coconuts and coffee bushes in Hainan, India,and Sri Lanka.Distribution: Reported in thewestern Pacific from Singa-pore, Thailand, Malaysia, andthe Philippines; also in the In-dian Ocean.

bifurcate tipsof branches

(after Trono, 1986)

generalized distribution for Gracilaria

Rhodophyta 85

Gracilaria eucheumoides Harvey, 1860

FAO names: En - Prostrate gracilaria.

Diagnostic characters: Thalli greenish brown to purple in colour, forming loose or thick prostrate clumpson rocky substrates attached by means of hapters. Branches distinctly compressed, up to 1 cm wide,branching irregular. Margin of the flattened branches with coarse teeth or short spines.Size: Thalli up to 12 cm in length.Habitat, biology, and fisheries: Grows strongly attached to rocks or coral fragments in lower intertidal toupper subtidal areas, exposed to moderate or strong water turbulence. Economically important as sourceof agar and for human consumption (salad or stew mixed with vegetables); used as manure for coconutsand coffee bushes in Hainan, India, and Sri Lanka.Distribution: Widespread inthe tropics, including Japan,Australia, China, Indonesia,Philippines, and Morocco.

flattened brancheswith marginal teeth

(after Trono, 1986)

generalized distribution for Gracilaria

86 Seaweeds

Gracilaria heteroclada Zhang and Xia, 1988

FAO names: En - Percurrent gracilaria.

Diagnostic characters: Thalli erect, brittle when fresh, dark brown to purple and sometimes olive greenin colour, purple to black when dried. Main branches percurrent with many spinose determinate branchlets.Branchlets distinctly smaller in diameter than main axes; branch bases not constricted. Cortex thin,composed of 1or 2 layers of regularly spherical to oval cells. Medullary cells large, thin-walled, 4.25 to9.5 µm thick; transition of cell size from medulla to cortex abrupt. Cystocarp rostrate, hemispherical,somewhat embedded and unconstricted at the base. Pericarp thin, with 6 to 8 layers of cells, 65 to 137 µmthick. Nutritive filaments absent. Carpospores 23 to 38 µm in diameter, centre of gonimoblast composedof small ovoid cells; carpospore initials elongated. Spermatangia superficial, on elongated outer corticalcells. Tetraspores broad and rounded.Size: Thalli up to 60 cm in height.Habitat, biology, and fisheries: Grows on shells or gravel on mud flats and in tidepools, or canals inmidtidal to low intertidal areas. Utilized for human consumption and a source of agar.Distribution: Reported fromChina, the Philippines, andViet Nam.

percurrentmain axis

(after Trono et al., 1983)

Rhodophyta 87

Gracilaria manilaensis Yamamoto and Trono, 1994

FAO names: En - Filiform sea moss.

Diagnostic characters: Thalli reddish brown to purple in colour, erect, loosely branched, attached to shellsand debris by a very small discoid holdfast. Branches 0.8 to 1.9 mm in diameter, terete throughout, slender,gradually tapering towards filiform apices, distinctly constricted at the base; soft and easily broken whenfresh. Cortex composed of 1 or 2 layers of spherical to cuboidal cells, 9x4.75 to 13x8.25 µm in size.Medullary cells large, 52 to 746 µm in diameter; cell walls 3 to 4.5 µm thick; cell size transition from medullato cortex abrupt. Cystocarps semi-globose, unconstricted at the base and distributed on more maturebranches, 0.8 to 0.9 mm in diameter. Pericarp consisting of 6 to 10 layers of cells, 103 to 188 µm thick;outermost cells round to oval and anticlinally arranged, inner layers periclinally arranged, becomingflattened towards the gonimoblast. Nutritive filaments abundant between pericarp and gonimoblast.Carpospores 15 to 20 µm in diameter, gonimoblast centre composed of few large parenchyma cells.Spermatangial cavities oval, cup-shaped to deep oval (verrucosa type) and 36.5 to 104 µm deep.Tetraspores prominent, sometimes protruding from the cortex, 26.26x18 to 39.25x31.75 µm in size.Size: Thalli up to 54 cm in length.Habitat, biology, and fisheries: Grows attached to pebbles, shells and stones on muddy bottoms inshallow nutrient-rich water. Utilized for human consumption and raw material for agar manufacture.Distribution: Endemic to thePhilippines.

small discoidholdfast

(after Trono, 1986)

88 Seaweeds

Gracilaria salicornia (C. Agardh) Dawson, 1854

FAO names: En - Segmented gracilaria.

Diagnostic characters: Two forms are distinguished, depending on the type of habitat. In areas where thewater is clear, calm, and exposed to full sunlight, the thalli are bright orange with branching dichotomousto tetrachotomous divaricate; branches distinctly divided into terete, subclavate to clavate segments,swollen at the distal end and constricted at the base. In areas where the water is turbid and the movementis moderate to strong, thalli are dark green to greenish brown, forming prostrate clumps on the substrate;branching irregularly subdichotomous to trichotomous to alternate; branches not distinctly divided intoclavate segments except at the terminal portions and are shorter.Size: Thalli up to 8 cm in height.Habitat, biology, and fisheries: Attached to solid substrate such as coral fragments, shells, pebbles,stones, rocks, gravel, or mangrove roots, in clear to turbid waters. Usually found in protected portions ofreef flats not exposed to the full impact of wave action. Utilized for human consumption and a source ofagar, but its agar is of poorquality; also used as manurefor coconuts and cof feebushes in Hainan, India, andSri Lanka.Distribution: Mainly tropicalin distribution and found inChina, Taiwan Province ofChina, Viet Nam, Singapore,the Philippines, Malaysia, In-dia, Thailand, and westernPacific islands.

(after Trono et al., 1983)

club-shapedsegments

generalized distribution for Gracilaria

Rhodophyta 89

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