Phylum Rhodophyta: Subtidal Red Seaweeds

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Red seaweeds. Color comes from accessory photosynthetic pigments (phycoerythrin, phycocyanin, allophycocyanin). Depending on relative amounts of these 3 and chlorophyll, plant color can vary from dark red to blue, brown, or greenish.  Corallines deposit calcium carbonate in their cell walls, probably as an anti-grazing defense. Red algal life histories are complex, typically comprising 3 stages, two of which may differ a great deal in appearance (heteromorphic) or appear similar (isomorphic).  The third phase is small and grows epiphytically on one of the others. Estimates of number of living species varies from 5000-6000 to as high as 10,000.

Class Florideophyceae
 Order Gigartinales
 
Callophyllis flabellulata Callophyllis sp. Pugetia firma Erythrophyllum delesserioides Chondracanthus corymbifera Gymnogongrus chiton Sarcodiotheca gaudichaudii
Callophyllis flabellulata Callophyllis
spp.
Pugetia
firma
Erythrophyllum delesserioides Chondracanthus corymbiferus Gymnogongrus
chiton
Sarcodiotheca gaudichaudii
 Order Rhodymeniales

Order Plocamiales
Botryocladia pseudodichotoma Fauchea laciniata Fryeella gardneri Gastroclonium subarticulatum Rhodymenia californica Rhodymenia pacifica Plocamium pacificum
Botryocladia
pseudodichotoma
Fauchea laciniata Fryeella
gardneri
Gastroclonium subarticulatum Rhodymenia californica Rhodymenia pacifica Plocamium pacificum
 Order Halymeniales  Order Ceramiales
Prionitis lanceolata
Cryptopleura ruprechtiana Cryptopleura spp. Microcladia coulteri filamentous reds
Prionitis lanceolata  Cryptopleura ruprechtiana
Cryptopleura
spp.
Microcladia coulteri filamentous
reds

  Order Gelidiales
  Order Corallinales
Gelidium robustum

Bossiella spp.
Calliarthron spp. encrusting corallines
Gelidium
robustum
Bossiella
spp.
Calliarthron
spp.
encrusting corallines























Chondracanthus corymbifera
Chondracanthus corymbiferus  (Kützing) Guiry 
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Gigartinaceae

Broad unbranched blades in clumps; younger blades smooth & iridescent, older blades large & fleshy with course papillae (reproductive cystocarps). 

Abundant; on rocks; one of the dominant space occupants, especially in shallower areas of kelp forest.

Geogr. Range: Washington State to Baja
Synonyms: Gigartina corymbifera
Similar species:

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Callophyllis flabellulata Callophyllis flabellulata  Harvey
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Kallymeniaceae

Thalli small and delicately branched,  4-8 cm; main axis 5x broader than higher order branches; tips only a few mm wide. 

Moderately common, but inconspicuous due to size; on rocks throughout kelp forest.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species:

Image: Bossiella (lower cntr.), Rhodymenia pacifica (rt. side), Balanophyllia (upper rt.)

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Callophyllis sp. Callophyllis
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Kallymeniaceae

Clusters of thin, smooth blades lacking midrib or veins; main axis broader, with successive orders of branching become increasingly narrower.

Common on rocks throughout kelp forest, especially in shallower areas.

Geogr. Range:
Synonyms:
Similar species: Callophyllis violacea is one of the more common local species of Callophyllis., but this is a large genus with numerous species.

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Pugetia firma Pugetia firma  Kylin
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Kallymeniaceae

Single disc-like blade 4-10 cm diameter growing around central discoid holdfast; bluish-red, slippery, tough.

Moderately common, on rocks.

Geogr. Range: British Columbia to Baja
Synonyms: Callophyllis firma
Similar species:

Image: Balanophyllia (lower cntr. & rt.)


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Erythrophyllum delesserioides Erythrophyllum delesserioides  J.Agardh
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Kallymeniaceae

Lance-shaped blades 30-50 cm long with obvious midrib & forked veins; dark red.  Thalli are annual; begin to grow in mid-winter, reach maximum length in early summer; lateral margins erode thereafter with remaining portion growing many papillae.  

Locally common, but infrequently encountered in kelp forests; on rocks in very wave-exposed sites subject to heavy surf; low intertidal zone to subtidal.

Geogr. Range: Alaska to San Luis Obispo (central Calif.)
Synonyms:
Similar species:

Image: foreground covered with Rhodymenia pacifica.


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Gymnogongrus chiton Gymnogongrus chiton  (Howe) P.C. Silva & DeCew
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Phyllophoraceae

Erect stiff branches 8-15 cm tall, dichotomous branches 4-6 mm wide at tip; tips robust & somewhat thick; dark wine-red.

Moderately common; on rocks at shallower depths within kelp forest, often mixed with geniculate corallines.

Geogr. Range: British Columbia to Baja
Synonyms: Gymnogongrus platyphyllus
Similar species: thallus of Rhodymenia pacifica grows flat rather than in a more erect rosette and its branch tips are much thinner than Gymnogongrus.

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Sarcodiotheca gaudichaudii Sarcodiotheca gaudichaudii  (Montagne) P.W. Gabrielson
Phylum Rhodophyta, Class Florideophyceae, Order Gigartinales, Family Solieriaceae

Thallus 10-40 cm tall, cylindrical; cylindrical side branches off main axis are lumpy & taper to a point. Color varies from dark red to pale red.

Common on rocks, especially in shallow areas.

Geogr. Range: British Columbia to Baja
Synonyms: Neoagardhiella baileyi

Similar species:


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Plocamium pacifiicum Plocamium pacificum  Kylin
Phylum Rhodophyta, Class Florideophyceae, Order Plocamiales, Family Plocamiaceae

Thallus 4-25 cm tall with several erect axes; flattened cylinder in cross section; delicate plume-like side branches curve to a pointed tip; main axis has a zig-zag appearance; shiny red.

Common, on rocks throughout kelp forest. 

Geogr. Range: British Columbia to Baja
Synonyms: Plocamium cartilagineum
Similar species: Microcladia coulteri has a similar appearance, but is usually epiphytic, smaller, and its main axis is straighter, rather than zig-zag.

Image: Henricia (lower rt. cntr.), Calliostoma annulatum (bottom rt.), Hippoporina insculpta (top rt.)


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Rhodymenia pacifica Rhodymenia pacifica Kylin
Phylum Rhodophyta, Class Florideophyceae, Order Rhodymeniales, Family Rhodymeniaceae

Flat thalli 3-13 cm long, dichotomously branched; tips usually rounded, 3-10 mm wide & rather thin. Branch tips broader than Rhodymenia californica (in top & upper right of photo).

Very abundant, on rocks. One of the dominant space occupants along with Chondracanthus corymbiferus & geniculate corallines. Older thalli usually encrusted heavily with bryozoans, spirorbid tube worms, and hydroids.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: Rhodymenia californica is narrower. Fryeella gardneri has a similar shape, but is iridescent purple & has arching internal septa in its blades.

Image:  Rhodymenia californica (across top)

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Rhodymenia californica Rhodymenia californica  Kylin
Phylum Rhodophyta, Class Florideophyceae, 

Flat thalli 3-7 cm long, dichotomously branched; tips rounded, pointed or irregular 1.5-3 mm wide. 

Very abundant, on rocks mingled with Rhodymenia pacifica. Older thalli usually encrusted heavily with bryozoans, spirorbid tube worms, and hydroids.

Geogr. Range: British Columbia to Mexico
Synonyms:
Similar species: Rhodymenia pacifica has much broader branch tips. Fryeella gardneri is broader and iridescent purple with arching internal septa in its blades.

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Fryeella gardneri Fryeella gardneri  (Setchell) Kylin
Phylum Rhodophyta, Class Florideophyceae, Order Rhodymeniales, Family Rhodymeniaceae

Thallus to 16 cm tall; irregularly dichotomous branches with tips 8-10 mm wide with rounded tips; iridescent  purple; arching internal septa are visible when thallus held up to light.

Common but seasonal (rare in winter), on rocks throughout kelp forest.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: Rhodymenia pacifica and Rhodymenia californica are similar in shape, but neither is iridescent purple and both lack arching internal septa.

Image: Acanthancora (across top), sponge Haliclona? (top left)

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Botryolcladia pseudodichotoma Botryocladia pseudodichotoma  (Farlow) Kylin
Phylum Rhodophyta, Class Florideophyceae, Order Rhodymeniales, Family Rhodymeniaceae

Thallus 10-15 cm tall; several cylindrical axes with fingerlike bladders 1-3 cm long filled with mucoid polysaccharides; dark red.

Common, on rocks throughout kelp forest, but especially in intermediate & shallower depths.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: one of the most distinctive of local red algae.

Image: Rhodymenia californica (bottom cntr.), Callophyllis sp. (center)

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Fauchea laciniata Fauchea laciniata  J. Agardh
Phylum Rhodophyta,Class Florideophyceae, Order Rhodymeniales, Family Faucheaceae

Thalli 3-12 cm in clusters forming a flattened rosette around discoid holdfast; deep red with iridescent blue; blade often with obvious bumps (reproductive cystocarps). 

Moderately common, on low-lying rocks.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: Fryeella gardneri is also iridescent but is more purple; its thallus is smooth with arching internal septa that are lacking in Fauchea.

Image: Derbesia (giant unicellular green alga) top center.

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Gastroclonium subarticulatum Gastroclonium subarticulatum  (Turner) Kützing
Phylum Rhodophyta, Class Florideophyceae, Order Rhodymeniales, Family Champiaceae

Thalli 10-26 cm tall, erect, cylindrical in cross section to 2.5 mm diameter; branching irregular to dichotomous; apices of branches hollow with transverse septa; dark red  to greenish-brown depending on location & time of year.

Common in relatively sheltered sites, on rocks in shallow subtidal & especially low to mid-intertidal; ~seasonal, regrowing from persistent basal portions after winter erosion.

Geogr. Range: British Columbia to Baja
Synonyms: Gastroclonium coulteri
Similar species:

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Prionitis lanceolata Prionitis lanceolata  (Harvey) Harvey
Phylum Rhodophyta, Class Florideophyceae, Order Halymeniales, Family Halymeniaceae

Thallus of 1-2 flattened stipes 20-30 cm tall from discoid holdfast; branches dichotomous 2-5 mm wide with flattened lanceolate lateral proliferations. Branch widths remain ~constant throughout length; relatively stiff; dark red with main axes appearing nearly black in low light.

Common, on rocks in shallower portions of kelp forest; also abundant in mid to low-intertidal zone where plants are somewhat more bushy.

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species:

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Cryptopleura ruprechtiana Cryptopleura ruprechtiana  (J.Agardh) Kylin
Phylum Rhodophyta, Class Florideophyceae, Order Ceramiales, Family Ceramiaceae

Thallus 10-50 cm growing from ribbon-like base; blades thin & mildly iridescent; branches elongate, fan-shaped, deep rose to brownish-red with lateral proliferations & ruffles; vein-like midribs visible near base of blades. 

Common, on rocks or growing epiphytically on geniculate corallines throughout kelp forests in areas with stronger water motion.

Geogr. Range: British Columbia to Baja
Synonyms: Botryoglossum farlowianum var. farlowianum
Similar species:  Cryptopleura spp. require microscopic examination of arrangement of reproductive tetrasporangia to distinguish unambiguously.

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Cryptopleura sp. Cryptopleura spp.
Phylum Rhodophyta, Class Florideophyceae, Order Ceramiales, Family Ceramiaceae

Thallus 5-50 cm tall; blades branched with fan-shaped tips, midribs of visible veins begin at base of blades and divide upward, becoming microscopic.  Margin of blades vary from smooth to having small proliferations or ruffles. Brownish-red to rose red with greenish tints.

Common, on rocks in low intertidal and subtidal habitats.

Geogr. Range:
Synonyms:
Similar species: Cryptopleura spp. require microscopic examination of arrangement of reproductive tetrasporangia to distinguish unambiguously.

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Microcladia coulteri Microcladia coulteri  Harvey
Phylum Rhodophyta, Class Florideophyceae, 

Thallus planar 35-40 cm tall (usually smaller); main axis with many highly branched delicate laterals. 

Common, epiphytic on larger red algae such as blades of Chondracanthus corymbiferus (as in photo).

Geogr. Range: British Columbia to Baja
Synonyms:
Similar species: Plocamium pacificum has zig-zag main axis while that of Microcladia is ~straight.

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filamentous reds filamentous reds
Phylum Rhodophyta, Class Florideophyceae, Order Ceramiales

Turf of small filament-like thalli to several cm tall; a large number of species have this morphology. Non-descript to unaided eye; only reveal their delicate beauty & diverse morphology under the microscope.

Common, but patchy; often in recently disturbed locations or low-lying rocks where scour by shifting sediment occurs frequently.

Geogr. Range:
Synonyms:
Similar species: require microscopic examination to identify.

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Gelidium robustum Gelidium robustum (Gardner) Hollenberg & Abbott
Phylum Rhodophyta, Class Florideophyceae, Order Gelidiales, Family Gelidiaceae

Thallus to 40 cm tall, flattened cylinder in cross section; side branches arise from distinct main axis with ultimate branchlets usually 1 mm wide; rose to dark red.

Common, low intertidal zone to subtidal; protected outer coast.


Geogr. Range:
northern California to northern Baja
Synonyms:
Similar species:

Image:
Rhodymenia pacifica (down rt side), hydroid Aglaophenia (lower rt).

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Bossiella sp. Bossiella spp.
Phylum Rhodophyta, Class Florideophyceae, Order Corallinales, Family Corallinaceae

Erect, pink jointed thalli to 12 cm long, from crustose base; impregnated with CaCO3; intergenicula (areas between joints) flattened throughout with blunt wings, >2 mm long at branch tips, 4+ conceptacles (bumps with reproductive structures) on faces (but not lateral margins) of fertile intergenicula.

Abundant on rocks in areas with high water motion.

Geogr. Range:
Synonyms:
Similar species: intergenicula of Calliarthron spp. shaped like wing nuts with wings at an angle to main axis; its conceptacles are on lateral margins as well as faces of intergenicula.

Image: Balanophyllia elegans (scattered)

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Calliarthron sp. Calliarthron spp.
Phylum Rhodophyta, Class Florideophyceae, Order Corallinales, Family Corallinaceae

Erect, pink jointed thalli 20-30 cm long, from crustose base; impregnated with CaCO3; basal intergenicula (areas between joints) rounded in cross section & longer; upper intergenicula flattened with wings angled 45-60° from main axis; conceptacles (bumps with reproductive structures) on lateral margins of fertile intergenicula (on some faces of lower intergenicula).

Abundant, on rocks with strong water motion.

Geogr. Range:
Synonyms:
Similar species: intergenicula of Bossiella not as wing nut-shaped as Calliarthron; conceptacles located on faces, not margins of fertile intergenicula.

Image: specimen in photo is rather eroded; angle of wings can be seen just above the center of the image

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encrusting corallines encrusting corallines
Phylum Rhodophyta, Class Florideophyceae, Order Corallinales, Family

Pink, calcified crusts covering rocks. Microscopic examination of reproductive structures usually needed to identify.

Very abundant, on rocks everywhere.

Geogr. Range:
Synonyms:
Similar species: common genera include Lithothamnion, Lithophyllum, Pseudolithophyllum

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Page created by J.M. Watanabe
All images copyright James Watanabe unless otherwise indicated
Contact:  watanabe_at_stanford_dot_edu                                                                                                                                   Last  update: 24 August 2010