Phyllangia americana Milne-Edwards and Haime, 1849
Family: Caryophylliidae
Common names: Hidden Cup Coral
Synonyms: Phyllangia fuegoensis Squires, 1963
Phyllangia americana image
Phyllangia americana  

Species Description: Colonies of the hidden cup coral, Phyllangia americana, form small groups of polyps that encrust hard surfaces (Humann 1993). The corallites are circular with deep central pits. The rims are marked with six primary and six secondary septa. Polyps of P. americana range in color from brown to yellowish brown to reddish brown.

Potentially Misidentified Species: The hidden cup coral is similar in appearance to the speckled cup coral, Rhizosmilia maculata. However, polyps of R. maculata have a distinct speckled pattern and twelve large septa instead of the six seen in P. americana (Humann 1993).

Habitat & Regional Occurrence: The range of P. americana extends from South Carolina (Gleason et al. 2012) to Florida, around the Gulf of Mexico (Cairns 1978), in the Bahamas and throughout the Caribbean (Humann 1993). Polyps encrust the undersides of subtidal rocks, ledges and cave ceilings down to about 50 meters (Cairns 2009). Sponges, algae and other organisms often overgrow the surrounding substrate, making only the individual polyps visible.

Size: P. americana is an ahermatypic coral, meaning that the species is solitary and does not form large reefs like many other stony corals (e.g. Cairns 1978). Individual coral colonies are generally small, with the diameter of polyps measuring about 1.5 cm (Humann 1993).

Abundance: The abundance of P. americana in the IRL remains undocumented. However, average densities of the hidden cup coral on natural and artificial reefs around Tampa Bay, FL have been recorded at approximately 26 colonies per square meter (Rice & Hunter 1992).

Cairns SD. 1978. A checklist of the ahermatypic scleractinia of the Gulf of Mexico, with the description of a new species. Gulf Res. Rep. 6: 9-15.

Cairns SD. 2009. Phylogenetic list of the 711 valid recent azooxanthellate scleractinian species with their junior synonyms and depth ranges. 28 pp. In: Cold-Water Corals: The Biology and Geology of Deep-Sea Coral Habitats. Cambridge University Press, Cambridge. Online:

Gleason DF, Harvey AW & SP Vives. 2012. A guide to the benthic invertebrates and cryptic fishes of Gray’s Reef. Georgia Southern Univ. Online:

Humann P. 1993. Reef Coral Identification: Florida, Caribbean and Bahamas. New World Publications, Inc. Jacksonville, FL. 239 pp.

Rice SA & CL Hunter. 1992. Effects of suspended sediment and burial on scleractinian corals from west central Florida patch reefs. Bull. Mar. Sci. 51: 429-442.

Acrorhagi: Plural of Acrorhagus.

Acrorhagus: Cnidocyte-covered elevation on specialized sweeper tentacles or on the column of anthozoans.

Cnida: An eversible cnidarian organelle that occurs in the cnidocyte.

Cnidae: Plural of cnida.

Cnidocil: A short, stiff, bristle-like cilium that is borne on the cnidocyte and acts as a trigger for the cnida or nematocysts.

Coelenteron: The body cavity and gut of cnidarians and ctenophores; gastrovascular cavity.

Column: The stalk portion of sea anemones.

Hydromedusa: Hydrozoan medusa.

Hydromedusae: Plural of hydromedusa.

Hydrorhiza: Horizontal rootlike stolon of a hydroid colony that grows over the substratum.

Hydrorhizae: Plural of hydrorhiza.

Mesoglea: Connective tissue layer between the epidermis and gastrodermis of cnidarians and ctenophores.

Nematocyst: Stinging cnida of cnidarians.

Ocelli: Plural of ocellus.

Ocellus: A small cluster of photoreceptors; a simple eye.

Oral Disk: Area around the mouth of an anthozoan polyp which bears eight to several hundred hollow tentacles.

Pedal Disk: In some sea anemones, a flattened disc at the aboral end of the column for attachment.

Planula: A cnidarian larva that is elongated and radially symmetrical but with anterior and posterior ends.

Planulae: Plural of planula.

Septa: Plural of septum.

Septum: A double-walled tissue partition in the radial plane of a cnidarian.

Spirocyst: Cnida with a long adhesive thread that functions in capture of prey and in attachment to a substratum.

Tentacle: Evagination of the body wall surrounding the mouth which aids in the capture and ingestion of food.

Zooxanthella: A golden-brown alga, usually a dinoflagellate, that is symbiotic with various marine animals, especially cnidarians.

Zooxanthellae: Plural of zooxanthella.

Phyllangia americana image
Phyllangia americana