Tubastraea coccinea Lesson, 1829
Tubastraea coccinea is an azooxanthellate coral (lacking symbiotic algae), which grows in colonies consisting of clumps of calcareous cups, projecting from a spongy calcareous base. The corallite (calcareous wall around a single polyp) is cylindrical, up to 11 mm in diameter, and may be flush with the colony skeleton (coenosteum) or project up to 4 cm above it. The synapticulotheca (wall of the corallite) is porous and lacks a covering layer (epitheca). The corallite skeleton is white, with poorly defined ribs. The interior of the corallite is partly divided by septa, projecting into the body cavity - there are four kinds of septa, of varying width (S1>S2 >S3>S4), which are arranged in cycles around the opening of the corallite. There are 48 septa. The septa do not protrude on the exterior of the corallite. There is a prominent columella- a projection of the skeleton in the center of the corallite. The body of the polyp itself is deep red or orange, while the tentacles are yellow to bright orange (description from: Kaplan 1988; Cairns 2000; Figueira de Paula and Creed 2004).
The colonies of T. coccinea can vary greatly in arrangement, probably as a result of their environment. They can be cerioid - composed of corallites united directly to one another by fused walls, with corallites that are juxtaposed; plocoid - composed of more or less cylindrical corallites having distinct walls, and the coenosteum separates corallites within a colony; or phaceloid - composed of laterally free corallites forming tufts, and the corallites are separated by void space. In shallow waters, subject to waves and currents, colonies are usually cerioid to plocoid and tightly arranged, but in deeper calmer waters they are more likely to be phaceloid and loosely arranged, with widely projecting corallites. Colonies tend to form spherical or mound-shaped clumps, up to 14 cm in diameter, and strongly attached to the substrate (description from: Cairns 2000; Figueira de Paula and Creed 2004).
Two morphotypes of T. coccinea were observed on an oil platform in the Gulf of Mexico, a dark-orange red form with corallites not projecting far above the colony surface (plocoid, 'low' morphotype), and a yellow form with corallites projecting and loosely arranged (phaceloid, 'high' morphotype). Both forms (examined by Stephen Carins) had skeletal morphology corresponding to T. coccinea, but they show differences in distribution, substrate preference, reproductive timing, and could represent cryptic species (Shearer 2011).
Tubastraea micranthus (Black Sun Coral) has a skeleton resembling that of T. coccinea, but is green-black in color. So far, outside its native Indo-Pacific, it is known from one oil platform off Louisiana (Sammarco et al. 2010; Creed et al. 2016).
Tubastraea tagusensis was described from the Galapagos Islands. It is known from a few widely scattered locations in the Indo-Pacific been introduced in Brazil (Figueira de Paula and Creed 2004; Creed et al. 2016).