Could be either one, you cannot ID them with certainty by pix alone, you really need the skeleton to ID to 100%, just a comment to help clarify these LPS for those interested in further search.
Genus
Cynarina are very seldom free living, usually existing as solitary polyps found attached to the substrate (this has to do with their development from the original settlement of the polyp) with a skeleton consisting of a single circular skeleton with many large septa arranged radially from the central median. They have very large primary septa with lesser secondary septa between each primary. All septa are toothed with prominent paliform lobes near the inner margins. These will become very large solitary specimens as they age, always with a single oral opening.
Genus
Scolymia shares many of the common names that
Cynarina spp. due to it's common appearance of the live specimens, however, skeletal evaluation of specimens will reveal a similar monocentric disc with many raised but obviously less prominent, more densely spaced septa without paliform lobes that generally slope outward to margins that have small spiny teeth. When similarly sized skeletons are compared side by side, the
Scolymia is obviously heavier and denser, and living
Scolymia specimens of similar age tend to often be of larger diameter but more flattened than
Cynarina.
As far as the visual effect of living specimens,
Scolymia tend to be drab olive to brown colors, even the occasional red specimen is more brick-colored, and when expanded, their tissue tends to be more flattened and opaque, conforming to the outward-sloping skeleton as described above than the
Cynarina, which is most often nearly translucent in bright colors and more billowy, following the paliform lobes of the septa. Most often,
Cynarina tissue is so translucent in healthy specimens that the septa may be visualized through the tissue, hence my ID for the
Cynarina based on the photographs.
However, as I always say, all of the morphs of both genera are quite variable, and ID-ing ANY coral from a photograph is most often a crapshoot down to even Genus-level when making a taxonomic evaluation, so take such an id with a grain of proverbial sea salt. Seeing the spiny ridge at the outer margin does make me think of the [iScolymia[/i] though more than the
Cynarina, and there are no large paliform septa in the initial photo...
HTH
