Corallum almost globular, living portion encrusting over dead portion, its margin thin, closely adherent to substratum: upper surface with very slight unevenness.

Corallites round, protruding at most 1 mm, mostly less, somewhat evenly distributed, 1 mm or less distant. Calices shallow, up to 4 mm across; “giant” corallites 5- 6 mm across present. Along edge of corallum, many corallites appear ascending in position so costae on lower side prolonged. Wall thin, sometimes incomplete so loculi merge into perithecal vesicles.

Septa alternately wide (reaching columella) or narrow (not reaching columella); usually 12 principal ones and 12 narrow ones. “Giant” corallites have 20 principal septa and as many narrow ones. Septal edges entire, at most very slightly spinulous; large septa have lower portions notched to produce very prominent vertical paliform lobes; septal surface sparingly spinulate, all exsert over calicinal wall. Costae also alternately high and low corresponding to septa, not extending into peritheca.

Columella rather conspicuous, depressed, papillose. Peritheca c.1 mm wide, very vesicular; vesicles are large blisters, some open, most close.

Remarks:The genus Simplastrea is not previously known in the Philippines. It was established by Umbgrove (3) based on a specimen collected from Batavia Bay. Simplastrea leytensis differs from S. vesicularis, the type, by the presence of (a) complete complement of narrow septa not reaching columella, (b) distinct paliform lobes on large septa, and (c) “giant” corallites. No other species of this genus are known.

Source:Nemenzo, F. 1979. Astrocoeniid and faviid reef corals from Central Philippines. Kalikasan, Philipp. J. Biol. 8(1): 37-50.