Corallum flabello-meanroid, growing from broad base; 8.6 x 6 cm across. Valley continuous, consisting of one along its long axis and several side branches issuing from it; up to 3.5 cm wide, wider still at the ends; about 3.5 cm deep. Wall very thin at edge but greatly thickened just below it by large endothecal vesicles.

Septa very coarse, large, distant, unequally exsert thus giving coral its jagged appearance. Usual distance between septa at mural rim 4 mm. Primaries up to 10 mm wide, exsert up to 10 mm, mural rim raised appreciably at both sides of primary septum, the elevation carrying the smaller septa along; edge entire, thickened and slightly toothed at bottom of fossa; those from opposite sides of valley almost meeting or overlapping, slightly deflected. Smaller septa not reaching bottom of fossa, 2-4 intercalated between 2 adjacent primaries. Large vesicles very visible inside interseptal loculi. Septal surface smooth, except for some fine granules close to edge. Columella absent.

Costae not prominent, except just outside rim, obscured on the rest of outer surface by blister-like exothecal vesicles; may reappear as very thin lamellae towards base.

Remarks: This species should resemble to a certain extent Euphyllia cultrifera Dana which Matthai (1928) has included under Plerogyra sinuosa. It differs from the older species by its very exsert, broad septa set farther apart from each other.

Source: Nemenzo F (1960) Systematic studies on Philippine shallow water scleractinians: III. Suborder Caryophylliida. Nat. Appli. Sci. Bull. 17: 207-213. 2 pls.