Corallum growing from lateral attachment, caespito-corymbose. Main branches horizontal, irregular, reticulo-coalescent; lower portion flat, palmate at levels of ramification and coalescence; towards periphery cylindrical, 8-9 mm across. Undersurface with immersed corallites all over, intermixed with slightly projecting tubulars; short twigs growing on plane of growth, some lower ones erect. Upper surface of branches evenly covered with immersed corallites which in some areas developed low circumscribing wall. Upper branchlets tapering, mostly in group of 5 or more; 6-7 mm across at base, 1.5-3 cm high. Many groups branchlets grow tall, become prominent and distinct from the rest, branchlets at periphery of groups assuming appearance of those at periphery of colony.

Axial corallite cylindrical, diameter 2 mm or a little over, 1.5-2 mm exsert; wall as thick as calicinal diameter, costulate, slightly porous; edge flat. Septa usually 6, reaching midpoints of calicinal radius, directives indistinguishable; one or 2 small secondaries very occasionally present.

Radial corallites on upper branchlets flat labellate or dimidiate, crowded so walls confluent in some places; around 1.8 mm widest diameter, 2 mm or less high; almost uniform in height so branchlets appear terete; lower lip porous, fragile, projecting almost vertically, apex truncate or rounded, costulate, echinulate in older corallites; septa developed – directives very wide, other primaries narrow; sometimes one or two almost missing; secondaries not always complete thus accentuating asymmetry of septal picture. Immersed corallites on upper surface of branches mostly have directives convergent so calicinal fossa divided into two compartments; rest of septa narrow, incomplete in some. Immersed corallites on lower surface of branches generally with complete 2 cycles but directives nonconvergent.

Intercalicinal areas on branches dense, reticulation not distinct; meshes small, distant. Echinules unevenly distributed, usually in form of narrow plates.

Remark:This coral is quite close to A. prostata, except for its growth habit, the structure of the branches and the unusually broad directives. Brook described as A. prostate a specimen from Fiji which resembles the present one except for the former’s short branchlets (not exceeding 1.8 cm). Brook doubted the identity of his specimen with A. prostata.

Source:Nemenzo F (1967) Systematic studies on Philippine shallow water scleractinians: VI. Suborder Astrocoeniida (Montipora and Acropora). Part I - Text. Nat. Appli. Sci. Bull. 20 (1-2): 1-141.