Corallum arborescent, closely branched. Branches long, stout terete, mostly arcuate, very slightly tapering. Stem 18.5 mm across near base. A branch is 12.5 mm across at base, 10 mm at middle, 6 mm just below apex; 11.5 cm long. Surface rough because of inequality of radials. Base of stem and branches smooth because of obsolescence of corallites.
Axial corallite cylindrical 2-3 mm diameter, 1.5 mm exsert or conical (very slightly exsert). Calice relatively small. Wall moderately thick, closely costulate, finely echinulate at base; porous; edge rounded or slightly so. Radials not very crowded; various sizes and positions. Most prominent ones cylindrical with rounded calice, erect, 1.5 mm across, 4 mm high when with 1 or 2 small buds. Nonproliferous tall radials up to 3 mm high, 1.3 mm diameter, almost erect or appressed; base wider than apex; calice oval, facing horizontally upward, mostly because of upward bending of lower wall; wall thick, abundantly echinulate, seriate or nonseriate. Towards proximal regions, these nonproliferous corallites become lower, distinctly conical with calicinal opening on upper wall, so apex of cone projects to lower side. Interspersed among prominent radials are lower, smaller ones (diameter below 1 mm) of same shape, mostly appressed tubular with calices facing in all directions, even downward; their wall thin; none actually immersed or subimmersed. Extensive areas towards bases of stem and branches are bare of corallites.
Septa in axial corallite in 2 distinct cycles, the primaries reaching half radius points; directives not very distinguishable except at bottom where they are widened considerably. In distal radials, primaries narrow but complete, directives, especially lower, distinguishable; number of secondaries usually absent.
Intercalicinal areas dense; in some reticulation obscured by abundant uniform spines similar to those on calicinal wall. In areas where spines not so crowded, reticulation quite distinct, the meshes polygonal or elongated running usually longitudinally, slightly wider than threads.
The close affinity of this coral to A. formosa is discernible except for the less prominent septa and the position of the radials.
Its closeness to A. robusta is rather obvious at first sight. However the present species appears very rugged because of the various positions and height assumed by the radial corallites which become appressed and thicker walled towards the basal regions of the branches.
