Acropora Oken 1815

Fig. 4

Colony growth form: Irregularly arborescent, sometimes slightly hispidose; main branches taper and may be very thick, they give-off secondary branches at irregular intervals.

Axial corallites: Outer diameter 2.6–3.3 mm; inner diameter 0.8–0.9 mm; large and thick-walled with small opening; first and second septal cycles are present and well developed.

Radial corallites: Size and shape are variable; usually tubular to rounded tubular or appressed. Primary septa are present, secondary septa are generally absent or incomplete, but well developed in some colonies; radial corallites are numerous and may be arranged in rows or not.

Coenosteum: Densely reticulate with rows of elaborated spinules on and between corallites.