Acropora, Oken, 1815

Sola, Erwan, Silva, Isabel Marques da & Glassom, David, 2015, An annotated and illustrated checklist of species of the coral genus Acropora (Cnidaria: Scleractinia) from Vamizi Island, Mozambique, African Invertebrates 56 (3), pp. 807-807 : 823

Acropora gemmifera (Brook, 1892)

Fig. 13

Colony growth form: Digitate or corymbose with thick tapering; almost conical branches; incipient axial corallites occur near base of branches.

Axial corallites: Outer diameter 2.7–3.5 mm; inner diameter 1.0– 1.1 mm; short but conspicuous; thick walled with a small opening; septa are reduced and smooth edged but clearly present in two cycles.

Radial corallites: Dimorphic, usually in rows; larger ones are tubular with dimidiate opening (or completely dimidiate) and may become slightly nariform at branch extremity; typically, these increase in size down the branch and have thickened lower wall; smaller radials are sub-immersed; septal development is rudimentary and dentate.

Coenosteum: Irregular costae on corallites and coarsely reticulate with scattered spinules in intercorallite area.

Remarks: A. gemmifera and other species of the A. humilis group can be difficult to distinguish as noted in the literature. In Wallace and Wolstenholme (1998), A. gemmifera is “ distinguished by the consistent presence of immersed as well as longer radial corallites throughout a branch in A. gemmifera ”. We have made the distinction on this basis and because the size of radial corallites clearly increases down the branch ( Veron & Wallace 1984).

Figures

Fig. 13. Acropora gemmifera. Specimen number: (A, F, G) VAM22; (B–E) VAM2. (A) live colony; (B) branch tip detail; (C, D) branch fragment; (E, F) axial corallite; (G) radial corallites.