Madrepora prolifera Lamarck, 1816: 281.
Madrepora ethica Duchassaing & Michelotti, 1861: 32.
Type locality. Southern Ocean (holotype MNHN).
MTQ Holdings. Bahamas: G54473–74, G54499–500; Mexico: G48426–28; Venezuela: G51967–70; Virgin Is.: G33176.
Species group: cervicornis.
Description. Colony outline: determinate, predominantly corymbose. Branches: tertiary branching order absent; length: 5 0–100 mm; diameter: 10.0–19.9 mm, axial-dominated, terete; radial crowding: some touching; axial/radial ratio:>1:10. Axial corallites: two synapticular rings; porous; outer diameter 1.4–3.0 mm; inner diameter 0.6–1.5 mm; primary septa to ½ R. Radial corallites: large; two synapticular rings; one size or graded; inner wall developed; shape:
nariform; openings: oval-rounded; primary septa to 1/3 R. Coenosteum: different on and between radials: between radials: reticulo-costate, on radials: costate; spinule shape: single point.
Taxonomic note. This is now recognised as a hybrid. Although this morphological ‘species’ is recognisable based on the skeleton, it has been demonstrated to occur only in the presence of the other two Caribbean species, as an F1 hybrid. The appearance of this hybrid has differing characteristics depending on which species provide the eggs or sperm (Volmer and Palumbi, 2002, Van Oppen et al., 2000). Because the specimens do not belong directly to either of the parent species, we are retaining the separateness of the specimens by listing them here.