The genus Millepora, commonly known as fire coral, is a calcareous hydrozoan common in tropical seas worldwide. In the western Atlantic, there exist two prominent morphologies that are presently being classified as separate species. Millepora alcicornis is defined by thin nodular branches; Millepora complanata has plate like, smooth blades. However, recent genetic data suggest that the separate morphologies exist because of phenotypic plasticity, and that two genetically isolated clades (including an intermediate form) cannot be distinguished from one another morphologically. Quantitative analysis of coral colony microstructure using thin sections, suggests that it is possible to differentiate between M alcicornis, M complanata, and the intermediate form from each other morphometrically. However, the distinctions aren’t matched by the genetic data, indicating that current described species of Milleporids in the tropical Western Atlantic are not genetically isolated.
Dana Friend, ’09 Centennial, CO
Sponsor: Benjamin Greenstein