DEVELOPING A 3D LANDMARK SCHEME FOR GEOMETRIC MORPHOMETRIC ANALYSIS OF THE FAMILY AGARICIIDAE (SCLERACTINIA)

Agariciid corals are unusual in that individual corallites have fewer planes of symmetry than most Scleractinians. This is due to the arrangement of corallites in serial rows, resulting in rectangular corallites, instead of the common hexagonal shape, as well as the tendency of Agariciids to grow in shelf-like plates radiating from a center, causing differences between the proximal and distal ends of the corallites. As a result, 3D landmark schemes used on other groups within the Scleractinia miss important information and are prone to large error when applied to the Agariciids, necessitating the development of a new scheme.

Several approaches were compared. One prospective scheme used a “wedge” consisting of two primary septa and those secondary and tertiary septa between them as the basis for analysis. Another used type one and three landmarks to describe the overall contours of the corallite. A third method combining “wedge” landmarks with landmarks that described overall corallite contour produced the best results when attempting to differentiate species. Future work will use this scheme to address ecological and evolutionary questions regarding the Agariciids.