Evolution of the Isognomonidae Woodring, 1925: Phylogenetic and Morphometric Analyses

The Isognomonidae Woodring, 1925 are a pan-tropical family of bivalves that share a system of hinge-ligament strengthening elements called resilifers and a tendency for highly variable shell-shapes. Using an innovative combination of molecular phylogenetics and geometric morphometric shape analysis I directly compare identified genetic groups to the original type-specimen shells. This method was used to produce a robust taxonomic revision where synonymy was tested empirically. Using a novel, vector-based, approach to describe ontogenetic trends within related groups I also evaluated the deeper clades revealed by the phylogenetic analysis for taxonomic utility. The resulting classification designates this monophyletic group as a sub-family, Isognomoninae, which is divided into two genera, Isognomon and Melina, which contain 21-22 species.