Systematics or Phylogenetics

Chavan (1937–1938) did the first comprehensive study of Recent and fossil Lucinidae to develop ideas of relationship an phylogeny, which included extensive discussion of the affinities of genera and a geological range chart of recent and fossil genera that outlined his ideas. In 1951, when lucinids with divaricate shell ribbing were reviewed by Chavan, Gilbert &  Van de Poel subsequently classified a new separate subfamily called Divaricelinnae. 1969, Lucinidae was divided into 4 subfamilies namely Lucininae, Myrteinae, Milthinae, and Divaricellinae, but with Fimbriidae as a separate family. Bretsky (1976), working with mostly North American taxa, combined results from a phenetic analysis (Bretsky, 1970) with data from fossils to produce a series of phylogenetic trees for different lucinid lineages. The classification based on these
studies used no suprageneric categories, but divided lucinids into seven broad genera with numerous subgenera. This resulted in major conflicts between shell-based phylogenies and classifications which were thought to stem from homoplasy of shell characters and poor illustrations. However, Chavan's classificationof lucinid genera remains most widely used.  

Molecular results showed major incongruence with previous classifications of Lucinidae based on shell characters. Despite the fact that traditional shell characters have long been and continue to be universally used for the recognition
of genera and species, they have proven to be a poor guide to suprageneric relationships. Major clades - PEGOPHYSEMINAE, LEUCOSPHAERINAE, MYRTEINAE, MONITILORINAE, FIMBRIINAE, CODAKIINAE, and possibly Milthinae  were classified and recognized as subfamilies of Lucinidae.