NEW PHYLOGENY OF LOBSTERS (CRUSTACEA: DECAPODA) INCLUDING EXTANT AND EXTINCT GENERA SUGGESTS DISTINCT PATTERNS IN DIVERSITY AND EVOLUTION

A phylogenetic analysis based upon adult morphology, including representatives from 44 extinct and 27 extant genera of lobsters, has resulted in a new classification for the group. Every fossil genus with sufficiently preserved members was included in the analysis. According to this analysis, the lobsters are grouped into clades defined upon morphology, but that also have temporal cohesion. Palaeopalaemonida is given separate infraordinal status and is known only from the Paleozoic. Polychelida, a group of clawed lobsters ranging from the Triassic to Recent, is a basal clade, and was most diverse in the Mesozoic. Achelata, comprised of those lobsters lacking claws and currently recognized as the slipper lobsters and spiny lobsters, have Triassic and Jurassic occurrences but radiated much later. Glypheidea is recognized as being comprised of several families that radiated at different times, most notably in the Mesozoic. This group is rare today, represented by only two species. In addition, Glypheidea is notable in embracing both clawed and pseudochelate lobsters. Astacidea is the most recently derived group and includes the clawed lobsters and freshwater crayfish. Crayfish are sister to the marine lobsters. Even this recently derived group is at least Early Jurassic in origin, but the various families radiated and diversified much later. Astacidea is especially abundant and diverse in modern oceans. The phylogeny and the occurrence of characters and their states within it indicates that various morphological attributes, such as claws, flattened body form, and antennal forms, evolved multiple times. This analysis of phylogeny using morphology and including fossil forms reinforces findings from recent genetic work on extant material and also clarifies the relationships among the fossil forms and between the fossil forms and extant groups. Our analysis also clearly indicates that character choice is critical, and that a large range of characters must be incorporated into an analysis, as various characters have importance at different levels in the phylogenetic hypothesis. NSF grant DEB-EF-0531674 funded this research.