PRELIMINARY PHYLOGENETIC ANALYSIS OF THE OXYSTOMATA SENSU LATO (CRUSTACEA: DECAPODA: BRACHYURA): NEW HYPOTHESES ABOUT BRACHYURAN EVOLUTION
Results of the analysis confirm that the Oxystomata is generally valid and embraces the traditionally included Calappidae, Leucosiidae, and Dorippidae as well as the Hepatidae, Parthenopidae sensu lato, and the extinct Necrocarcinidae, Orithopsidae, and Torynommidae. Most Raninidae, traditionally included as oxystomes, were excluded from the group. The extinct Notopocorystes, historically placed within the Raninidae, may not belong to the family; according to our analysis, it is more closely allied with the Calappoidea and Leucosoidea.
The extinct Dakoticancridae and Camarocarcinus were allied with the podotrematous, or primitive, crabs in our analysis. This is the first step toward resolving their phylogenetic placement within the Brachyura.
Most importantly, use of adult dorsal carapace and macroscopic sternal and abdominal characters, often eschewed by neontologists, produces the same general familial arrangement as use of molecular data or pleopod and pereiopod characters commonly used for brachyuran classification and phylogenetics in the neontological literature. In nearly every case, even with incomplete data, fossil and extant congeners were sister taxa in the analysis.