See text Heterotremata is a clade of crabs, comprising those crabs in which the genital openings are on the sternum in females, but on the legs in males.

[1] Heterotremata is the sister group to Thoracotremata within the clade Eubrachyura, having diverged during the Cretaceous period.

Eubrachyura itself is a subset of the larger clade Brachyura, which consists of all "true crabs".

A summary of the high-level internal relationships within Brachyura can be shown in the cladogram below: [2][3] Dromiacea Raninoida Cyclodorippoida Heterotremata Thoracotremata The internal relationships within Heterotremata are less certain, with many of the superfamilies found to be invalid.

The proposed cladogram below is from analysis by Tsang et al, 2014:[2] Potamonautidae Potamidae Gecarcinucidae Pseudothelphusidae (New World freshwater crabs) Trichodactylidae (freshwater crabs) Orithyiidae Belliidae Chasmocarcinidae Retroplumidae Ethusidae Dorippidae Leucosiidae Inachidae Epialtidae (paraphyletic) Majidae / Mithracidae Corystidae Euryplacidae Matutidae Calappidae Parthenopidae Cancridae Carpiliidae Aethridae Pseudocarcinus of Menippidae Menippe of Menippidae Polybiidae Portunidae Tanaochelidae Galenidae Pilumnidae Mathildellidae Eriphiidae Oziidae Vultocinidae Trapeziidae Goneplacidae Scalopidiidae Xanthidae (paraphyletic) Panopeidae However, recent studies have found the following superfamilies and families to not be monophyletic, but rather paraphyletic or polyphyletic:[2][3]