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Raninoida is a taxonomic section of the crabs, containing a single superfamily, Raninoidea. This group of crabs is unlike most, with the abdomen not being folded under the thorax . It comprises 46 extant species, and nearly 200 species known only from fossils .
Raninidae is a family of unusual crabs, sometimes known as "frog crabs", on account of their frog-like appearance.They are taken by most scientists to be quite primitive among the true crabs.
In the waters in and around New Zealand, 77 living species of crabs (and 10 species of crab-like Anomura) have been recorded, along with a further 24 species of fossil crabs (marked with an obelisk). [1]
The group consisting of Raninoida and Cyclodorippoida split off next, during the Jurassic period. The remaining clade Eubrachyura then divided during the Cretaceous period into Heterotremata and Thoracotremata. A summary of the high-level internal relationships within Brachyura can be shown in the cladogram below: [44] [43]
Morphological and molecular analyses do not reveal a monophyletic Podotremata, but rather that it is paraphyletic, and so the most recent classifications divide "Podotremata" into three sections: Dromiacea, Cyclodorippoidea and Raninoida. [1] [2] This group contains the following superfamilies (with their current sections indicated in parentheses):
Thoracotremata is the sister group to Heterotremata 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".
Raninoida. Cyclodorippoida. Eubrachyura: Heterotremata. Thoracotremata. References This page was last edited on 9 December 2024, at 02:18 (UTC). Text is ...
The Grapsoidea are a superfamily of crabs; they are well known and contain many taxa which are terrestrial (land-living), semiterrestrial (taking to the sea only for reproduction), or limnic (living in fresh water).