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Une nouvelle famille de Crabes du Crétacé, et la notion de Podotremata Guinot, 1977 (Crustacea, Decapoda, Brachyura)

Danièle GUINOT & Marcos TAVARES

fr Zoosystema 23 (3) - Pages 507-546

Published on 28 September 2001

A new family of Cretaceous Crabs, and the concept of Podotremata Guinot, 1977 (Crustacea, Decapoda, Brachyura)

The Etyidae n. fam. and the genus Feldmannia n. gen. are described from finely preserved fossil material from the Cretaceous. The family Etyidae n. fam. contains three genera, Etyus, Xanthosia and Feldmannia n. gen., which have often been attributed to the Eubrachyura (Xanthidae, Portunidae). The study of the ventral surface of the cephalothorax shows that the organisation of the thoracic sternum, the presence of a pair of spermathecae at the end of the thoracic sternal sutures 7/8 and the relations between the thoracic sternum and the abdomen conform to the Podotremata. The concept of Podotremata is revised. Phylogenetic relationships within the Brachyura are reviewed, and the synapomorphies for the principal lineages of the Podotremata are suggested, viz. Dromiacea (uropod as a ventral lobe or a dorsal plate); Homoloidea (uropod transformed in a socket); Cymonomidae, Cyclodorippidae, Phyllotymolinidae and Raninoidea (loss of the uropod). If the uropod proves to be completely absent in the Etyidae n. fam. and Dakoticancridae, these exclusively Cretaceous families would have to be added to the latter four. In the Etyidae n. fam., a retaining system of the abdomen is present in both sexes. Feldmannia n. gen. is distinguished from the two other genera of the family, Etyus and Xanthosia, by the weakly curved alignment of the arthrodial cavities of the pereiopods and by the male abdomen. The Archaeobrachyura emend. contain the Cymonomidae, Cyclodorippidae, Phyllotymolinidae and Raninoidea; the Homoloidea are here considered to be a third main podotreme lineage besides the Dromiacea. The identity of the Lower Cretaceous taxon Mithracites vectensis, previously assigned to various families of the Podotremata or Eubrachyura, is here esta-blished with more certainty, with various characters showing that it belongs to the Homoloidea. The genus Secretanella n. gen. is described.

Keywords :

Cretaceous, Podotremata, Etyidae n. fam., Etyus, Xanthosia, Feldmannia n. gen., Secretanella n. gen., Dromiacea, Dynomenidae, Dakoticancridae, Mithracites, Homoloidea, spermatheca, uropod, new family, new genera.

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