The hexapodid genus Paeduma Rathbun, 1897 (replacement name for Amorphopus Bell, 1859) was established without figure for a species from an unknown locality, P. cylindraceum (Bell, 1859) (described as Amorphopus cylindraceus Bell, 1859). Paeduma cylindraceum was never reported ever since, and the holotype was considered lost. The examination of the holotype of Paeduma cylindraceum permits to know its provenance (the Galápagos Islands or alternatively somewhere on American Pacific coast) and the exact nature of the supposedly rudimentary fifth ambulatory leg (P5) described by Bell (1859). The “rudiment” is in fact the external and exposed portion of the apodeme of P4 and not an “aborted” pereopod. The two other species subsequently attributed to Paeduma are referred to Hexalaughlia n. gen. A new diagnosis for Paeduma is provided, and the status of the extant and fossil Stevea Manning & Holthuis, 1981 is re-considered. Evaluation of Paeduma has prompted some new views on the family Hexapodidae, and the presence for the first time of two genera of the family in the Americas, Paeduma and Stevea.
Crustacea, Decapoda, Brachyura, Hexapodidae, Amorphopus, Paeduma, Stevea, Hexalaughlia n. gen., vestigial coxa, male gonopore, new genus.