Type genus. Waldeckia Chevreux, 1906.
Generic composition. Monogeneric.
Diagnosis. Antenna 1 with well developed callynophore in both sexes. Antenna 2 of adult male longer than the body, peduncular articles 4 and 5 enlarged; antenna 2 of female subequal in length to or slightly longer than antenna 1, without peduncular brush setae, geniculate between peduncular articles 3 and 4. Mandibular molar a setose tongue with a vestigial distal triturating patch; palp attached proximally or extremely proximally. Maxilla 1 with 8 / 3 setal-tooth arrangement with broad setal-teeth and ST- 7 slightly displaced from ST- 6. Maxilla 2 without oblique setal row. Gnathopod 1 usually parachelate, occasionally subchelate. Pereopod 4 coxa with very large posteroventral lobe. Uropod 3 rami with plumose setae in both sexes, outer ramus 2 -articulate. Telson deeply cleft.
Remarks. Waldeckia is an enigmatic genus in the Lysianassidae with affinities to the subfamily Tryphosinae, and to a lesser extent the family Uristidae. The well-developed callynophore of antenna 1 in both sexes is comparable to the tryphosines, as is the antenna 2 with brush setae. The 8 / 3 setal-tooth arrangement of maxilla 1 is similar to that of the tryphosines in that it has a broad ST- 6, ST- 7 with ST- 7 slightly displaced from ST- 6, but ST-B – ST-D have moved down the medial face similar to uristids, eurytheneids and some hirondelleids (most obvious in W. australiensis and W. nitens). The mandibular molar is more similar to the setose tongue of uristids, hirondelleids and eurytheneids with a vestigial distal triturating patch. It is, however, unlike the columnar and strongly triturating molar of the tryphosines. Almost uniquely among the lysianassids, gnathopod 1 is always parachelate (except in W. warreen sp. nov. in which it is subchelate), a character only shared with Falklandia reducta (Schellenberg, 1931) in the Tryphosinae. Uropod 3 has plumose setae and the telson is deeply cleft, characteristic of both tryphosines and uristids. Waldeckia shares no characters with lysianassine amphipods.