Two new families, the Alicellidae fam. nov. and the Valettiopsidae fam. nov., are described based on genera traditionally considered as lysianassoid amphipods. The Alicellidae fam. nov. are deep-sea scavengers often associated with thermal vents. They are distinguished from all other amphipods by a combination of characters which includes a callynophore on antenna 1; a broad, serrate left lacinia mobilis (occasionally narrow or vestigial) and a reduced or vestigial right lacinia mobilis (occasionally broad and serrate); simple or subchelate gnathopod 1; an elongate ischium, rectolinear carpus and propodus and a small dactylus on gnathopod 2 (not mitten-shaped); absence of apical robust setae on uropods 1 and 2 and a deeply cleft telson. The family contains 6 genera: Alicella Chevreux, 1899; Apotectonia Barnard & Ingram, 1990; Diatectonia Barnard & Ingram, 1990; Paralicella Chevreux, 1908; Tectovalopsis Barnard & Ingram, 1990; Transtectonia Barnard & Ingram, 1990. The Valettiopsidae fam. nov. are deep-sea scavenging amphipods defined by a combination of characters which includes a callynophore on antenna 1; serrate, curved incisors; a well developed, serrate lacinia mobilis on each mandible, an oblique setal row on the inner plate of maxilla 2, an elongate ischium on gnathopod 2; the absence of robust setae on the apices of uropods 1 and 2 and a deeply cleft telson. The family contains two genera, Valettiopsis Holmes, 1908 and Valettietta Lincoln & Thurston, 1983.
Key words: Crustacea, Amphipoda, new families, taxonomy, Alicellidae, Valettiopsidae