Claus, 1879
Cuticle often with surface sculpture. ANT II in males with two apical ART, subequal in length to preceding ART. P I (Amphithyrus bispinosus 2) and II (Amphithyrus bispinosus 3) "twice" chelate: dactyl forming weak subchela with concave distal margin of ART 6, which forms chela with pointed distal process of ART 5. ART II of P VI relatively short, wide, with mid-size semi-circular fissure (Amphithyrus bispinosus 5). UR III with pointed endopodite fused with basipodite (Amphithyrus sculpturatus 3). Telson free, or nearly free.
Five species, 4 in the South Atlantic:
Amphithyrus bispinosus Claus, 1879
Amphithyrus muratus Volkov in Vinogradov, Volkov et Semenova, 1982
Amphithyrus sculpturatus Claus, 1879
Amphithyrus similis Claus, 1879