Psalidopus

P. barbouri occurs on continental and insular slopes from Florida, the Bahamas and the Gulf of Mexico, to parts of the Caribbean Sea, perhaps extending as far south as Suriname.[2] P. barbouri lives on steeply sloping soft muddy bottoms, sometimes mixed with sand, at depths of 400–800 m, where the temperature ranges from 6.1 to 10.0 °C (43.0 to 50.0 °F).[2] Adults have a carapace length of 13–32 millimetres (0.51–1.26 in), with the total length of the animal, from the tip of the rostrum to the tip of the tail, being up to 5.5 times longer than the carapace.[2]

P. huxleyi occurs on continental and insular slopes across the Indian Ocean, including the Laccadive Sea, off southern India, the Andaman Sea and the Timor Sea, as well as in the western Pacific Ocean from southern Japan to the Philippines, the Sulu Sea, and the Celebes Sea.[2] P. huxleyi lives on steeply sloping bottoms of various compositions and consistencies, at depths of 500–100 m, where the temperature ranges from 5.9 to 13.6 °C (42.6 to 56.5 °F).[2] The carapace is 10–30 mm (0.39–1.18 in) long.[2]

P. tosaensis lives at greater depth (c. 2800 m) and lower temperature – 1.6 °C (34.9 °F) – than either of the other species of Psalidopus.[3] Although it is geographically closer to P. huxleyi, it appears to be more closely related to P. barbouri.[3]