Euchaetomera plebeja Hansen, 1912 (Mysida; Mysidae) in western Mexico.

The opossum shrimp Euchaetomera plebeja Hansen, 1912 (Mysida; Mysidae) is one of the nine described species currently known in this genus. Until now, it has been considered a rare species, only partly illustrated, known from western Mexico, western Colombia, Peru, and Chile (one specimen in each locality), with a possible additional record off Hawaii. In a recent study, it was recorded abundantly in western Mexico where it was collected in 20 localities, all in the Gulf of California.

Amblyopsoides ohlinii (W.M. Tattersall, 1951) (Peracarida, Mysida, Mysidae) in western Mexico.

The rare pelagic mysid Amblyopsoides ohlinii (W.M. Tattersall, 1951) is reported for the first time off western Mexico and represents the first record in the Pacific Ocean south of Japan and the Kurile-Kamchatka Trench.

Rediscovery of Hansenomysis lucifugus (Faxon, 1893) (Crustacea, Mysida, Petalophthalmidae) in the eastern Pacific.

The deep-water mysid, Hansenomysis lucifugus (Faxon, 1893), previously known only from the type locality off the Galapagos Islands, is rediscovered off western Mexico. A complete description is provided based on this new material. The new records correspond to a series of 15 adult females and increase the known distribution of this species by over 30° of latitude to the north, to 30°51.

Redescription of the mysid Petalophthalmus armiger Willemoes-Suhm, 1875 (Crustacea: Mysida: Petalophthalmidae) and distribution off western Mexico.

Specimens of Petalophthalmus armiger Willemoes-Suhm, 1875, were collected off western Mexico during a deep-water survey. Six males and 32 females were obtained from 18 sampling localities in western Mexico. The species is redescribed in detail, including illustrations of body and appendages, and SEM photographs of the mandibles.

Two species of the deep-water shrimp genus Nematocarcinus A. Milne-Edwards, 1881 (Crustacea, Decapoda, Caridea, Nematocarcinidae) from the Mexican Pacific.

The distribution of two species of the deep-water shrimp genus Nematocarcinus A. Milne-Edwards, 1881, occurring off the west coast of Mexico is analyzed based on a large series of recently collected material. Nematocarcinus faxoni Burukovsky, 2000, is by far the most common and abundant species in the area and it is distributed throughout the central and southern Gulf of California and off the entire Baja California Peninsula south to 17º10'15"N.