The genus Boreomysis G.O. Sars, 1869 (Peracarida, Mysida, Mysidae) in western Mexico.

Two species of the genus Boreomysis, B. arctica (Kryer, 1861) and B. californica Ortmann, 1894, were collected in western Mexico. In the eastern Pacific, Boreomysis arctica had previously been recorded from the Bering Sea to southern California. New records in Mexico extend its southernmost distribution limit to 172533 N, off SW Mexico, including samples collected off the west coast of the Baja California Peninsula and the Gulf of California (25 specimens in 12 samples). In the eastern Pacific, B. californica has been reported from Alaska to Peru, with its type locality in the Central Gulf of California. During this study, it was by far the most frequently species collected (343 specimens in 58 samples) off the west coast of the Baja California Peninsula in the Gulf of California, and off SW Mexico (south to 165800 N).

A new deep-sea species of Epimeria Costa in Hope, 1851 (Amphipoda, Amphilochidea, Epimeriidae) from off southwestern Mexico.

A single ovigerous female specimen of a new species of Epimeria Costa in Hope, 1851 was collected from deep sea, off southwestern Mexico, in the eastern Pacific. Epimeria karamani sp. nov., is most similar to females of E. cora J.L. Barnard, 1971, E. pacifica Gurjanova, 1995 and Epimeria morronei Winfield, Ortiz Hendrickx, 2013. However, it differs from these species by: eyes long and slightly kidney-shaped; pleonite 3 strongly carinate, with dorsal tooth produced and acute; urosomite 1 with a wide mid-dorsal notch and a strong, upright blunt tooth; coxa 3 anterior margin slightly truncate and with two processes marginally; coxa 4 ventral margin linear, with facial granules and simple setae; gnathopods palm with distal bifid setae; telson straight medially, distal margin crenulate and with minute setae. The new species described herein increases the number of Epimeria species from the Pacific Ocean to 14, and from the eastern Pacific to three.

Redescription of the rare shrimp Heterocarpus nesisi (Burukovsky, 1986 (Crustacea: Caridea: Pandalidae) rediscovered off western Mexico, with the proposal of a new genus.

A rare species of pandalid shrimp, Heterocarpus nesisi Burukovsky, 1986, is rediscovered in deep water off western Mexico. Previous to this capture, this species was known only from the holotype, a mature male captured at 800 m depth, originally described in the genus Heterocarpus and later transferred to Plesionika. A second, unconfirmed record, was provided in 1989: a female captured at 898 m near the southern tip of the Baja California Peninsula. Heterocarpus nesisi is redescribed and appendages are illustrated. The general morphology of this species makes it difficult to fit within Heterocarpus or Plesionika, and a new genus, Heteronika gen. nov., is proposed to accommodate it. Heteronika nesisi is associated with the lower boundary of the Oxygen Minimum Zone occurring off western Baja California.

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. The new material indicates that P. armiger is widely distributed in the area and more common than previously thought in the eastern Pacific. Samples indicate that P. armiger inhabits water far offshore, where total depth exceeds 1000 m. Due to the lack of discrete samplings in the water column, however, the precise depth interval where P. armiger occurs cannot be defined.

New records of the deep-sea anemone Phelliactis callicyclus Riemann-Zurneck, 1973 (Cnidaria, Actiniaria, Hormathiidae) from the Gulf of California, Mexico.

Specimens of a deep-sea anemone were observed in photographs and video footage taken with the Remotely Operated Vehicle JASON (WHOI Deep Submergence Laboratory) in the Gulf of California, Mexico, in May 2008. Comparison of our material with photographs and description of this species available in literature indicate that the sea anemones filmed during the JASON survey are most likely to represent Phelliactis callicyclus Riemann-Zurneck, 1973. This species has previously been reported from a locality in the Gulf of California near the present record. During the JASON survey, 28 specimens of P. callicyclus were spotted in 27 locations during six dives. The specimens occurred on angular rock outcrops along the escarpments of the transform faults of the Gulf of California, between depths of 993-2543 m and at temperatures ranging from 2.3 to 4.5°C. Based on these new records, Phelliactis callicyclus appears to be widely spread in the Gulf of California.

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. Based on characteristics observed in the new samples and in the type material, N. agassizii Faxon, 1893, is reinstalled as a valid species, and no longer considered a junior of N. gracilipes A. Milne-Edwards, 1881, as proposed by Cardoso & Burukovsky (2014). Along the Pacific coast of Mexico, N. agassizii exhibits a more restricted distribution and it was collected only off the Baja California Peninsula. Previous records of this species in the Gulf of California, where N. faxoni was the only representative of the genus captured during this survey, are considered doubtful.

Habitats and biodiversity of decapod crustaceans in the SE Gulf of California, Mexico.

Samples of benthic macro-fauna were obtained in different habitats along and off the coast of Southern Sinaloa, Gulf of California, Mexico, from 1978 to 1991. Occurrence of species of decapod crustaceans was registered for six habitats, from the interidal to depth of 1200 m. A total of 299 species were collected, belonging to 53 families and including 17 species of Penaeoidea, 45 of Caridea, 6 of Thalassinidea, 5 of Palinura, 1 of Astacidea, 63 of Anomura, and 162 of Brachyura. Number of species varied considerably from one habitat to another. Highest biodiversity was observed in the Bay of Mazatlán, with 121 species, followed by the continental shelf and the rocky interidal (107 species each), the estuarine/coastal lagoons (48 species), the upper slope (18 species) and the sandy beaches (9 species). One species was found to be strictly insular-terrestrial and two are primarily associated with the flotsam. The results of this survey were compared with distribution data available for decapod crustaceans fauna from the SE Gulf of California and the Eastern Tropical Pacific zoogeographic region (ETP). The fauna collected represents 82% of the species cited for the area for coastal and shallow subtidal habitats (to ca. 115 m depth) and 57.6% of deep water (> 200 m) species known to occur in the Gulf of California. Except in two cases, similarity indices (SI) based on the number of species common to any pair of habitats were all very low. Continental shelf and the Bay of Mazatlán have 57 species in common (SI = 0.50), while rocky shore habitat and the Bay of Mazatlán share 27 species (SI = 0.24). Comparative studies of decapod crustaceans communities for the ETP are almost lacking altogether. Available data, however, indicate that biodiversity observed on Southern Sinaloa is so far the highest on record for marine and brackish-water habitants for a given section of this tropical zoogeographic region.