Deep-sea Ophiuroidea (Echinodermata) collected during the TALUD cruises in western Mexico.

Deep-sea ophiuroids from western Mexico have been documented since 1899, but mostly by non-Mexican expeditions. TALUD is a Mexican project designed to study the deep-sea fauna from Mexico. As part of it, the present contribution provides for the first time detailed information about the taxonomy and distribution, as well as images, of deep-sea ophiuroids from western Mexico, representing a useful taxonomic identification tool for Ophiuroidea from the eastern Pacific. A total of 38 species of ophiuroid (35 identified at species level, one at genus level, and two as confer) were collected from 83 stations located at 123‒2,309 m depth. At a regional scale, several new species records are presented: six for western Baja California, five for western Baja California Sur, two for the Gulf of California, four for Jalisco, 14 for Colima, and five for Guerrero. Geographic (six) and bathymetric (seven) distribution ranges of species are extended. An updated list of deep-sea ophiuroids (61 species) from western Mexico is provided together with an identification key to species collected during this survey. In addition, nine records of deep-sea ophiuroids for the Mexican Pacific are unproven, doubtful or invalid. We corroborated the presence of Ophiacantha eurypoma and Ophiacantha pacifica in the study area and added Amphiura gymnogastra as the first record for Mexico. We propose to transfer Ophiacantha phragma to Ophiolimna on account of it having both granules and spines on the dorsal disc and striated arm plates. TALUD cruises collected 57 % of the total deep-sea species known to occur off Mexico, making it the most important survey of deep-sea Ophiuroidea carried out in western Mexico to date.

On a small collection of mysids (Crustacea, Peracarida, Mysida) from the southern Gulf of California, western Mexico, with the description of new species of Mysidium and Cubanomysis.

Four species of Mysida were collected in the southwestern Gulf of California, Mexico, including a new species of Mysidium (Mysidium), Metamysidopsis frankfiersi, Siriella gracilis, and a new species of Cubanomysis. The new species of Mysidium is the eleventh species in this genus, with species represented along both coasts of the Americas. It is the third species occurring in the eastern Pacific. The new species of Cubanomysis is the third species in this genus; the other two occur in California and in the western Atlantic.

The lophogastrids (Crustacea: Peracarida: Lophogastrida) of Indonesia and its adjacent waters. An updated checklist.

The zoogeographic distribution of lophogastrid species (Crustacea: Peracarida: Lophogastrida) occurring in the Indonesian waters is presented. For each species, data on general distribution, bathymetric ranges, habitat and localities reported on published data are provided. A total of 20 lophogastrid species belonging to three families and seven genera occur in Indonesian waters (about 38% of all known lophogastrids species worldwide), a number greater than other areas of Southeast Asia. Also, based on current information, the number of species or species richness is greater than other regions, such as Madagascar, North Pacific off Japan, Mediterranean, Canary Island, northern mid-Atlantic ridge, Iberian Peninsula, Mexico, and Angola Basin (SE Atlantic). Most of the Indonesian species are distributed worldwide, but one species, Lophogaster inermis appears to be endemic to Indonesia. Previous listings of Paralophogaster intermedius occurring in Southeast Asian waters is not verified in any collections, and has therefore been removed from our updated list.

Biflustra irregulata (Cheilostomata: Membraniporidae): A tsunami debris rafted Indo-Pacific bryozoan found in the eastern Pacific Ocean.

Previous studies documented colonies of the cheilostome bryozoan Biflustra irregulata rafting across the Pacific Ocean on debris from the 2011 Great East Japan megathrust earthquake and resulting tsunami. They arrived in the eastern Pacific on floating non-biodegradable tsunami debris from 2014 to 2016. Based on a newly discovered occurrence of this species off the west coast of Mexico, we report that this species has successfully expanded its range from the Indo-Pacific to the northeast Pacific following this dispersal event. Colonies were found encrusting barnacles on spiny lobsters from the southeastern Gulf of California.

Redescription of Paguristes aztatlanensis Glassell, 1937 and description of a new species of the genus Paguristes Dana, 1851 (Anomura, Paguroidea, Diogenidae) from western Mexico.

A redescription of Paguristes aztatlanensis Glassell, 1937 is presented together with the description of Paguristes turkayi n. sp. from the Mexican Pacific. Paguristes turkayi n. sp. is close to P. digueti and P. sanguinimanus, but can be separated from these two species by the following: P. turkayi features a slender rostrum; the ocular peduncles are proportionally larger relative to the shield in P. turkayi n. sp. than in P. digueti, but proportionally shorter than in P. sanguinimanus; the anterodorsal plates of the carapace are unarmed in Paguristes turkayi n. sp. and P. sanguinimanus (versus armed with small teeth in P. digueti); in P. turkayi n. sp., the palm and carpus of the chelipeds bear fewer but larger spines and tufts of very long setae, while in P. digueti and P. sanguinimanus the chelipeds are armed with many small spines and very short setae.

Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 7. Superfamily Platysceloidea. Family Oxycephalidae.

Twelve species of the family Oxycephalidae were collected during a deep-water survey off western Mexico: four species of Rhabdosoma, three species of Streetsia, two species of Oxycephalus, and one species each of Cranocephalus, Glossocephalus, and Leptocotis. In total, 321 specimens were collected, 114 males and 207 females, in 33 sampling localities in the Gulf of California (28) and off southwestern Mexico (5). Two species dominated in the samples and co-occurred in 17 of the 33 samples containing hyperiids: Oxycephalus clausi (24 localities, 152 specimens) and Rhabdosoma whitei (20 localities, 121 specimens). Considering this study and previous records, a total of 16 of the 18 described species of Oxycephalidae (89%) have been reported from western Mexico. Distribution of this new material off western Mexico is provided together with update data on species occurrence in the eastern Pacific.

Hyperiids (Amphipoda, Hyperiidea) collected during the TALUD cruises in western Mexico. 5. Family Amphithyridae, with the description of a new species of Amphithyropsis Zeidler.

In order to complete the information related to the little studied deep-sea planktonic fauna of western Mexico, samples from a wide depth range (surface to 1550 m depth) were obtained using different gear. Six species and 108 individuals of hyperiid amphipods of the family Amphithyridae were collected at 26 localities, including a new species of Amphithyropsis Zeidler, 2016, which is herein described based on an adult male and a gravid female. Other species include Amphithyrus bispinosus Claus, 1879, the most abundant and frequently collected species (70 specimens at 17 localities), A. muratus Volkov, 1982 (11 specimens at 8 localities), A. sculpturatus Claus, 1879 (14 specimens at 7 localities), Paralycaea gracilis Claus, 1879 (10 specimens from 6 localities), and P. hoylei Stebbing, 1888 (one specimen from one locality). Worldwide and regional distributions are provided for each species.

Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 3. Family Lestrigonidae.

Thirteen species belonging to five genera of pelagic amphipods of the family Lestrigonidae were collected during a deep-water survey off western Mexico: four species of Hyperietta, two species of Hyperioides, five species of Lestrigonus, and one species each of Phronimopsis and Themistella. This represents 93% of all known species of Lestrigonidae world-wide. A total of 1092 specimens were obtained in 40 sampling localities in the Gulf of California (35) and off southwestern Mexico (5). Although sampling methodology was rather heterogeneous, two species, Hyperioides sibaginis and Lestrigonus bengalensis, were particularly abundant (336 and 562 specimens) and frequent (present in 24 and 31 localities) in the samples, representing 82% of the total catch. The southernmost distribution limit of Hyperietta stebbingi is extended to off SW Mexico. Of the 13 species that were collected during this survey, 10 and 8 species co-occurred at two sampling localities in the SE Gulf of California.

Squat lobsters (Crustacea: Decapoda: Anomura: Galatheoidea) from off the northwestern coast of the Baja California Peninusla, Mexico.

Four species of squat lobsters were collected off the northwestern coast of the Baja California Peninsula, Mexico, during an exploratory survey of fishing resources. Janethogalathea californiensis, described from California was previously known from off the west coast of the Baja California Peninsula (two localities) and from the Gulf of California (three localities). Of the three species of Munida collected during the survey, M. tenella is recorded off the west coast of the Baja California Peninsula for the first time. These are the fourth record of M. hispida and the second record of M. quadrispina in western Mexico.

Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 2. Family Eupronoidae.

During deep-water (0-1550m) sampling operations off western Mexico performed between 1989 and 2014, a series of 89 specimens of pelagic amphipods of the family Eupronoidae was obtained, including two genera and four species: Eupronoe armata, E. maculata, E. minuta, and Parapronoe parva. The most abundant species (50% of total number of individuals) and frequently collected species (in 65% of samples with eupronoids) was E. maculata. Worldwide and regional distributions are provided for each species. Notes on previously used names are provided.

Pelagic amphipods (Crustacea: Amphipoda: Hyperiidea) in western Mexico. 6. Superfamily Vibilioidea. Families Paraphronimidae and Vibiliidae.

Ten species belonging to the families Paraphronimidae and Vibiliidae were collected during a deep-water survey off western Mexico: two species of Paraphronima and eight species of Vibilia. This represents about 40% of all known species of these two genera world-wide. A total of 419 males and 607 females were obtained in 39 samples from localities in the Gulf of California (33) and off southwestern Mexico (6). Vibilia armata was by far the most frequently (32 localities) and most abundantly (687 specimens, 67% of the total) collected species, followed by V. longicarpus (231 specimens in nine localities) and P. crassipes (35 specimens in 9 localities). Co-ocurrence of species of Vibilioidea in our samples was very low, with maxima of seven and five species collected in the same sample, once each. Considering previous records, a total of 16 species of Vibilioidea (almost 70% of all known species) have now been reported from western Mexico: two species of Paraphronima and 14 species of Vibilia, including V. australis occasionally reported in the area as its junior synonym, V. wolterecki.

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. So far, this species only has been recorded from seven localities in the North Atlantic and in the North Pacific. A complete description of the only specimen available (a male), including illustrations of all appendages and SEM images of the mandibles, is provided.

Species of Scina Prestandrea, 1833 (Amphipoda, Hyperiidea, Scinidae) from western Mexico with the description of a new species from the Gulf of California.

Only a few previous surveys of the deep-water planktonic fauna have been accomplished off western Mexico, in particular in the Gulf of California. Samples of pelagic amphipods were obtained between surface and as deep as 2394 m using different gear during an extensive survey in this area. Among these samples, nine species of the genus Scina were recognized, including 78 specimens: 27 males and 51 females. The genus Scina inhabits mesopelagic waters at depths over 200 m, a community that remains largely unknown. The material examined includes a new species, the first reported from the Gulf of California, which is described and compared with its closest congeners, S. setigera Wagler, 1926 and S. parasetigera Zeidler, 1990. These three species share the presence of a long bristle on the base of the dactylus of pereopods 5 and 6. Scina sp. nov. differs from these other two species mainly by: 1) the shape and proportions of pereiopods 1-7; 2) the presence of three inner spiniform elements on uropod 1; 3) the insertion of the exopod on distal 1/3 of uropods. Of the remaining species collected during the survey S. borealis was by far the most abundant and widely distributed, followed by S. wolterecki and S. marginata. The other five species, S. curvidactyla, S. nana, S. pacifica, S. setigera, and S. submarginata, were represented by one or two specimens only. Co-occurence of species of Scina in samples was low with a maximum of four species in a single sample, all associated with S. borealis, the most common species. The distribution of Scina species collected during this survey is briefly discussed.

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°51.26'N-116°42.18'W. Although no precise depth range in the water column is known for this species, it has been collected in localities where total depth was at least 1848 m.

Rediscovery of the deep-water species Ypsilocucumis californiae Massin amp; Hendrickx, 2011 (Echinodermata; Holothuroidea; Ypsilothuriidae) in western Mexico.

Four specimens of the sea cucumber Ypsilocucumis californiae Massin Hendrickx, 2011 were obtained during sampling operations off western Mexico. These specimens permit identification of this species as a member of the deep-water holothuroid community off the west coast of the Baja California Peninsula. Previous records correspond to four locations (including the type locality) in the Gulf of California, where eight specimens were collected. SEM ossicles images are provided for the first time and new ecological data associated with the presence of this species are available: temperature, 5.34‒8.38 °C; dissolved oxygen, 0.15‒0.28 ml O2/l and salinity, 34.42‒34.51 ups. The specimens were present in a wide variety of sediments with an organic carbon content of 3.18‒5.20 mg C/g (5.47‒8.95 % organic matter). Density values indicated low abundance of this species in the area (2.63‒3.94 orgs/ha). Records presented here were in a depth range from 540 to 776 m, which corresponds to the lower limit of the Oxygen Minimum Zone of the eastern Pacific. Additional records are provided for the West Atlantic Ypsilocucumis asperrima (Théel, 1886) and a key to the species of Ypsilocucumis is provided.

Species of Gnathophausiidae (Crustacea, Lophogastrida) collected off the west coast of Baja California, Mexico, during the TALUD cruises.

During a survey of the deep-water fauna off western Mexico a large series of specimens of Gnathophausiidae was collected in a benthic sledge operating between 296 and 2136 m. Five species known to occur in the area were collected: Gnathophausia scapularis Ortmann, 1906, G. zoea Willemoes-Suhm, 1873, Neognathophausia gigas (Willemoes-Suhm, 1873), N. ingens (Dohrn, 1870), and Fagegnathophausia gracilis (Willemoes-Suhm, 1875). Additional distribution data are provided for these species in the area. A sixth species, G. childressi Casanova, 1996, previously known only from the type locality, off California, was also collected in three localities. Several external morphological characters in F. gracilis are analyzed according to individual size. The general and regional (off western Mexico) distributions of these six species is analyzed.

Notes on Chasmocarcinus latipes Rathbun, 1898 (Brachyura, Goneplacoidea, Chasmocarcinidae) from the Gulf of California, Mexico.

Brachyuran crabs from the Mexican Pacific and surrounding areas are well known and have been treated in several monographs (e.g., Garth 1958; Hendrickx 1997, 1999). Checklists of species occurring off western Mexico and the eastern tropical Pacific are also available (e.g., Hendrickx 1993, 1995, 2005). In many cases, particularly in species inhabiting the continental shelf or deeper waters, however, there is a significant lack of records due to sampling difficulty and cost.

New records of Synallactes virgulasolida Massin Hendrickx, 2010 (Echinodermata: Holothuroidea) from the eastern Pacific.

Specimens of the sea cucumber Synallactes virgulasolida were obtained during sampling operations off western Mexico. Based on a total of 190 specimens and on additional records available in the Scripps Institution of Oceanography collections, new geographical (southern California to Chile) and bathymetric (712‒1300 m) distributions are provided. SEM photographs of ossicles are provided for the first time for this species. New ecological data associated with the presence of this species are also provided: 4.17‒5.81 °C, 0.15‒0.48 ml O2/l, and in 34.40‒34.48 ups. The species occurs in a wide variety of sediments with an organic carbon content of 17.93‒52.02 mg/g (1.79-5.20 % of organic matter) and is occasionally very dense (up to 170.32 orgs/ha). All Mexican records correspond to a bathymetric fringe located below the Oxygen Minimum Zone, thus indicating that S. virgulasolida is able to tolerate hypoxic conditions.

First zoeal stage of the hermit crab Enallopaguropsis guatemoci (Glassell, 1937) (Crustacea: Anomura: Paguroidea: Paguridea) obtained in the laboratory.

The first larval stage of Enallopaguropsis guatemoci is described in detail and illustrated. The larva is compared with larvae known for other genera of Paguridae except Pagurus. A synthesis of all characters provided herein indicates that first larvae of E. guatemoci can be separated from all known pagurid larvae (except Pagurus) by the combination of the following characters: carapace with long dorsal carina, posterolateral spines absent; abdominal somites 3-5 with pair of moderately long spines; telson narrowly triangular, not forked; spine at antennal protopod as long as endopod.

A new species of the hermit crab genus Areopaguristes Rahayu & McLaughlin (Crustacea, Decapoda, Anomura, Paguroidea, Diogenidae) from the Mexican Pacific.

A new species of hermit crab, Areopaguristes espetacioni, family Diogenidae, is described and illustrated in detail, including the color pattern in live/fresh specimens. This is the fifth species of Areopaguristes reported from the eastern Pacific. Given the morphological similarity between Areopaguristes espetacioni n. sp. and A. tudgei Lemaitre & Felder, 2012, these can be considered sister species. The presence of a long rostrum, the antennal flagella with short setae, chelipeds and ambulatories legs with dense plumose setae, and telson with calcareous teeth on the posterior margin allow to separate Areopaguristes espetacioni n. sp. from all other species in the genus previously described for the region. A key for Areopaguristes species from the eastern tropical Pacific is provided.