Description of three new species of Hyalella Smith, 1874 (Crustacea: Amphipoda) from Southeast Mexico.

Lacandona tropical rainforest is an area with an important hydrological and biological role in Mexico, nevertheless there are few studies about freshwater macrofauna. In this study, we described three new species collected in three different water bodies in the Lacandona tropical rainforest: H. parva from lake Nahá with a minute body size without mucronations on pleonites 1-2, H. montebellensis from lake La Esmeralda with two dorsoposterior carinae on pleonites 1 and 2 (mucronations) and one seta almost at mid-ventral margin of gnathopod 1, and H. lacandonis from lake Península with minute dorsal mucronations on pleonites 1-2 and 2-3 setae on the hind margin of basis of gnathopod 1. Hyalella montebellensis n. sp. and H. lacandonis n. sp. have almost the same number of articles in flagellum of antennae 1-2, both species present four pappose setae on the inner plate of maxilla 1 and telson subquadrate, longer than wide.

Pelagic amphipods (Crustacea, Amphipoda, Hyperiidea) from the southern Gulf of Mexico with notes on the distribution of species.

Background: Studies referring the amphipod diversity have been mainly focused on the benthic environment. This study aimed to analye the epipelagic amphipod fauna composition in a sector of the southern Gulf of Mexico (GoM). Previous records in the Gulf mainly comprised the oceanic province; our dataset included both oceanic and neritic zones, off several fluvial and lagoon systems. The biological material comprised 485 data records and a total abundance of 3,802 individuals. New information: Surveys were conducted at 21 sampling stations around the Veracruz Reef System National Marine Park, a marine protected area in the southern GoM. As a result of this research, we found 16 families, 34 genera and 78 species belonging to the suborder Hyperiidea. Our records include species from the oceanic province (up to 1,200 m depth), such as those from the genus Scinia, members of the infraorder Physosomata. In addition, Lycaeopsiszamboangae were found off the Alvarado Lagoon. Information on the habitat of 78 amphipod species (neritic, oceanic) is provided. The dataset is available at https://www.gbif.org/dataset/af18f3f8-f899-4c97-af47-8a110f856f92.

Morphological variations of Phrosina semilunata Risso, 1822 juveniles (Crustacea: Amphipoda: Hyperiidea), new evidence from the Gulf of Mexico.

Lack of knowledge of morphological variations during growth of amphipod crustaceans can result in misidentification of species. In this study, we advance the knowledge of morphological variations of juveniles of the monotypic genus Phrosina Risso, 1822 collected in the oceanic province of the southern Gulf of Mexico. The juveniles differed from the adults mainly in the morphology of pereopods 3 4 in that the carpal process is parallel to the propodus, also the rami of the pleopoda consist of only four segments, uropoda 3 are more lanceolate, and the uropoda bear a large prominent spine terminally. These morphological variations have not been described for the species previously. Therefore, the current observations enrich the description of P. semilunata in the early stages of growth and support the need for further taxonomical studiest that could help identify species at different stages of development.

A new species of the genus Hyalella (Crustacea, Amphipoda) from northern Mexico.

A new species, Hyalella tepehuana sp. nov., is described from Durango state, Mexico, a region where studies on Hyalella have been few. This species differs from most species of the North and South American genus Hyalella in the number of setae on the inner plate of maxilla 1 and maxilla 2, characters it shares with Hyalella faxoni Stebbing, 1903. Nevertheless, H. faxoni, from the Volcan Barva in Costa Rica, lacks a dorsal process on pereionites 1 and 2. Also, this new species differs from other described Hyalella species in Mexico by the shape of the palp on maxilla 1, the number of setae on the uropods, and the shape of the telson.

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.

Larval dispersal in three coral reef decapod species: Influence of larval duration on the metapopulation structure.

Most coral-associated decapod species have non-migratory adult populations and depend on their planktonic larvae for dispersal. This study examined the metapopulation structure of three decapod species with different pelagic larval duration (PLD) from twelve coral reef complexes of the Gulf of Mexico. The dispersion of larvae was analyzed through the use of a realistic numerical simulation of the Gulf of Mexico with the Hybrid Coordinate Ocean Model. To study the transport and dispersion of particles in near-surface waters, a particle-tracking subroutine was run using as input the currents from the model. The simulation consisted of the launch of 100 passive particles (virtual larvae) every 24 hours from each reef throughout five years, and tracked for as long as 210 days. Results indicated that species with a short PLD, Mithraculus sculptus (PLD 8‒13 days), had a weak connection among the reefs, but higher self-recruitment, especially on the narrow western shelf. The species with a longer PLD, Dromia erythropus (28‒30 days), had a stronger connection among neighboring reefs (< 300 km). Finally, the species with an even longer PLD, Stenopus hispidus (123‒210 days), had a wider potential distribution than the other species. Circulation on synoptic, seasonal and interannual scales had differential effects on the larval dispersal of each species. The metapopulation structure of M. sculptus and D. erythropus seemed to combine features of the non-equilibrium and the patchy models, whereas that of S. hispidus presumably fit to a patchy model. These findings support previous observations that indicate that species with longer PLD tend to occupy larger areas than species with short PLD, although recruitment of juveniles to the adult populations will also depend on other factors, such as the availability of suitable habitats and the ability to colonize them.

Hyalella cenotensis, a new species of Hyalellidae (Crustacea: Amphipoda) from the Yucatán Peninsula, Mexico.

In this study the first blind species of Hyalella for Mexico is described; it is the second in the genus to be recorded there. The new species is closer to the eyeless species: H. anophthalma Ruffo, 1957, H. muerta Baldinger, Shepard & Threloff, 2000, H. caeca Pereira, 1989, H. spelaea Bueno & Cardoso, 2011 in Cardoso et al. 2011, H. imbya Rodrigues & Bueno, 2012 in Rodrigues et al. 2012, but with no curved seta at the inner ramus of uropod 1, antennae 1 shorter than antennae 2, no apical setae on the telson and a characteristic dorsoposterior carina and three pappose setae on the inner plate of maxilla 1. The morphological intraspecific variations that can be found in this genus are discussed.