Our study provides a checklist of 36 crustacean decapods from the Mexican tropical Pacific coastline. Most of the species were previously recorded from coral communities in the Gulf of California. Data were obtained by visual censuses of coral communities and some specimens were collected by extractions of coral branches (approximately eight liters of coral volume). We found new geographic records for three species from the Eastern Pacific and seven species that have extended ranges into Mexican waters. Only one species is documented with a northerly range from Central America to Mexican waters.

Introduction: Invasive species are considered the second cause of extinction of native species after habitat loss. The impacts of invasive species have serious economic implications since the presence of this type of species can result in a decrease in ecosystem services granted to humans. In marine systems, some human activities such as maritime transport and aquaculture have favored the dispersion of invasive species, especially those with commercial importance. This paper describes the potential distribution of the tiger shrimp, Penaeus monodon, an invasive species along the American Atlantic coast. Objective: To describe a potential distribution model of Penaeus monodon in the American Atlantic region and compare the environmental characteristics of this region with those of the Indo-Pacific original niche conditions. Methods: Using geographic and environmental data, we constructed and tested three models to determine the efficiency of MaxEnt v. 3.3 software in predicting new areas for the distribution of this invasive shrimp species. Geographic data were downloaded from such web sites as the Global Biodiversity Information Facility, the Ocean Biogeographic Information System, and the United States Geological Survey, as well from literature. Environmental data were downloaded from Bio-Oracle v2.0 data base. The three tested models were: 1) the first was created using only recordings of Penaeus monodon from the Indo-Pacific (its origin zone) and then projected to the Atlantic (native model); 2) the second was built using only recordings from the invaded area; the training and projection area of this model was the Atlantic (invasive model); 3) the third included recordings from both the Indo-Pacific and Atlantic regions, and the model was trained and projected jointly in both areas (complete model). We extracted the values of the three models for each tiger shrimp sightings in the invaded area; sightings with values ³ 0.5 were considered as valid prediction of occurrence of the species. Results: We found that the following variables explained 80 % of species distribution: phosphates from the ocean surface, coastal type, chlorophyll a, and maximum bottom temperature. In terms of the models’ ability to predict the occurrences reported in the Atlantic, results were as follows: Native model had a prediction index of 40 %; Invasive model was able to predict 81 % of recordings; and complete model predicted 92 % of total occurrences reported in the invaded area. Conclusions: Our findings suggest that based on the complete model, the countries where the tiger shrimp could establish itself are Mexico and Cuba. Continuous monitoring and conservation actions are relevant in the countries where this species is currently established, as well of those countries with potential for invasions.

El blanqueamiento del coral es consecuencia de un estrés natural o antropogénico sobre los arrecifes. En la región del Pacífico tropical este, el blanqueamiento del coral se asocia comúnmente con el incremento de la temperatura superficial del mar, pero también se puede presentar por temperaturas bajas. A principio de 2008 se registró una anomalía de temperatura extraordinariamente baja, de hasta 1.8 °C menor al promedio registrado en los últimos 25 años, que se manifestó con un severo blanqueamiento de corales en varias localidades al sur del golfo de California, alcanzando cifras de hasta el 90% del coral blanqueado. El objetivo del presente trabajo fue describir los cambios en el ensamblaje de decápodos asociados a los arrecifes en la región afectada. Las bahías de La Paz (24° N) y Loreto (26° N) fueron visitadas antes, durante y después del evento, realizándose censos visuales en 6 sitios de cada bahía. Los resultados muestran que la riqueza y dominancia de decápodos cambió por efecto del blanqueamiento. La afectación fue diferencial entre ambas localidades: la fauna coralina de la región de Loreto fue más afectada que la de bahía de La Paz y los cambios en los ensamblajes de decápodos fueron diferentes.

A recent molecular study on pelagic nudibranchs showed that Glaucus marginatus (Reinhardt and Bergh, 1864) is a complex of three cryptic species, whereas the congener G. atlanticus (Forster, 1777) remain as one species. The objective of the present study was to determine the identity of pelagic nudibranchs collected in the Gulf of California using both molecular and traditional taxonomy. New DNA sequences (COI) and GenBank data were used to confirm the specimens' identity as G. atlanticus. Records from G. atlanticus were obtained from databases to determine the species geographic range. Present results increase that range northwards by approximately 150 km in the Gulf of California. Molecular data indicate that G. atlanticus from the Gulf has a wide infl uence from populations from the North and South Pacific and Indian Oceans. There is no current evidence of other cryptic species.

Diatoms are among the most common epibionts and have been recorded on the surfaces of various living substrates, either plants or animals. However, studies on them are still scarce in view of the many substrata available. In this study, epibiotic diatoms living on Callinectes bellicosus were identified for the first time from a subtropical coastal lagoon in Northwest Mexico. We tested the null hypothesis that the diatom flora living on the carapaces of C. bellicosus would not be similar to that recorded for mangrove sediments, its typical habitat. The epibiotic diatoms were brushed off from the carapaces of two specimens, acid-cleaned, mounted in synthetic resin, and identified based on frustule morphology. This way, 106 taxa from 46 genera were recorded, including 25 singletons, and 6 new records for the Mexican northwest region. The best-represented genera were Nitzschia (10 taxa), Mastogloia (9), Diploneis (8), Navicula (7), Amphora (5), Cocconeis (5), Tryblionella (4), and Gyrosigma (4). Species composition included 93% of local taxa, thus refuting the proposed hypothesis and supporting the alternate one. Although the estimated species richness was lower than that in sediments, it deems the green crab carapace a favorable substrate for the growth of benthic diatoms.