ABSTRACT The objective of this work was to evaluate the acute toxicity of the commercial herbicides Karmex® (diuron: DCMU 3-(3,4-dichlorophenyl)-1,1-dimethylurea) and Herbipol® (glyphosate: N-(phosphonomethyl) glycine) on the megalopae of Callinectes sapidus and measure their relative abundance in the association of larval and postlarval species of crustaceans from the estuary of the Jamapa River, Veracruz. Collections were made overnight using white light traps. Likewise, dissolved oxygen, pH, temperature, total dissolved solids, and salinity were measured in situ. It was found that the association of larvae and postlarvae consisted of Macrobrachium acanthurus, M. olfersii, Potimirim mexicana, megalopae of C. sapidus and Armases ricordi, and zoeas of Brachyura. In total, 559 and 1057 C. sapidus megalopae were collected in November and March 2019, respectively. Dissolved oxygen was 6 and 7 mg L−1, pH was 7 and 8, the temperature was 26 and 27°C, total dissolved solids were 700 and 1500 ppm, and salinity was 0.70 and 16 in November and March, respectively. Using Probit analysis, a 96 h LC50 of diuron (Karmex®) was 7.69 ± 1.07 mg L−1 in March and 6.64 ± 0.93 mg L−1 in November. The LC50 for glyphosate (Herbipol®) was 247.83 ± 34.54 mg L−1 in March and 288.18 ± 38.66 3 mg L−1 in November. The blue crab C. sapidus is tolerant to a wide range of physicochemical factors; however, it is sensitive in the postlarval stages, like other species of crustaceans, to the herbicides diuron and glyphosate, for which the megalopae can be used in ecotoxicological studies.

Abstract: In this study, the composition, distribution, and abundance of cumaceans collected in Isla Mujeres and Isla Contoy National Parks, Quintana Roo, Mexico, were evaluated. The specimens were collected with a scoop net (0.30 m wide by 0.48 m long and 330 µm mesh opening). The trawls were carried out on submerged vegetation in 10 m long transects parallel to the coastline. Additionally, at a station in Isla Mujeres, a white light trap with an intensity of 30 lm was used. The values of physicochemical parameters were measured in situ, which were within established by the official Mexican standard for uncontaminated waters; temperature (27.26 ± 0.64 °C); salinity (35.65 ± 0.21); dissolved oxygen (8.01 ± 0.88 mg L-1); total dissolved solids (22.82 ± 0.22 ppm); and pH (8.07 ± 0.15). Regarding the families Bodotriidae and Nannastacidae, a total of 7,590 specimens belonging to 5 genera and 18 species were identified. Cumella sp. “A” was the most abundant species with 5,364 specimens followed by Vaunthompsonia floridana with 1,391 specimens. Vaunthompsonia minor was recorded in 9 of the 11 sampling stations. The geographic distribution ranges of Cyclaspis mexicansis, Cumella achimae, C. bacescui, C. andri, C. caribbeana, C. croixensis, C. medeeae, and C. somersi were extended. The highest diversity and equitability occurred in Isla Mujeres (3.05 and 0.88 bits ind-1, respectively). The genus Vaunthompsonia was dominant in Isla Mujeres, while the genus Cumella was dominant in Isla Contoy.

Resumen: En este estudio se evaluó la composición, distribución y abundancia de cumáceos colectados en los Parques Nacionales Isla Mujeres e Isla Contoy, Quintana Roo, México. Los especímenes fueron recolectados con una red de cuchara (0,30 m de ancho por 0,48 m de largo y 330 µm de apertura de malla). Los arrastres se realizaron sobre vegetación sumergida en transectos de 10 m de largo paralelos a la línea de costa. Adicionalmente, en una estación de Isla Mujeres se utilizó una trampa de luz blanca con una intensidad de 30 lm. Se midieron los parámetros fisicoquímicos in situ, los cuales estuvieron dentro de los valores establecidos por la norma oficial mexicana para aguas no contaminadas; temperatura (27,26 ± 0,64 °C); salinidad (35,65 ± 0,21); oxígeno disuelto (8,01 ± 0,88 mg L-1); sólidos disueltos (22,82 ± 0,22 ppm); y pH (8,07 ± 0,15). En cuanto a las familias Bodotriidae y Nannastacidae, se identificaron un total de 7.590 ejemplares pertenecientes a 5 géneros y 18 especies. Cumella sp. “A” fue la especie más abundante con 5.364 ejemplares seguida de Vaunthompsonia floridana con 1.391 ejemplares. Se registró Vaunthompsonia minor en 9 de las 11 estaciones de muestreo. Se amplió el rango geográfico de distribución de Cyclaspis mexicansis, Cumella achimae, C. bacescui, C. andri, C. caribbeana, C. croixensis, C. medeeae y C. somersi. La mayor diversidad y equidad se presentó en Isla Mujeres (3,05 y 0,88 bits ind-1, respetivamente). El género Vaunthompsonia fue dominante en Isla Mujeres, mientras que el género Cumella fue dominante en Isla Contoy.

ABSTRACT Farmers have increased the production of food by using chemical substances such as diuron; however, these components affect the water quality and the species found in these ecosystems. Macrobrachium acanthurus and M. olfersii postlarvae present in the estuary of Río Jamapa, Veracruz were collected to measure the LC50 and LD50 using the herbicide Karmex (diuron: (3-(3,4-dichlorophenyl)-1,1-dimethylurea [DCMU]). The captures of the prawns were made with light traps. Acute toxicity bioassays were carried out at 96 h to determine the mean lethal concentration (LC50). In the experimental design, a geometric series was used considering the control and five concentrations of the herbicide (1.75, 3.5, 6.99, 14, and 28 mg/L). The data analysis was carried out with the Probit method. A maximum LC50 of 10.233 mg/L and LD50 of 8.221 mg/L of Karmex were obtained for M. acanthurus and a maximum LC50 of 9.242 mg/L and LD50 of 7.504 mg/L of Karmex were obtained for M. olfersii. The average lethal concentration was consistent with those of other crustaceans, such as Artemia salina and Daphnia. Based on the response in the bioassays, Macrobrachium acanthurus and M. olfersii postlarvae can be used in toxicology studies.

RESUMEN Los agricultores han aumentado la producción de alimentos mediante el uso de sustancias químicas como el Diurón; sin embargo, estos componentes afectan la calidad del agua y las especies que se encuentran en estos ecosistemas. Se recolectaron postlarvas de Macrobrachium acanthurus y M. olfersii presentes en el estuario del Río Jamapa, Veracruz para medir la CL50 y DL50 utilizando el herbicida Karmex (diuron: DCMU (3-(3,4-diclorofenil)-1,1-dimetilurea). Se realizaron las capturas de los langostinos con trampas de luz. Los bioensayos de toxicidad aguda se midieron a las 96 h para determinar la concentración letal media (CL50). En el diseño experimental se utilizó una serie geométrica considerando el testigo y cinco concentraciones del herbicida (1.75, 3.5, 6.99, 14 y 28 mg/L). El análisis de datos se realizó con el método Probit. Se obtuvo una CL50 máxima de 10.233 mg/L y una DL50 de 8.221 mg/L de Karmex para M. acanthurus y una CL50 máxima de 9.242 mg/L y DL50 de 7.504 mg/L de Karmex para M. olfersii. La concentración letal promedio fue consistente con la de otros crustáceos, como Artemia salina y Daphnia. Con base en la respuesta en los bioensayos, se pueden utilizar postlarvas de Macrobrachium acanthurus y M. olfersii en estudios de toxicología.

Resumen El género Eudevenopus incluye 4 especies válidas, son habitantes de aguas relativamente poco profundas en ambos lados de América. En este artículo se describe e ilustra una quinta especie, recolectada con una trampa de luz en Sisal, península de Yucatán. Eudevenopus winfieldi sp. nov. puede distinguirse de otras especies del género por el dactilo del pereópodo 7, que es tan largo como el própodo, el artejo 1 de la antena 1 del flagelo del macho con 2-4 estetes, un peine de 6 setas pectinadas distales en el margen posterodistal del carpo del gnatópodo 2, el pedúnculo del urópodo 3 tiene una sola seta intermedia robusta en el margen externo. También se proporcionan una clave de identificación y una tabla comparativa para contrastar la especie nueva con E. honduranus, que es la especie reconocida más cercana.

Abstract The genus Eudevenopus includes 4 valid species, inhabitants of relatively shallow waters in both sides of America. A fifth species, collected with a light trap in Sisal, Yucatán Peninsula is described and illustrated in this paper. Eudevenopus winfieldi n. sp. can be distinguished from other species in the genus by the pereopod 7 dactylus, which is as long as propodus, article 1 of flagellum antenna 1 of the male with 2-4 aesthetascs, a comb of 6 distal pectinate setae on the posterodistal margin of the carpus of gnathopod 2, and the uropod 3 peduncle, which has a simple robust intermediate seta on the external margin. An identification key and a comparative table are also provided to contrast the new species from E. honduranus, which is the closest recognised species.

ABSTRACT Background: The southern zone of the estuary of the Jamapa River, Veracruz, is a place of transition between the river and the marine environment to which sediments, compounds, and species of crustaceans are transported to the neritic zone where is the Parque Nacional Sistema Arrecifal Veracruzano. Objective: The responses of exposure of Potimirim mexicana postlarvae to diuron, glyphosate, and paraquat, as well as the relative abundance, diversity of the association of crustaceans, and values of temperature, salinity, oxygen, pH, and dissolved solids in the estuary were evaluated. Methods: Sampling was carried out with white light traps in November and March. Living Potimirim mexicana postlarvae were obtained from the samples to carry out the bioassays; the remaining individuals of the association were fixed in 70% alcohol for identification and quantification. The environmental factors were measured using a multiparameter Hanna HI 9828. Results: Dissolved oxygen was of 6-7 mgL-1, pH of 8-9, temperature of 26-27° C, total dissolved solids of 700-1,500 ppm and salinity of 0.70-16 ups. Environmental conditions permit the presence of Potimirim mexicana postlarvae. Six taxa were found: postlarvae of Macrobrachium acanthurus, M. olfersii and Potimirim mexicana, megalopae of Callinectes sapidus and Armases ricordi, and zoeae of Brachyura. Diversity ranged from 1.55 to 1.77 bits*individual-1, indicating an intermediate stability of the estuary. A total of 12,827 postlarvae of P. mexicana were obtained. The LC50 values of diuron, paraquat, and glyphosate were 5.94, 1.51, and 221.05 mgL-1, respectively. Conclusions: The values found here are consistent with those obtained by other authors for different species of crustaceans. Due to the important ecological in the food web of P. mexicana, its postlarvae can be used as sensitive test organisms in ecotoxicological studies.

RESUMEN Antecedentes: La zona sur del estuario del río Jamapa, Veracruz, es un lugar de transición entre el río y el medio marino al que se transportan sedimentos, compuestos y especies de crustáceos hasta la zona nerítica donde se encuentra el Parque Nacional Sistema Arrecifal Veracruzano. Objetivo: Se evaluaron las respuestas de exposición de las postlarvas de Potimirim mexicana a diurón, glifosato y paraquat, así como la abundancia relativa, diversidad de asociación de crustáceos y valores de temperatura, salinidad, oxígeno, pH y sólidos disueltos en el estuario. Métodos: El muestreo se realizó con trampas de luz blanca en noviembre y marzo. De las muestras se obtuvieron postlarvas vivas de Potimirim mexicana para realizar los bioensayos; los restantes individuos de la asociación se fijaron en alcohol al 70% para su identificación y cuantificación. Los factores ambientales se midieron utilizando un multiparamétrico Hanna HI 9828. Resultados: El oxígeno disuelto fue de 6-7 mgL-1, pH de 8-9, temperatura de 26-27 ° C, sólidos disueltos totales de 700-1,500 ppm y salinidad de 0,70-16 ups. Las condiciones ambientales permiten la presencia de postlarvas de Potimirim mexicana. Se encontraron seis taxones: postlarvas de Macrobrachium acanthurus, M. olfersii y Potimirim mexicana, megalopas de Callinectes sapidus y Armases ricordi y zoeas de Brachyura. La diversidad osciló entre 1,55 y 1,77 bits*individuo-1, lo que indica una estabilidad intermedia del estuario. Se obtuvieron un total de 12,827 postlarvas de P. mexicana. Los valores de LC50 de diurón, paraquat y glifosato fueron 5.94, 1.51 y 221.05 mgL-1, respectivamente. Conclusiones: Los valores aquí encontrados son consistentes con los obtenidos por otros autores para diferentes especies de crustáceos. Debido a la importancia ecológica en la trama trófica de P. mexicana, sus postlarvas pueden usarse como organismos de prueba sensibles en estudios ecotoxicológicos.

ABSTRACT The objective of this study was to analyze the brachyuran crab assemblages associated with shrimp fishing on the central-southern coast of Veracruz. Information was collected using 46 trawls organized within nine fishing quadrants. The total catch shrimp, bycatch, and discard were recorded and standardized (CPUE kg h−1). Value index by species, species richness, diversity using Shannon and Weaver index, and equitability were determined. A total of 3055 individuals were collected, which corresponded to nine families, 13 genera, and 14 species. Achelous spinicarpus species were identified at the greatest relative abundance (77.74%). Four new species records for the zone: Hepatus pudibundus, Iliacantha liodactylus, Leiolambrus punctatissimus, and Platylambrus granulatus. Species richness varied according to fishing quadrant and depth interval assessed. The highest value of species richness was eight, and observed Margalef species richness index values ranged from 0 to 2.23. The diversity values ranged from 0 to 2.41 bits ind−1; this may indicate that a few species share the greatest impact of trawling. The presence of lagoon systems was determined to define a portion of the composition of the assemblage. Understanding assemblage structure is important to improve knowledge on the impact of shrimp trawling activity on the ecosystem.

Abstract: The population structure, growth, fertility and survival of Nototropis minikoi and Ampithoe longimana in Isla Contoy and Isla Mujeres from Mexican Caribbean were analyzed. A total of 2,815 amphipods of both species were collected: 1,407 of Nototropis minikoi and 1,408 of Ampithoe longimana. The temperature showed values of 26 to 27 °C, salinity of 35 to 36 units and dissolved oxygen of 6 to 9 mg L-1. The juveniles represented the highest percentage with 55 to 73% in N. minikoi and 57 to 67% in A. longimana. With the Bhattacharya method, 4 to 5 modal classes were found. With the von Bertalanffy model, the greatest maximum length of 10.88 mm (k= 0.35) and 14.54 mm (k= 0.24) in the females of N. minikoi and A. longimana were found, respectively. The average number of eggs was 6.83 ± 4.50 to 8.55 ± 5.22 in N. minikoi and 7.55 ± 4.82 to 8.33 ± 3.79 in A. longimana. Survival was 13.70 and 36.63% for N. minikoi and 13.31 and 28.11% for A. longimana, which corresponds to species with “r” strategy. The results showed a trade-off between the population parameters, since at a slow growth rate and a greater number of modal classes greater maximum sizes are reached.

Resumen: Se analizó la estructura de la población, el crecimiento, la fecundidad y la supervivencia de Nototropis minikoi y Ampithoe longimana en Isla Contoy e Isla Mujeres del caribe mexicano. Se midieron la temperatura, salinidad y oxígeno disuelto in situ. Se recolectaron un total de 2.815 anfípodos de ambas especies: 1.407 de Nototropis minikoi y 1.408 de Ampithoe longimana. La temperatura presentó valores de 26 a 27 °C, salinidad de 35 a 36 unidades y oxígeno disuelto de 6 a 9 mg L-1. Los juveniles representaron el mayor porcentaje con 55 a 73% en N. minikoi y del 57 a 67% en A. longimana. Con el método de Bhattacharya se encontraron de 4 a 5 clases modales. Con el modelo de von Bertalanffy se encontró que las hembras presentaron la mayor longitud máxima con 10,88 mm (k= 0,35) y 14,54 mm (k= 0,24) en N. minikoi y A. longimana, respectivamente. El promedio de huevos fue de 6,83 ± 4,50 a 8,55 ± 5,22 en N. minikoi y 7,55 ± 4,82 a 8,33 ± 3,79 en A. longimana. La supervivencia fue de 13,70 y 36,63% para N. minikoi y de 13,31 y 28,11% para A. longimana, lo cual corresponde a especies con estrategia “r”. Los resultados evidenciaron una relación costo-beneficio entre los parámetros poblacionales, dado que a una tasa de crecimiento lenta y un mayor número de clases modales se alcanzan tamaños máximos mayores.

Abstract We evaluated the composition, distribution, and abundance of the decapod genera at different developmental stages of larvae and adult macro-crustaceans along the coastline of the Parque Nacional Sistema Arrecifal Veracruzano, SW Gulf of Mexico. Collections were made using light traps. Temperature, salinity, oxygen, and pH were measured in situ. The samples were fixed with 70 % alcohol, separated, and identified by developmental stage and genus level with specialized literature. The Olmstead-Tukey test, the Shannon-Wiener diversity index, and Pielou equitability test were applied. Canonical correlation and cluster analysis were performed. In total, 20,049 individuals of 56 stage-genera were collected, with Potimirim Holthuis, 1954 postlarvae being the most abundant ones. The most abundant taxa were Potimirim at Playa Martí, Macrobrachium Spence Bate, 1868 at Plaza de la Soberanía, and Pachygrapsus Randall, 1840 at Playa Villa del Mar and Playa Tortugas. At Playa Villa del Mar, the highest diversity was found (3.47 bits*individuals-1), and this is related to the complexity of the site. In May, the greatest diversity (3.64 bits*individuals-1) was found, related to the time of reproduction of most of the stage-genera. Most stage-genera were classified as rare. Cluster analysis resulted in two groups, one containing taxa found in cold and wet months and the other of taxa found in dry months. Thus, the dynamics of the taxocene structure is determined by the lifecycles of the species, responding to the migration, reproduction, and colonization of each stage-genera.

ABSTRACT Background: The Parque Nacional Sistema Arrecifal Veracruzano (PNSAV) is in the southern Gulf of Mexico and supports an important shrimp fishery based on three species of Dendrobranchiata: the brown shrimp, Penaeus aztecus, the white shrimp, P. setiferus and the pink shrimp, P. duorarum. Objective: Analyze the distribution and abundance of P. aztecus during the mysis stage and determine its relationship with environmental factors in the PNSAV. Methods: We measured temperature, salinity, and dissolved oxygen in situ. The planktonic samples from four transects were collected during cold fronts and rainy weather conditions from 2011 to 2013. Results: In rainy conditions the temperature varied from 27.49 ± 0.46 to 29.98 ± 0.02°C, salinity from 32.18 ± 0.06 to 35.40 ± 0.52, and dissolved oxygen from 3.64 ± 0.13 to 6.18 ± 0.64 mgL-1; during cold fronts the temperature varied from 23.21 ± 0.05 to 25.74 ± 0.37 °C, salinity from 34.59 ± 0.39 to 35.84 ± 0.17, and dissolved oxygen from 4.04 ± 0.06 to 6.02 ± mgL-1. The highest average density with 6,938 ± 326 mysis 100 m−3, was found during rainy season in 2011 in the southern transect nearshore, followed by 3,321 ± 339 mysis 100 m−3 in the offshoresouth-central transect during cold fronts weather conditions in 2013, and 3,056 ± 236 mysis 100 m−3 in the south-central foreshore transect during cold fronts weather condition in 2011. Conclusions: The highest density of P. aztecus during mysis stage was recorded in southward foreshore area from PNSAV, during rainy conditions and related to large values of dissolved oxygen concentrations.

RESUMEN Antecedentes: El Parque Nacional Sistema Arrecifal Veracruzano (PNSAV) está ubicado en el sur del Golfo de México y soporta una importante pesquería de camarones basada en tres especies de Dendrobranchiata: el camarón café, Penaeus aztecus, el camarón blanco, P. setiferus y el camarón rosado, P duorarum. Objetivo: Analizar la distribución y abundancia de P. aztecus en estadio de mysis y determinar su relación con los factores ambientales en el PNSAV. Métodos: Se midió la temperatura, la salinidad y el oxígeno disuelto in situ. Se recolectaron muestras planctónicas de cuatro transectos durante frentes fríos y condiciones climáticas lluviosas de 2011 a 2013. Resultados: La temperatura varió de 27.49 ± 0.46 a 29.98 ± 0.02 °C, la salinidad de 32.18 ± 0.06 a 35.40 ± 0.52 y el oxígeno disuelto de 3.64 ± 0.13 a 6.18 ± 0.64 mgL-1 en época de lluvias. Durante los frentes fríos, la temperatura varió de 23.21 ± 0.05 a 25.74 ± 0.37 °C, la salinidad de 34.59 ± 0.39 a 35.84 ± 0.17 y el oxígeno disuelto de 4.04 ± 0.06 a 6.02 ± mgL-1. La densidad media más alta fue de 6,938 ± 326 mysis 100 m−3, que se encontró durante las lluvias en 2011 en el transecto sur, cercano a la costa, seguido por 3,321 ± 339 mysis 100 m−3 en el transecto centro-sur, costa afuera durante los frentes fríos en 2,013 y 3,056 ± 236 mysis 100 m−3 en el transecto centro-sur durante los frentes fríos en 2011, en la zona de la costa. Conclusiones: La mayor densidad de mysis de P. aztecus se registró en la zona de playa al sur del PNSAV, durante las condiciones de lluvia y se relacionó con el aumento de las concentraciones del oxígeno disuelto.

RESUMEN Se efectuó un examen helmintológico a 14 especímenes de Eucinostomus melanopterus (mojarra bandera) y 19 Eugerres plumieri (mojarra rayada), de los cuales se recolectaron un total de 461 helmintos. Se identificaron 12 taxones (cinco a nivel de especie, cinco a género y dos a familia) como sigue: cuatro monogéneos, cinco digéneos (cuatro adultos, una metacercaria), un céstodo (plerocercoide) y dos nemátodos (larvas). La prevalencia más alta fue para Neodiplectanum mexicanum (29 %) en E. melanopterus y Aristocleidus hastatus (37 %) en E. plumieri. Ambos hospederos comparten el 50 % de los taxones de parásitos. Ninguno de los helmintos representa un riesgo zoonótico.

ABSTRACT A helminthological examination was carried out on 14 specimens of Eucinostomus melanopterus (flagfin mojarra) and 19 Eugerres plumieri (striped mojarra), of which a total of 461 helminths were collected. As a result, and 12 taxa were registered (five species, five genus and tow family), as follows: four monogeneans, five digeneans (four adults, one metacercaria), one cestode (larva) and tow nematodes (larvae). The highest prevalence was for Neodiplectanum mexicanum (29 %) infecting E. melanopterus and Aristocleidus hastatus (37 %) infecting E. plumieri. Both hosts shared 50 % of recorded species, and none of the identified helminthes represents a zoonotic risk.

Abstract In this study we analyze both seasonal and inter-annual variations in the community parameters of Brachyura zoea I in the Parque Nacional Sistema Arrecifal Veracruzano. Planktonic samples from four transects were collected during three weather conditions: cold fronts; rainy and dry conditions in 2011 and 2012; and cold fronts and dry conditions in 2013. We measured temperature, salinity, and dissolved oxygen, in situ, to determine whether these parameters could explain the observed variations in the community patterns of brachyuran zoea I. We collected zoeae I of 18 species of brachyurans. The dominant species were Libinia dubia H. Milne Edwards, 1834; Menippe nodifrons Stimpson, 1859; and Callinectes sapidus Rathbun, 1896. The temperature and dissolved oxygen were the highest during the rainy conditions and the salinity during the dry conditions in the southern transects. The highest species richness (14) and diversity (2.97 bits individual-1) were found in central transects during cold front conditions. However, we found the highest species richness and diversity during the dry conditions, in the southern transects. Libinia dubia presented the highest density during cold fronts with 1592 ± 127 zoeae 100 m−3 in the northern transect, followed by C. sapidus in the north-central transect, this was observed for both species in the offshore zone. In conclusion, the parameters of the community of zoea I were influenced by the physical parameters measured in each sampling zone.

Abstract The biodiversity, abundance and distribution of benthic amphipods in the reefs of Sisal and Madagascar, including the adjacent coastline, SE of the Gulf of Mexico, were analyzed. Amphipods were collected (12,986), belonging to 95 species, 51 genera, 32 families and 3 suborders (Amphilochidea, Colomastigidea and Senticaudata), between 0.5 and 20 m depths. Americorophium aquafuscum, Lepidepecreum magdalenensis, Leucothoe saron, Photis lecroyae, and Seba robusta were new records for the Gulf of Mexico. Apocorophium louisianum, Ericthonius brasiliensis, and Ampithoe ramondi accounted for 50% of the abundance. Two subgroups of benthic amphipods were found; one of species associated with reef patches and another of species present in the adjacent coastline. In this study, biodiversity and abundance were higher compared to other reefs in the Gulf of Mexico, attributed to the coverage of macroalgae and a higher amount of coral rock; unlike the adjacent coastline that is attributed to the wood debris. This is the first research on benthic amphipods in the Sisal Reef System, Yucatán, increasing the number of documented species for the Gulf of Mexico from 315 to 319, and from 199 to 207 species for the southeast sector.

Resumen Se analiza la biodiversidad, abundancia y distribución de los anfípodos bentónicos en los arrecifes de Sisal y Madagascar, incluyendo la línea de costa adyacente, SE del golfo de México. Se recolectaron 12,986 anfípodos, pertenecientes a 95 especies, 51 géneros, 32 familias y 3 subórdenes (Amphilochidea, Colomastigidea y Senticaudata), entre los 0.5 y 20 m de profundidad. Americorophium aquafuscum, Lepidepecreum magdalenensis, Leucothoe saron, Photis lecroyae y Seba robusta fueron registros nuevos para el golfo de México. Apocorophium louisianum, Ericthonius brasiliensis y Ampithoe ramondi representaron 50% de la abundancia. Se encontraron 2 subgrupos de anfípodos bentónicos; uno de especies asociadas a manchones arrecifales y otro de especies presentes en la línea de costa adyacente. En este estudio, la biodiversidad y abundancia fueron mayores comparadas con otros arrecifes del golfo de México, atribuido a la cobertura de las macroalgas y mayor cantidad de roca coralina; a diferencia de la línea de costa adyacente que se atribuye a los restos de madera. Esta es la primera investigación sobre los anfípodos bentónicos en el Sistema Arrecifal Sisal, Yucatán, incrementando el número de especies documentadas para el golfo de México de 315 a 319, y de 199 a 207 especies para el sector sureste.

Abstract In this study, the larval development of Libinia rhomboidea Streets, 1870 under laboratory conditions is described and compared with the description of Libinia spinosa H. Milne Edwards in Guérin, 1832, Libinia dubia H. Milne Edwards, 1834, and Libinia emarginata Leach, 1815 published by other authors. The ovigerous females collected released larvae asynchronously. Two zoeas and one megalopa stage were obtained. Larval development required 13 to 14 days at 20.5 - 22.0°C and 32 - 35 psu of salinity. The differences in L. rhomboidea with respect to the other three species are the following: in the first zoea, the total length and carapace length were greater and the number of setae on the basial endite of the maxillula was different; in the second zoea the size of the endopod and the number of setae on the scaphognathite of the maxilla were greater; in the megalopa, the total length and carapace length were both greater, while the number of setae on the scaphognathite of the maxilla was less. A great similarity between L. rhomboidea and L. dubia was found; however, it is possible to distinguish the larval morphology of L. rhomboidea from the three species compared.

ABSTRACT The present study provides information on the morphology of stomatopod larvae found in two different reef systems which are also considered national parks: the Sistema Arrecifal Veracruzano (SAVNP) and Arrecife Puerto Morelos (APMNP). Zooplankton samples were collected at 26 stations of the SAVNP and four stations of the APMNP. Stomatopod larvae were identified and classified by their larval stage. We found representatives of three stomatopod superfamilies: the superfamily Gonodactyloidea Giesbrecht, 1910 was represented by Neogonodactylus oerstedii (Hansen, 1895), Neogonodactylus wennerae Manning and Heard, 1997, and Pseudosquillidae genus and species indeterminate; the superfamily Lysiosquilloidea Giesbrecht, 1910 was represented by Lysiosquilloidea genus and species indeterminate, Lysiosquilla sp., Lysiosquilla scabricauda (Lamarck, 1818) and Nannosquilla adkisoni Camp and Manning, 1982; the superfamily Squilloidea was represented by larvae of Alima neptuni (Linnaeus, 1768), Squilla spp., and Squilla empusa Say, 1818. We were able to identify and describe four stages of larval development for representatives of these superfamilies. This is the first study describing several stages of larval development of different species of the stomatopods from the Gulf of Mexico and Caribbean Sea.

ABSTRACT The objective of this study was to describe the morphology of Clibanarius antillensis Stimpson, 1859 megalopae collected in the vicinity of Isla Sacrificios, Mexico, and compare it to previous descriptions originated from Brazilian and Panamanian specimens raised in laboratory conditions. We found four meristic differences between the Brazilian and the Panamanian and Mexican populations with the Brazilian population: the outer flagellum of antennule in the Panamanian and Mexican populations has more aesthetascs on the second, third, and fourth segments of the outer flagellum (0, 6, 5, 3, 0) than the Brazilian population (0, 4, 4, 2, 0); the maxilla has more setae on the scaphognathite in the Brazilian specimens (70) than in the Mexican and Panamanian specimens (49-62); the crista dentata of the third maxilliped is formed by only three denticles in the Brazilian specimens, while 4 or 6 denticles form the same structure in the Panamanian and Mexican populations; there are fewer number of setae on the endopod of the uropod in the Brazilian population. The differences may be explained by intraspecific variation.