Abstract A new epigean asellid isopod, Caecidotea contrerasbalderasi sp. nov. is described from Nayarit, northwestern Mexico. This new species has morphological characters belonging to two different types of environments, both depigmentation and anophthalmia, indicators of organisms adapted to live in constant darkness as cavernicolous species. Despite showing characteristics of hypogean species, the new taxon does not show elongation of appendages, such as pereiopods, antennae or uropods. Its pleopod IV exopod lacks false sutures. This is a new pattern type “C”, and differs from that observed in types A and B. The description of this new species brings a new total of 101 species and three subspecies, for the genus Caecidotea in North America all morphologically poorly differentiated and with a restricted distribution.

Summary Tuberose (Polianthes tuberosa L.) is an ornamental plant produced worldwide, mainly as a cut flower. A limitation of tuberose production is the control of flowering time, for which different strategies have been evaluated, one of these is the pretreatment of the corms with temperature. In this study, corms of tuberose were subjected to two storage temperatures (4 and 27 °C) for 4, 5, 6 and 7 weeks, in addition to two controls: corms kept at room temperature (T0) and corms with a pretreatment with GA3 (200 ppm). The variables evaluated were meristem length (ML), meristem width (MW), days to sprouting (DS), days to flowering (D), flower stem length (FSL), flower stem diameter (FSD), spike length (SL) and number of flowers (NF). The fastest growth and differentiation of the meristem occurred after the establishment of corms in the greenhouse; treatments at 27 °C advanced the sprouting of the first leaves. The treatments of 27 °C for six weeks and 4 °C for one week showed fewer days to flowering (100.8 and 104.0 respectively). In general, corms treated at 27 °C showed greater homogeneity in the harvest curve without affecting the rest of the variables evaluated, which is important because such treatments can be used to control tuberose flowering without affecting quality.

Resumen El nardo (Polianthes tuberosa L.) es una planta ornamental producida en todo el mundo, principalmente como flor de corte. Una limitante de la producción de nardo es el control del tiempo de floración, para lo cual se han estudiado diferentes estrategias, una de estas es el pretratamiento de los cormos con temperaturas. En el presente estudio, cormos de nardo se sometieron a dos temperaturas de almacenamiento (4 y 27 °C) por 4, 5, 6 y 7 semanas, además de dos testigos: cormos mantenidos a temperatura ambiente (T0) y cormos con pretratamiento con AG3 (200 ppm). Las variables evaluadas fueron el largo del meristemo (LM), ancho del meristemo (AM), días a la brotación (DAB), días a floración (DAF), longitud del tallo floral (LT), diámetro del tallo (DT), longitud de la espiga (LE) y número de flores (NF). El mayor crecimiento y diferenciación del meristemo se presentaron después del establecimiento de los cormos en invernadero; los tratamientos a 27 °C adelantaron la brotación de las primeras hojas. Los tratamientos de 27 °C por 6 semanas y de 4 °C por una semana presentaron menores días a floración (100.8 y 104.0 respectivamente). En general, los cormos tratados a 27 °C presentaron mayor homogeneidad en la curva de cosecha sin afectar el resto de las variables evaluadas, lo cual es importante porque tales tratamientos pueden usarse para controlar la floración de nardo sin afectar la calidad.

Abstract Antioxidant capacity (AC) was determined by the ABTS method and DPPH, and total phenol content (TPC) in dehydrated plant material, in infusions and in residues (plant material after preparing the infusion) of white, black, red, green, spearmint, stevia, lemon grass and chamomile teas to which stevia leaves were added or not added; addition of processed stevia powder was also tested. Three independent experiments were set up: with dehydrated plant material, with infusions and with residues. For the case of dehydrated plant material, white tea had the highest TPC (10813.5 mg GAE/100g) and AC by the ABTS method (1183.3 µM TE/g) and DPPH method (1525.0 µM TE/g). In infusions, black tea had higher TPC (180.82 µg GAE/ml) and AC by the methods ABTS and DPPH (0.6114 and 2.5983 µM TE/ml, respectively). In residues, TPC was higher in white tea, while green tea had the highest AC values. AC of dehydrated plant material increased when stevia leaves were added, according to the DPPH and ABTS methods, but not in residues by ABTS. Addition of stevia leaves in infusions increased AC in white, lemon grass, chamomile and stevia teas by the ABTS method and in spearmint, black, red, and green teas with the DPPH method.

Abstract An adult female of the Jewel-Box clam crab Gemmotheres chamae (Roberts, 1975) was collected from a shrimp trawl during a biological exploration off Campeche coast, Mexico. This finding represents its first record in the Gulf of Mexico and the second locality for this species along the Atlantic coast of America, the first being from off North Carolina, U.S.A. As an adult, G. chamae has a soft, thin carapace, and a subconical protuberance on article 1 of the antennae (with the nephridiopore of the antennal gland), so it is considered to belong to the Pinnotherinae sensu stricto. G. chamae and Nannotheres moorei Manning and Felder, 1996 (Atlantic) are the only members of the American Pinnotherinae sensu stricto that have the maxilliped 3 with a 2-segmented palp. The asymmetry of pereiopod 3 is confirmed, as well as that of the pereiopod 4, but the right legs are the longest. All these features are diagnostic for G. chamae.

Abstract We describe the presence, structure, number of eggs, and hatching success of Rallus obsoletus levipes (Ridgway´s rail), a bird species protected in Mexico and the USA, during the 2016 to 2018 nesting seasons at Estero Punta Banda (EPB), Ensenada, Baja California, Mexico. The number of eggs per nest was 6, 7, or 8, and hatching success 0, 75, or 100%. We document the presence, abundance, and density of Geukensia demissa, (Atlantic ribbed mussel) an invasive bivalve in the estuary study area. G. demissa density per marsh area: Internal Marsh (MI) 5.36/m2, Middle Marsh (MM) 6.94, and External Marsh (ME) 3.52. G. demissa density isn’t independent of marsh area, p < 0.001. We document the dead of two R. o. levipes chicks found trapped and dead in the G. demissa valves during EPB high tides. We did not find an association between dominant vegetation, Spartina folios and Salicornia spp. and the presence of G. demissa. Its presence seems to be independent of vegetation presence. The permanence of R. o. levipes at EPB depends on a better knowledge of the population and its interaction with G. demissa and other threats at EPB. We discuss the role of G. demissa in the future of R. o. levipes at EPB. New proposals have to be made such that sites with an elevation higher than the mean tide level are considered as critical for the nesting and survival of the bird.

Resumen Describimos la presencia, estructura, número de huevos y éxito de eclosión de los nidos de Rallus obsoletus levipes (rascón picudo), un ave protegida en México y Estados Unidos, durante las temporadas de anidación de 2016 a 2018 en el Estero de Punta Banda (EPB), Ensenada, Baja California, México. El número de huevos por nido fue de 6, 7 u 8 y el éxito de eclosión de 0, 75 o 100%. Asimismo reportamos la abundancia y densidad de Geukensia demissa (mejillón rayado, un bivalvo invasor) en el sitio de estudio. Las densidades de G. demissa por zona de marisma fueron: Marisma Interna (MI) 5.36/m2, Marisma Media (MM) 6.94 y Marisma Externa (ME) 3.52. El número de bivalvos no es independiente de la zona de marisma, p < 0.001. Documentamos la muerte de dos polluelos de R. o. levipes encontrados muertos y ahogados en las valvas de G. demissa durante mareas altas en el EPB. No encontramos una asociación entre la cobertura vegetal dominante, Spartia foliosa y Salicornia spp. y la presencia de G. demissa. Su presencia parece ser independiente de la presencia de vegetación. La permanencia de R. o. levipes en el EPB depende de un mejor conocimiento de la población y sus interacciones con G. demissa y otras amenazas en el EPB. Discutimos el rol de G. demissa en el futuro de R. o. levipes en el EPB. Se deben elaborar propuestas para que los sitios con una elevación mayor al nivel medio de marea sean considerados como críticos para la anidación y persistencia del ave.

Abstract Virgin oil from avocados (Persea americana Mill.) is obtained by mechanical processes after pulp malaxation at temperatures that minimize oxidation and improve separation. The objective of this study was to assess the effect of time (0, 20, 30, 40, 60, 120 and 180 min) and temperature (40 and 50 °C) conditions during pulp malaxation on extraction yield, nutritional value (normalized fatty acid profile) and specific extintion (K232 and K270) of virgin oil extracted under laboratory conditions from avocados cultivated in southern Jalisco, Mexico. When pulp was malaxated for 120 min at 40 and 50 °C, a larger proportion of oil was extracted (82.9 ± 0.3% and 80.2 ± 0.8%, respectively). We observed that the normalized percentage of the fatty acids linoleic (18 ± 2%) and linolenic (1.2 ± 0.2%) decreased with mixing time, while that of palmitoleic (9 ± 1%), oleic (51.6 ± 1.2%) and stearic (0.5 ± 0.1%) remained without change. The ω-6:ω-3 ratio (15 ± 1) was higher than the recommended values but similar to those reported as favorable for health. Specific extinction (K232, 2.2 ± 0.3 and K270, 0.20 ± 0.03) indicate that the oxidation level remained low. Malaxation at 40 or 50 °C did not significantly alter the characteristics of the oil, but time significantly affected yield.

Abstract Background Artisan fishermen along the southern Sinaloa coast catch alternative species, for example the Grapsus grapsus rock crab without biological and fishing controls, when their catches are reduced or when the season for catching certain fish has ended. Goals We analyzed the size structure and biometric relationships of G. grapsus on Lobos, Venados, and Pájaros Islands of Mazatlán Bay, Sinaloa, Mexico. Methods The cephalothorax width (CW) and weight (W) were analyzed during a one-year period (March 2012-February 2013). Results 926 organisms were collected (519 males y 407 females). Pájaros Island had the greater percentage (37.4%) of collected organisms, followed by Lobos (34.2%), and Venados (28.4%) Islands. The greatest values were CW=74.5 mm recorded at Pájaros Island and W = 138.2 g at Venados Island and the lowest values were CW=13.9 mm at Pájaros Island and BW =1.1 g at Lobos Island. Means of CW and W were 41.4 mm and 31.5 g, respectively. The means of CW and W were statistically different between the islands (CL, p = 0.009; W, p < 0.015). Conclusions High determination coefficients between the variables were obtained, indicating isometric growth. Specimens of G. grapsus increase their size quickly and their weight very slowly.

Resumen Antecedentes En el intermareal de las islas de la bahía de Mazatlán es común que los pescadores ribereños capturen al cangrejo roca Grapsus grapsus sin un control que regule sus tallas y su extracción. Objetivos Se analizaron las tallas y relaciones biométricas de G. grapsus en las islas Lobos, Venados y Pájaros (Sinaloa, México), entre marzo de 2012 y febrero de 2013 con muestreos mensuales y nocturnos durante la bajamar. Métodos Por cada isla se recolectaron al azar 30 organismos, cuyo sexo se determinó por dimorfismo sexual y se registraron AN, LT y AL (mm) y PT (g). Se realizaron histogramas de frecuencia y se correlacionaron las variables. Resultados Se recolectaron 926 organismos: 519 machos y 407 hembras. El mayor porcentaje en isla Pájaros (37.4%), seguido de Lobos (34.2%) y Venados (28.4%). Los valores máximos fueron para AN de 74.5 mm (Pájaros) y PT de 138.2 g (Venados), y los mínimos para AN de 13.9 mm (Pájaros) y en PT 1.1 g (Lobos). Los promedios en AN fueron 41.4 mm y en PT 31.5 g, las medias de AN presentaron diferencias entre islas (p = 0.009) y en PT (p < 0.015). La mayor incidencia modal en AN fue de 32.5 a 52.5 mm y en PT de 11 a 21 g. Conclusiones Se obtuvieron coeficientes de determinación altos entre las variables y presentaron un crecimiento isométrico. Además, los organismos de G. grapsus incrementan rápidamente de talla y muy lentamente de peso.

Because the male holotype of Pinnotheres bipunctatus possesses a carpus of the third maxilliped larger than the propodus, the dactylus disto-medially inserted on the ventral margin of this latter article extending far beyond its tip, and a laterally expanded telson, wider than the sixth abdominal somite, it is excluded from Pinnotheres and assigned to Pinnaxodes (type species P. chilensis). Although males of these species can morphologically be separated, the holotype of P. bipunctatus resembles a juvenile, consequently, a categorical taxonomic distinction between this species and P. chilensis will require a comparative morphological study of the preadult stages of the latter species. A distributional checklist and host of the Pinnotheridae recorded for the Peru-Chile region is included, along with a list and the taxonomic status of the five genera and 53 species of Crustacea described by Hercule Nicolet in the "Physical and Political History of Chile".

Freeze-drying technology is the best dehydration process to preserve shelf-life and allowing avocado to maintain its sensorial and nutritional characteristics. The aim of this work was to determine if the freeze-drying and production condition have an effect on the nutritional quality of the avocado pulp grown in rain-fed and irrigation orchards. Four treatments were applied: non-freeze-dried rain-fed fruits, non-freeze-dried irrigation fruits, freeze-dried rain-fed fruits and freeze-dried irrigation fruits. Results showed that the fruit is made up of 71.4%, 16%, and 12.6% pulp, seed and skin, respectively. The pulp is made up of 71.51%, 19.96%, 2.81%, 0.51% and 1.51% water, lipids, ashes, crude fiber and protein, respectively. Avocado oil is composed by 61%, 18.8%, 11.6% and 7% oleic, palmitic, linoleic, and palmitoleic fatty acids, respectively. The freeze-drying decreased the linoleic acid by 1.43 g/100g. Under rain-fed conditions 4% and 13% less total fat and oleic fatty acid are produced than in irrigation conditions. We conclude that freeze-dried avocado pulp shows slight changes in their nutritional quality.

La tecnología de liofilización es el mejor proceso de deshidratación para mantener mayor vida de anaquel y conservar las propiedades nutricionales y sensoriales de la pulpa del aguacate. El objetivo de este estudio fue determinar si el liofilizado y condición de producción tienen un efecto sobre la calidad nutrimental de la pulpa de aguacate cultivado en huertas de riego y temporal. Se aplicaron 4 tratamientos: frutos de temporal no liofilizado, frutos de riego no liofilizado, frutos liofilizados de temporal y frutos liofilizados de riego. Los resultados muestran que el fruto está compuesto por 71.39, 16 y 12.6% de pulpa, hueso y cascara respectivamente. La pulpa está compuesta por 71.51, 19.96, 2.81, 0.51 y 1.5 % de humedad, lípidos, cenizas, fibra cruda y proteína, respectivamente. El aceite del aguacate está constituido de 61. 18.8, 11.6 y 7% de ácidos grasos oleico, palmítico, linoléico y palmitoleico, respectivamente. El liofilizado disminuyó 1.43 g/100 g de ácido linoléico. Bajo condiciones de temporal se produce 4 y 13% menos grasa total y ácido graso oleico que en condiciones de riego. Se concluye que la pulpa del aguacate liofilizada presenta ligeros cambios en su calidad nutrimental.

The taxonomic identity of the symbiotic crabs Juxtafabia muliniarum sensu Cabrera-Peña et al. (2001) was revised. The morphology of these specimens, collected in the estuary of Punta Morales, Pacific coast of Costa Rica, in the oyster Saccostrea palmula did not agree with J. muliniarum but concurs well with topotypes and voucher material of Austinotheres angelicus from the Gulf of California, Mexico. Austinotheres angelicus belongs to the subfamily Pinnotherinae sensu Campos, 2009, and the morphology of A. angelicus supports its close relationship with Bonita mexicana and Enigmatheres canfieldi. The presence of a soft and thin carapace colored with deep chocolate brown with dark purple tones, a conspicuous protuberance in the basal antennal article, a third maxilliped with an ischio-merus fused with its inner margin angled, a carpus larger than the propodus, and a digitiform and small dactylus subdistally inserting on the ventral margin of the propodus are diagnostic features for A. angelicus. These characteristics separate this species from other pinnotherid crabs from the entire Pacific Ocean.

Se revisó la identidad taxonómica del cangrejo simbionte Juxtafabia muliniarum sensu Cabrera-Peña et al. (2001). La morfología de los especímenes recolectados en el estuario de Punta Morales, costa Pacífica de Costa Rica, en el ostión Saccostrea palmula no concordaron con J. muliniarum pero concurren bien con topotipos y material verificado de Austinotheres angelicus del Golfo de California, México. Austinotheres angelicus pertenece a la subfamilia Pinnotherinae sensu Campos, 2009 y su morfología apoya su cercana relación con Bonita mexicana y Enigmatheres canfieldi. La presencia de un caparazón blando y delgado, de color chocolate intenso con tonos purpura oscuros, una conspicua protuberancia en el artejo basal de la antena, un tercer maxilipedio con el isquio-merus fusionado con su margen interno angulado, un carpus más grande que el propodus y el pequeño dáctilo digitiforme que se inserta sobre el margen ventral del propodus son características diagnosticas para A. angelicus. Estas características separan a esta especie de otros pinotéridos del océano Pacífico.

Drought is a major constraint for common bean (Phaseolus vulgaris L.) production in México. Dehydrins are constitutive or stress-induced proteins related with a protective role of membranes and macromolecules against denaturation, thus preventing loss of their function. In this work, seed production and patterns of dehydrins accumulation in leaves and pods were evaluated in common bean cv. 'Otomí' subjected to drought, as compared with well-irrigated plants. Drought applied at pod formation and seed filling (SF) reduced yield up to 57 %. An antibody against a consensus sequence present in most dehydrins allowed for dehydrin identification. Two dehydrins of 82 and 73 kDA turned up both in leaves and pods throughout all the evaluated conditions. Presumably, both dehydrins are constitutive in the 'Otomí' cultivar. These dehydrins showed higher expression than controls in leaves after 6 d of drought at seedling and SF stages, and in pods 6 d after drought had started at SF. Increased expression might provide better protection during early stages of seedling and seed development. Increments on 63, 36 and 22 kDa dehydrin expression in pods at late SF might coincide with plant developmental programs, which prepare seed for desiccation. Dehydrins of 158, 54, 46, and 41 kDa were detected in pods 10 d after floral opening as a transient response to drought stress in SF. These results indicate dehydrins are relevant during plant development, as well as during drought stress.

La sequía es el factor más limitante de la productividad de frijol (Phaseolus vulgaris L.) en México. Las dehidrinas son proteínas constitutivas o inducibles por diferentes tipos de estrés, relacionadas con la protección a membranas y macromoléculas contra la desnaturalización, que evitan la pérdida de función. En este trabajo se estudió el efecto de la sequía aplicada en diferentes etapas de desarrollo, sobre la producción de semilla y los patrones de acumulación de dehidrinas en hojas y vainas de frijol cv. 'Otomí', comparado con plantas irrigadas. La sequía aplicada durante el período de formación de vainas y llenado de semilla (SF), redujo hasta 57 % el rendimiento. Las dehidrinas fueron identificadas con un anticuerpo que reconoce una secuencia consenso presente en la mayoría de ellas. Dehidrinas de 82 y 73 kDa fueron detectadas en hojas y en vainas en todas las condiciones evaluadas, por lo que se consideran constitutivas del cultivar 'Otomí'. Estas dehidrinas presentaron mayor expresión que el control en hojas a los 6 d de sequía aplicada en los estadios de plántula y SF, y en vainas también a los 6 d de sequía aplicada en SF. Estos incrementos podrían ser necesarios para brindar mejor protección en etapas tempranas del desarrollo de la plántula y la semilla. Incrementos en dehidrinas de 63, 36 y 22 kDa observados en vainas durante la etapa de SF, podrían ser parte del programa de desarrollo de la planta encargado de preparar a la semilla para la desecación. En vainas se detectaron dehidrinas de 158, 54, 46 y 41 kDa a los 10 d después de la apertura floral, como una respuesta transitoria al estrés hídrico en SF. Estos resultados indican que las dehidrinas de frijol son relevantes durante el desarrollo de la planta y durante condiciones de estrés por sequía.

A brief synopsis on the characteristics of decapod crustaceans and on recent classification proposals is presented. Through an exhaustive compilation of decapod crustacean records from Mexico, a species list was built for the continental, Caribbean, Gulf of Mexico and Pacific regions. A total of 1 775 species was obtained in 537 genera and 115 families. The Mexican decapod fauna represents 11.9% of the world's total. The most species rich families are Alpheidae (7.4%) and Palaemonidae (5.5%), while a total of 23 families have only one known species in Mexico. Out of the total number of species, 1 597 (89.9%) are marine and 178 freshwater (10.1%); in turn, 46.7% of the marine species occur in the Pacific , 31.4% in the Gulf of Mexico and 21.8% in the Caribbean, with an important proportion of species occurring in more than one of these regions. Due to the fact that the marine decapod fauna of Mexico is, in general, shared with neighboring countries levels of endemism are low. In contrast, there is a very high level of endemism in the freshwater fauna, considering for example freshwater crabs and crayfishes. Based on projections proposed by other authors it is estimated that we now know only half of the species of decapods that occur in Mexico.

Se presenta una breve sinopsis sobre las características de los crustáceos decápodos y sobre las propuestas recientes de su clasificación. Sobre la base de una compilación exhaustiva de los registros de crustáceos decápodos en México, se estableció un listado de estas especies para las regiones continental, del Caribe, del golfo de México y del Pacífico mexicano. En total se contabilizaron 1 775 especies distribuidas en 537 géneros y 115 familias. Se estima que la fauna de decápodos de México representa el 11.9% del total mundial. Las familias con mayor riqueza son Alpheidae (7.4%) y Palaemonidae (5.5%), mientras que un total de 23 familias cuentan con una sola especie conocida en México. Del total, 1 597 especies (89.9%) son marinas y 178 dulceacuícolas (10.1%); de las especies marinas 46.7% se encuentran en el Pacífico, 31.4% en el golfo de México y 21.8% en el Caribe, habiendo un número importante que se distribuye en más de una de estas regiones. Debido al hecho de que la fauna marina de crustáceos decápodos de México es, en general, compartida con algunos otros países vecinos, el nivel de endemismo es relativamente bajo. Por el contrario, en el caso de la fauna de aguas dulces, se observa un nivel de endemismo muy alto; por ejemplo, en los cangrejos de agua dulce y acociles. Basados en proyecciones de otros autores se estima que se conocen actualmente sólo la mitad de las especies de crustáceos decápodos que hay en México.

The apple snail Pomacea canaliculata (Lamarck, 1822) is for the first time reported for Mexico. The species was discovered in several locations adjacent to the Matamoros-1950 dam, Algodones, Baja California. The spread of P. canaliculata in Mexican waters was through the tributaries of the Colorado River from a population originally introduced in Yuma, Arizona, USA, around 2005. To date, no harmful effects have been detected on native vegetation, fauna of the Colorado River or agricultural crops in the Mexicali Valley, Baja California.

Se registra por primera vez para México el caracol manzano Pomacea canaliculata (Lamarck, 1822). La especie fue descubierta en varias localidades vecinas a la presa derivadora Matamoros-1950, Algodones, Baja California. La propagación de P. canaliculata en aguas mexicanas fue a través de los afluentes del río Colorado de la población inicialmente introducida en las vecindades de Yuma, Arizona, EUA en el 2005. Hasta el momento no han sido detectados efectos dañinos sobre los cultivos agrícolas del valle de Mexicali, sobre la vegetación o fauna nativa del río Colorado en el lado mexicano.

We documented the distributional status of 27 exotic fish species in the inland waters of the Baja California Peninsula, Mexico, based on voucher specimens collected from 122 sites between 1977 and 2010, and on published records. The species reported here are representatives of genera from the Atlantic drainages of North America (Ictalurus, Ameiurus, Pylodictis, Morone, Lepomis, Pomoxis, Dorosoma, Cyprinella, and Micropterus), Middle America (Poecilia, Gambusia, and Xiphophorus), Eurasia (Cyprinus and Carassius), and Africa (Tilapia and Oreochromis). The family containing the highest number of species is Centrarchidae (7 species) followed by Ictaluridae and Poeciliidae (6 species each). Four species were determined to be invasive due to their wide distribution and fast dispersal through the Peninsula (Gambusia affinis, Poecilia reticulata, Lepomis cyanellus, and Tilapia sp. cf. zillii). We analyze the impacts of exotic species on the native populations of 3 species with problems of conservation: Cyprinodon macularius (endangered), Fundulus lima (endangered), and Gasterosteus aculeatus (vulnerable). Alien fishes have been introduced for a variety of reasons in Mexico: ornament, sport, aquaculture, biological control, and by accident. In some cases fish introductions were carried out for more than one reason.

El estatus de la distribución de peces exóticos es documentado para 27 especies en las aguas continentales de la península de Baja California, México, basado en registros de ejemplares recolectados en 122 localidades durante el período de 1977 a 2010, así como registros referidos en la literatura. Las especies aquí reportadas son representativas de géneros que proceden de la vertiente Atlántica de Norteamérica (Ictalurus, Ameiurus, Pylodictis, Morone, Lepomis, Pomoxis, Dorosoma, Cyprinella y Micropterus), Mesoamérica (Poecilia, Gambusia y Xiphophorus), Eurasia (Cyprinus y Carassius) y África (Tilapia y Oreochromis). La familia con mayor número de especies es Centrarchidae (7 especies) seguida por Ictaluridae y Poeciliidae (con 6 especies cada una). Por su amplia distribución y rápida dispersión en la península, 4 especies son determinadas como invasivas (Gambusia affinis, Poecilia reticulata, Lepomis cyanellus y Tilapia sp. cf. zillii). Se analizan los impactos de las especies exóticas sobre las poblaciones nativas de 3 especies con problemas de conservación: Cyprinodon macularius (peligro de extinción), Fundulus lima (peligro de extinción) y Gasterosteus aculeatus (vulnerable). Las especies exóticas se han introducido en México por varias causas: ornamental, pesca deportiva, acuicultura, control biológico y la liberación intencionada. En algunos casos, las introducciones de peces se llevan a cabo por más de una causa.

A checklist of the free-living isopods of Todos los Santos Bay, Baja California, is presented on the basis of allochronic collections made between 1988 and 2005 along the rocky, sandy, and muddy intertidal and sandy subtidal to 256 meters deep. We collected 26 of the 48 species known from the Californian province: 2 Asellota; 7 Cymothoida; 1 Oniscoidea; 7 Sphaeromatidea; 9 Valvifera. The most abundant species were Excirolana linguifrons (Richardson, 1899), (sandy mesolitoral), Idotea fewkesi Richardson, 1905 and I. resecata Stimpson 1857, (rocky intertidal), Haliophasma geminatum Menzies and Barnard, 1959, (muddy intertidal and subtidal associated with the eel grass Zostera marina), and Caecognathia crenulatifrons (Monod, 1926) (sublitoral). All the recorded species were found in similar marine biotopes in California, USA. Of the 26 species, 7 are recorded for the first time in Mexico, extending their southern distribution to Todos los Santos Bay. These are: Erichsonella crenulata Menzies, 1950, Exosphaeroma amplicauda (Stimpson 1857), E. octonum (Richardson, 1899), Idarcturus allelomorphus Menzies y Barnard, 1959, I. fewkesi, Janiralata davisi Menzies, 1951 and Paracerceis gilliana (Richardson, 1899).

Se presenta una lista de los isópodos de vida libre de la bahía de Todos los Santos con base en recolecciones alocrónicas realizadas entre 1988 y 2005 en el intermareal rocoso, arenoso y limo-arcilloso así como en el sublitoral arenoso hasta una profundidad de 256 m. Se recolectaron 26 especies de las 48 registradas para la Provincia Californiana: 2 Asellota; 7 Cymothoida; 1 Oniscoidea; 7 Sphaeromatidea; 9 Valvifera Las especies más abundantes fueron Excirolana linguifrons (Richardson, 1899), (mesolitoral arenoso), Idotea fewkesi Richardson, 1905 junto con Idotea resecata Stimpson, 1857, (mesolitoral rocoso), Haliophasma geminatum Menzies et Barnard, 1959 (mesolitoral e infralitoral arcilloso asociada al pasto marino Zostera marina Linnaeus) y Caecognathia crenulatifrons (Monod, 1926), (sublitoral). Las especies recolectadas se ha registrado en biotopos marinos similares de California, Estados Unidos de América. De las 26 especies encontradas 7 son primeros registros para México: Erichsonella crenulata Menzies, 1950, Exosphaeroma amplicauda (Stimpson 1857), E. octonum (Richardson, 1899), Idarcturus allelomorphus Menzies et Barnard, 1959, Idotea fewkesi, Janiralata davisi Menzies, 1951 y Paracerceis gilliana (Richardson, 1899), extendiendo su distribución sureña hasta la bahía de Todos los Santos.