Knowledge about the diversity of coastal amphipods in the eastern tropical Pacific, including the Pacific coast of Colombia, is scarce. We characterized amphipod diversity in Bahía Málaga (intertidal and subtidal rocky shores, and sandy beaches) and Bahía Buenaventura (intertidal rocky shores, mangrove roots, and sandy beaches), two important estuaries in the central Pacific coast of Colombia. Sixteen species in eleven families were found; Hourstonius baciroa, Leptocheirus rhizophorae, Leucothoe alata, Elasmopus ocoroni, Melita bousfieldi, and Neomegamphopus heardi represent new records for Colombia.

El conocimiento acerca de la diversidad de los anfípodos costeros en el Pacífico Oriental Tropical, incluyendo las costas del Pacífico de Colombia, es escaso. Por esto, caracterizamos la diversidad de anfípodos en Bahía Málaga (costas rocosas intermareales y submareales, playas arenosas) y Bahía Buenaventura (costa rocosa intermareal, raíces de manglares, playas arenosas), dos estuarios importantes de la costa central del Pacífico de Colombia. Se encontraron 16 especies en once familias, de las cuales Hourstonius baciroa, Leptocheirus rhizophorae, Leucothoe alata, Elasmopus ocoroni, Melita bousfieldi y Neomegamphopus heardi representan nuevos registros para Colombia.

RESUMEN Los peces criptobentónicos contribuyen de manera significativa a la dinámica trófica de los ecosistemas costeros. Este estudio tuvo como objetivo determinar la composición de esta comunidad y comprobar si su estructura difiere temporal y espacialmente en el Parque Nacional Natural Uramba Bahía Málaga (Pacífico Oriental Tropical). Los peces se recolectaron utilizando sustratos artificiales en tres zonas, entre junio de 2008 y agosto de 2009. Se registraron 26 especies, pertenecientes a 11 familias. Gobiidae y Labrisomidae fueron las familias más representativas (especies: 34,6 % e individuos: 66 %). La riqueza y abundancia aumentó en un gradiente del interior hacia el exterior del parque. Utilizando estadística multivariada, se identificó un patrón espacial en la estructura de la comunidad, con localidades internas significativamente diferentes de las medias y externas. Cerdale ionthas, Gobiosoma seminudum, Starksia fulva y Gobulus hancocki fueron responsables de esta diferenciación (contribución > 59 %). El uso de sustratos artificiales para tomar muestras de peces criptobentónicos demostró ser una forma eficiente de identificar una parte de la ictiofauna que no había sido identificada mediante técnicas de muestreo tradicionales y también fue útil para comparar la variabilidad espacial de esta comunidad. La comparación con comunidades de peces criptobentónicos en otras regiones biogeográficas indica que, debido a la baja riqueza de especies en el Pacífico Oriental Tropical, estas comunidades tanto en Colombia como en México muestran baja redundancia funcional y considerables diferencias en sus preferencias tróficas.

ABSTRACT Cryptobenthic fishes contribute significantly to the trophic dynamics of coastal ecosystems. This study aimed at determining the composition of this assemblage and testing if its structure differs temporally and spatially in the Uramba National Natural Park Bahía Málaga (Tropical Eastern Pacific). Fish assemblages were collected using artificial traps in three zones, between June 2008 and August 2009. Twenty-six fish species belonging 11 families were recorded. Gobiidae and Labrisomidae were the most representative families (species: 34.6 % and individuals: 66 %). Species richness and abundance increased in a gradient from the interior to the exterior of the park. Using multivariate statistic techniques, a spatial pattern in assemblage structure was identified with inner zone being significantly different from the mid and outer zones. Cerdale ionthans, Gobiosoma seminudum, Starksia fulva, and Gobulus hancocki were mainly responsible for this differentiation (> 59 % contribution). The use of artificial habitats to sample cryptobenthic fish proved to be an efficient way to identify an overlooked part ichthyofauna using traditional sampling techniques and was also useful to compare the spatial variability of these assemblages. Comparisons with cryptobenthic fish assemblages in other biogeographic regions indicate that, due to their low species richness in the Tropical Eastern Pacific, these assemblages in both Colombia and Mexico show low functional redundancy and considerable differences in their predominant trophic modes.

O presente estudo descreve duas novas espécies de crustáceos decápodos da infauna baseado em material coletado na Bahía Málaga, costa pacífica da Colombia, em 2009. A primeira delas, o corrupto Axianassa darrylfelderi sp. nov. (Axianassidae), aparenta estar mais relacionada morfologicamente a A. australis Rodrigues & Shimizu, 1992, A. canalis Kensley & Heard, 1990, e A. jamaicensis Kensley & Heard, 1990. Contudo, a nova espécie difere em uma combinação de caracteres morfológicos, principalmente no exópodo uropodial, acículo (escama) antenal, terceiro maxilípede e primeiro pleonito. A segunda espécie nova, o camarão Leptalpheus canterakintzi sp. nov. (Alpheidae), associado às galerias de A. darrylfelderi sp. nov., incontestavelmente representa a espécie-irmã no Pacífico Oriental da espécie L. axianassae Dworschak & Coelho, 1999 do Atlântico Ocidental, a qual vive exclusivamente em galerias de A. australis. As duas espécies são distinguíveis apenas pelas proporções do mero e propodo do terceiro par de pereiópodos. Além disso, Leptalpheus azuero Anker, 2011, previamente conhecido somente para o Panamá, é registrado pela primeira vez para a Colômbia.

Two new species of infaunal decapod crustaceans are described based on material collected in Bahía Málaga, Pacific coast of Colombia, in 2009. The mud-shrimp Axianassa darrylfelderi sp. nov. (Axianassidae) appears to be most closely related to A. australis Rodrigues & Shimizu, 1992, A. canalis Kensley & Heard, 1990, and A. jamaicensis Kensley & Heard, 1990. The new species may be distinguished from each of them by a combination of morphological features, mainly on the uropodal exopod, antennal acicle, third maxilliped and first pleonite. The shrimp Leptalpheus canterakintzi sp. nov. (Alpheidae), associated with burrows of A. darrylfelderi sp. nov., undoubtedly represents the eastern Pacific sister species of the western Atlantic L. axianassae Dworschak & Coelho, 1999, which lives exclusively in burrows of A. australis. The two species are reliably distinguishable only by the proportions of the merus and propodus of the third pereiopod. Leptalpheus azuero Anker, 2011, previously known only from the Pacific coast of Panama, is reported for the first time from Bahía Málaga, Colombia.