Fishes of the Mitú Region: middle basin of the río Vaupés, Colombian Amazon / Peces de la región de Mitú: cuenca media del río Vaupés, Amazonia colombiana

Abstract: The Amazon River basin hosts the most diverse freshwater ichthyofauna in the world, and yet huge areas of the basin remain unexplored. This is the case for the upper tributaries of the rio Negro, especially those draining the Colombian territory. Here we present a list of 224 species derived from the examination of specimens collected in the Mitú region (Vaupés Department, Colombia), the middle basin of the río Vaupés. Of the species identified in our study, 10 species are recorded from Colombia for the first time, and 26 species are newly recorded from the Colombian Amazon. The number of species we present here comprise almost one-third of the known species diversity of the Colombian Amazon and nearly a tenth of the total number of those known across the entirety of the Amazon basin. The most diverse orders were Characiformes (120 species) and Siluriformes (65 species), and the remaining six orders comprised less than 20% of total species. The study area comprised blackwater systems, which are considered to be nutrient-poor environments. We discuss some ecological aspects that might explain how this highly diverse ichthyofauna originates and is maintain in less productive systems. The list presented here adds an important number of new records and complements the information derived from previous studies, carried out thus far with regards to the fish fauna of the Colombian Amazon.

Resumo: La cuenca del río Amazonas alberga la ictiofauna dulceacuícola más diversa del mundo, sin embargo, grandes áreas de la cuenca permanecen inexploradas. Este es el caso de los afluentes de la parte alta del río Negro, especialmente los sistemas que drenan el territorio colombiano. A continuación, presentamos un listado de 224 especies derivadas del análisis de especímenes recolectados en la región de Mitú, cuenca media del río Vaupés (Departamento de Vaupés, Colombia). De las especies identificadas, 10 especies se registran en Colombia por primera vez y 26 especies para la Amazonía colombiana. El número de especies que presentamos aquí comprende casi un tercio de las especies conocidas para la Amazonía colombiana y casi una décima parte del total de las conocidas para la gran cuenca del Amazonas. Los órdenes más diversos fueron Characiformes (120 especies) y Siluriformes (65 especies), y los seis órdenes restantes comprendieron menos del 20% del total de especies. El área de estudio comprende sistemas de aguas negras que se consideran ambientes poco productivos por sus bajos contenidos de nutrientes. Discutimos aquí algunos aspectos ecológicos que podrían explicar cómo esta ictiofauna tan diversa tiene su origen y es mantenida en estos sistemas poco productivos. La información derivada del presente estudio adiciona nuevos registros de especies de peces para Colombia, y complementa la información derivada de los estudios realizados a la fecha en la Amazonía colombiana.

Fishes from the Colombian Amazonia region: species composition from the river systems within the rainforest biome / Peces de la región de la Amazonía Colombiana: composición de especies de los sistemas fluviales del bioma de selva húmeda

Abstract The Colombian Amazon region is part of the Neotropical rainforest (humid forest biome) covering an area of 483,163 km2 and includes tributaries of both the Amazon and Orinoco River basins. The aquatic ecosystems found there include: rivers and alluvial plains originating in Andean headwaters, on eroded soils of tropical forests in the lowlands, and Guiana Shield formations, comprising a dense fluvial drainage network in the lowlands, with Paleogene/Neogene geological formations (terra firme streams in higher places that don't usually flood) and Paleozoic (shield streams); and Andean and Guiana Shield streams above 200-250 m a.s.l. We present here an exhaustive compilation of published information, supported by fish collections, consisting of a list of 1104 species distributed in 375 genera, 53 families, and 16 orders. We include occurrence data of these species in each sub-basin. The presence/absence species matrix was analyzed using a dendrogram and non-metric multidimensional scaling (NMDS) analysis to identify patterns of similarity between basins and sub-basins. We evaluated species composition between basins and among the different geological origins using PERMANOVA. The dendrogram shows co-occurrences of 404 species in the two basins. It also shows two clear groupings of the sub-basins of the Amazon (except Guainía-Negro drainages) and those of the Orinoco. Within the Amazon Basin, there are two nodes according to the geological origin: systems of Andean origin and those of the lowlands. The dendrogram results are consistent with the NMDS analysis, which shows a clear grouping according to the connectivity of the basins; the Guainía-Negro is included in the Amazon basin. Species distribution patterns were supported by the PERMANOVA, and differed significantly between basins (F = 4.3, R = 0.26, P = 0.003) and geological origin (F = 3.6, R = 0.23, P = 0.003). The number of species in this study represents almost a fifth of the ichthyofauna of the Neotropics and about a third of that of the Amazon River basin; clearly supporting Colombia's status among the countries with the greatest diversity of freshwater fish species of the planet. We include here a significant number of new records (75 spp), provide a first approximation of the distribution patterns, and a framework for future biogeographical studies.

Resumo La región de la Amazonía colombiana hace parte del bosque húmero neotropical (bioma de selva húmeda) abarcando un área de 483.163 km2 e incluye afluentes de las cuencas del Amazonas y Orinoco. Los ecosistemas acuáticos encontrados allí incluyen: ríos y llanuras aluviales, originándose en cabeceras andinas, en suelos erosionados de bosques tropicales en tierras bajas y en formaciones de escudos; conformando una densa red fluvial en tierras bajas con formaciones geológicas paleógenas-neógenas (arroyos de terra firme en sitios elevados que usualmente no se inundan) y paleozoicas (arroyos de escudo); y arroyos andinos y del escudo Guayanés por encima de 200-250 m s.n.m. Presentamos aquí una recopilación exhaustiva de información publicada, sustentada por colecciones ictiológicas, consistiendo en una lista de 1104 especies distribuidas en 375 géneros, 53 familias y 16 órdenes. Incluimos datos de estas especies en cada subcuenca. La matriz de presencia/ausencia de especies fue analizada usando un dendrograma y un análisis de escalamiento multidimensional no métrico (NMDS) para identificar patrones de similitud entre cuencas y subcuencas. Se evaluó la composición de especies entre cuencas y entre los diferentes orígenes geológicos usando PERMANOVA. El dendrograma refleja coocurrencia de 404 especies en las dos cuencas. También muestra dos agrupaciones claras de las subcuencas del Amazonas (excepto Guainía-Negro) y las del Orinoco. Dentro de la cuenca amazónica existen dos nodos según el origen geológico: los sistemas de origen andino y los de tierras bajas. Los resultados del dendrograma son consistentes con el análisis NMDS, el cual muestra una clara agrupación según la conectividad de las cuencas; el Guainía-Negro está incluido en la cuenca del Amazonas. Los patrones de distribución de especies fueron respaldados por el PERMANOVA y difirieron significativamente entre cuencas (F = 4.3, R = 0.26, P = 0.003) y origen geológico (F = 3.6, R = 0.23, P = 0.003). El número de especies en este estudio representa casi la quinta parte de la ictiofauna del Neotrópico y alrededor de un tercio de la de la cuenca del río Amazonas; soportando el estatus de Colombia entre los países con mayor diversidad de especies de peces de agua dulce del planeta. Incluimos aquí un número importante de nuevos registros (75 spp), brindamos una aproximación de los patrones de distribución y un marco para futuros estudios biogeográficos.

Local environmental factors influence beta-diversity patterns of tropical fish assemblages more than spatial factors.

A major goal in ecology is to understand mechanisms that influence patterns of biodiversity and community assembly at various spatial and temporal scales. Understanding how community composition is created and maintained also is critical for natural resource management and biological conservation. In this study, we investigated environmental and spatial factors influencing beta diversity of local fish assemblages along the longitudinal gradient of a nearly pristine Neotropical river in the Colombian Llanos. Standardized surveys were conducted during the low-water season at 34 sites within the Bita River Basin. Physical, chemical, and landscape parameters were recorded at each site, and asymmetric eigenvector maps were used as spatial variables. To examine the relative influence of dispersal and environmental variables on beta diversity and its components, distance-based redundancy analysis (db-RDA) and variation partitioning analysis were conducted. We proposed that spatial scale of analysis and position within the river network would constrain patterns of beta diversity in different ways. However, results indicated that in this system, high beta diversity was consistent among species assemblages no matter the scale of analysis or position within the river network. Species replacement (turnover) dominated beta diversity, an indication of the importance of species sorting. These findings suggested that conservation of fish diversity in tropical rivers requires maintenance of both habitat heterogeneity (spatial variation in habitat conditions) and connectivity at the scale of entire river basins.

A new species of Pimelodella Eigenmann amp; Eigenmann, 1888 (Siluriformes: Heptapteridae) from the Sierra Nevada de Santa Marta, Colombia.

A new species of Pimelodella is described from northern coastal drainages of the Sierra Nevada de Santa Marta (SNSM), Colombia. The new species is diagnosed from all trans-Andean congeners by the following unique combination of characters: head length 22.2-23.7% SL, bony interorbital width 17.6-21.6% HL, maxillary barbels length 53.0-68.3% SL, inner mental-barbels length 14.4-20.0% SL, body width 17.6-21.1% SL, dorsal-fin spine length 8.3-13.7% SL, dorsal-fin base 12.3-14.9% SL, pectoral-fin spine length 12.9-14.5% SL, pectoral-fin spine length without dentations on the distal posterior margin 21.6-29.8% in pectoral-fin spine length, maximum depth of dentations in posterior margin of pectoral-fin spine 1.40-1.68 times in the width of the spine at its base, adipose-fin base length 22.8-26.4% SL, caudal-peduncle depth 9.2-10.5% SL, 40 vertebrae, having a conspicuous paired dark brown stripe on the dorsal surface of body, extending from posterior margin of head to caudal-fin insertion and a wide dark brown midlateral stripe present. The isolated occurrence of this new taxon living in allopatry in coastal drainages of the SNSM could have interesting biogeographic implications for dispersal and vicariance processes of the ichthyofauna from northern South America.

A new species of Creagrutus (Characidae: Stevardiinae) from the upper Río Magdalena, Colombia.

A new species of Creagrutus is described from several localities in the upper Río Magdalena drainage, Colombia. Creagrutus dulima n. sp. differs from all trans-Andean congeners by the combination of a relatively small orbital diameter, the shape and position of hooks on the pelvic-fin rays, in having the third infraorbital not in contact with the preopercle ventrally, and the presence of a dark, reticulated pigmentation pattern on the dorsal portion of body. The distribution of Creagrutus species in the Magdalena-Cauca River Basin is discussed, and an updated identification key for species of trans-Andean Creagrutus is provided.

Checklist of the freshwater fishes of Colombia: a Darwin Core alternative to the updating problem.

The present work is part of a process to create a Catalogue of the Freshwater Fishes of Colombia and consisted in the depuration and updating of the taxonomic and geographic components of the checklist of the freshwater fishes of Colombia. An exhaustive revision of the 1435 species recorded in 2008 was necessary to: 1. Add new species described since 2009 and species originally described from Colombia but inadvertently omitted in 2008; 2. Add new records of already described species; 3. Delete species whose presence in Colombia was not supported by voucher specimens in ichthyological collections; and 4. Revise the geographic distribution of the species listed in 2008. This process resulted in the following numbers: 1. Total number of freshwater fish species in Colombia: 1494; 2. Number of species recorded by hydrographic region - Amazon: 706, Orinoco: 663, Caribbean: 223, Magdalena-Cauca: 220, Pacific: 130; and 3. Number of endemic species: 374 (76% from the trans-Andean region). Updating the current checklist is a fundamental requirement to ensure its incorporation in the decision-making process with regard to the conservation of Colombian aquatic species and ecosystems, which are facing transformation processes as a result of activities such as mining, construction of hydroelectric plants, expansion of the agricultural frontier and subsequent deforestation, industrial and domestic pollution, development of waterways, introduction of exotic species, and climate change.

ResumenEl presente trabajo es parte de un proceso para crear un Catálogo de Peces de Agua Dulce de Colombia y consistió en la depuración y actualización de los componentes taxonómico y geográfico del listado de peces de agua dulce de Colombia. Una revisión exhaustiva de las 1435 especies registradas en 2008 fue necesaria para: 1. Adicionar las especies nuevas descritas desde 2009 y especies descritas originalmente para Colombia pero omitidas inadvertidamente en 2008; 2. Adicionar nuevos registros de especies ya descritas; 3. Eliminar especies cuya presencia en Colombia no estaba soportada por especímenes en colecciones ictiológicas; y 4. Revisar la distribución geográfica de las especies listadas en 2008. Este proceso resultó en las siguientes cifras: 1. Número total de especies de peces de agua dulce en Colombia: 1494; 2. Número de especies registradas por región hidrográfica - Amazonas: 706, Orinoco: 663, Caribe: 223, Magdalena-Cauca: 220, Pacífico: 130; y 3. Número de especies endémicas 374 (76% distribuidas en la región transandina). La actualización del presente listado es un requerimiento fundamental para asegurar su incorporación en el proceso de toma de decisiones en lo concerniente a la conservación de las especies y ecosistemas acuáticos colombianos, los cuales están enfrentando procesos de transformación, como resultado de actividades como la minería, construcción de plantas hidroeléctricas, expansión de la frontera agropecuaria y subsecuente desforestación, polución industrial y doméstica, desarrollo de hidrovías, introducción de especies exóticas y cambio climático.

Ecomorphological relationships of fish assemblages in a trans-Andean drainage, Upper Magdalena River Basin, Colombia

Ecomorphological patterns of the fish community were evaluated in the trans-Andean Alvarado River drainage, Colombia. A total of 29 species using 25 ecomorphological indices were analyzed to test how well the ecomorphological patterns are related to the fish assemblage. Although a significant correlation was found (Mantel test) between morphological attributes and trophic guilds, habitat use and distribution across the altitudinal gradient, only the last two were significantly independent of the phylogenetic relationships (partial Mantel test). Regarding the ecomorphological space, two main trends were defined. First, benthic periphytivores and invertivores were characterized by having dorsal or dorsolateral eyes, labial appendages, depressed bodies and well-developed pectoral, ventral and caudal fins, which provide them the ability to stabilize over the substrate and make rapid movements. Second, nektonic detritivore-invertivores and insectivores were found to have laterally compressed bodies, lateral eyes and larger eyes and anal fins. These species use vision during predation, are good continuous swimmers and possess higher maneuverability and stability. These results show that the fish assemblages in the Alvarado River drainage are structured ecomorphologically mainly by habitat and the altitudinal gradient. Therefore, this is evidence of the importance of habitat structure to maintain the functionality of the ecosystem.(AU)

Se evaluaron los patrones ecomorfológicos de la comunidad íctica en la cuenca transandina del Río Alvarado, Colombia. Se analizaron 29 especies empleando 25 índices ecomorfológicos con el fin de evaluar los patrones ecomorfológicos con el ensamblaje de peces. A pesar de que se encontró una correlación significativa (Prueba de Mantel) de los atributos morfológicos con los gremios tróficos, preferencia de hábitat y la distribución de las especies a lo largo del gradiente altitudinal, solamente las dos últimas fueron independientes de la filogenia (Prueba parcial de Mantel). Con relación al espacio ecomorfológico dos patrones fueron identificados. Primero, las especies bentónicas perifitívoras e invertívoras, caracterizadas por ojos dorsales o dorsolaterales, cuerpos deprimidos y aletas desarrolladas, proporcionando la capacidad de estabilizarse sobre el sustrato y realizar movimientos rápidos. Segundo, especies nectónicas detritívoras-invertivoras e insectívoras con cuerpos comprimidos, ojos laterales y mayor área relativa de ojos y aleta anal; estos usan la visión durante la actividad predatoria, con mayor capacidad de maniobrabilidad y estabilización. Estos resultados muestran que el ensamblaje de peces en la cuenca está estructurado principalmente por el uso de hábitat y el gradiente altitudinal, esto podría ser evidencia de la importancia de la estructura del hábitat para garantizar la funcionalidad del ecosistema.(AU)

A new species of Trichomycterus (Siluriformes: Trichomycteridae) from the upper río Magdalena basin, Colombia.

Trichomycterus tetuanensis, new species, is described from the río Tetuan, upper río Magdalena basin in Colombia. The new species is distinguished by its margin of caudal fin conspicuously emarginate, in combination with a high number of opercular odontodes (21-39), reflected externally in the large size of the opercular patch of odontodes, 3 irregular rows of conic teeth in the upper jaw, 42-52 interopercular odontodes, 8 branchiostegal rays, 37 post Weberian vertebrae, 7 branched pectoral-fin rays, hypural 3 separated from hypural plate 4+5, and background coloration light brown with darker dots uniformly sparse on dorsum and sides of trunk. Some apomorphic characters informative for the phylogenetic affinities of the new species within Trichomycterus are discussed.

Variation in freshwater fish assemblages along a regional elevation gradient in the northern Andes, Colombia.

Studies on elevation diversity gradients have covered a large number of taxa and regions throughout the world; however, studies of freshwater fish are scarce and restricted to examining their changes along a specific gradient. These studies have reported a monotonic decrease in species richness with increasing elevation, but ignore the high taxonomic differentiation of each headwater assemblage that may generate high ß-diversity among them. Here, we analyzed how fish assemblages vary with elevation among regional elevation bands, and how these changes are related to four environmental clines and to changes in the distribution, habitat use, and the morphology of fish species. Using a standardized field sampling technique, we assessed three different diversity and two structural assemblage measures across six regional elevation bands located in the northern Andes (Colombia). Each species was assigned to a functional group based on its body shape, habitat use, morphological, and/or behavioral adaptations. Additionally, at each sampling site, we measured four environmental variables. Our analyses showed: (1) After a monotonic decrease in species richness, we detected an increase in richness in the upper part of the gradient; (2) diversity patterns vary depending on the diversity measure used; (3) diversity patterns can be attributed to changes in species distribution and in the richness and proportions of functional groups along the regional elevation gradient; and (4) diversity patterns and changes in functional groups are highly correlated with variations in environmental variables, which also vary with elevation. These results suggest a novel pattern of variation in species richness with elevation: Species richness increases at the headwaters of the northern Andes owing to the cumulative number of endemic species there. This highlights the need for large-scale studies and has important implications for the aquatic conservation of the region.

Diversidad y distribución de mariposas Satyrinae (Lepidoptera: Nymphalidae) en la cuenca del río Coello, Colombia

Diversity and distribution of Satyrinae butterflies (Lepidoptera: Nymphalidae) in the Coello river basin, Colombia. We describe the patterns of diversity and distribution of the subfamily Satyrinae in the Coello river basin (4º 17’ 08’’ N - 74º 35’ 36’’ W; 1 899.31 km²) from 433 to 3 600 m. Eleven sampling stations were located, in several ecosystems. The samples were collected during a period of 11 days, in March, May, July and October 2003, in three types of habitat (forest, forest edge and meadow). We collected at random, between 09:00 and 15:00 hr, using entomological nets. A total of 239 individuals (13 genera, 34 species) were collected. The most abundant species were in the genus Pedaliodes (41.4 %). Richness and diversity had high values in mountainous zones and paramo (> 2 000 m). The greater diversity was measured in the forest edge. The similarity analysis produced two groups: species from warm (Euptychia hesione and Hermeuptychia hermes) and middle (Pseudohaetera hypaesia and Taygetis celia) climate zones; and species from mountain and paramo (Lymanopoda obsoleta, Pedaliodes polusca and Eretris calisto). Rev. Biol. Trop. 55 (2): 645-653. Epub 2007 June, 29.

Este estudio describe los patrones de diversidad y distribución de la subfamilia Satyrinae en la cuenca del río Coello (4º 17’ 08’’ N y 74º 35´ 36" W; 1 899.31 km²), en un gradiente altitudinal de 433 a 3 600 m.s.n.m, con el fin de determinar la diversidad y composición regional y local de este grupo de mariposas y su posible uso como indicador biológico de zonas montanas y de Páramo. Se establecieron 11 estaciones de muestreo las cuales incluyen distintas zonas de vida. Las muestras se recolecciónron durante un periodo de 11 días en marzo, mayo, julio y octubre de 2003, en tres tipos de hábitat (bosque, borde de bosque y pradera). La recolección fue al azar en transectos de longitud no definida, entre las 09:00 y las 15:00 hr, empleando para ello redes lepidopterológicas de 0.5 m de diámetro y 1.20 m de longitud. Para el análisis de datos se calculó el índice de riqueza de Margalef (D) y se registró el porcentaje de abundancia relativa para las especies. La diversidad total por localidad y por hábitat se analizó a través del índice de Shannon (H’). De las matrices de presencia-ausencia se obtuvo índices de similitud entre estaciones, según coeficiente de Jaccard. Se recolectó un total de 239 individuos de 13 géneros y 34 especies. Las especies más abundantes fueron especialmente del género Pedaliodes, representando el 41.4%. La riqueza y diversidad, presentaron un comportamiento similar, mostrando altos valores en zonas montanas y de Páramo (> 2000 m.s.n.m). En cuanto a la diversidad por hábitat, se observó la mayor diversidad en el borde de bosque. El análisis de similitud evidenció dos grupos claramente definidos. El primer grupo contempla especies propias de zonas cálidas (Euptychia hesione y Hermeuptychia hermes) y templadas (Pseudohaetera hypaesia y Taygetis celia), mientras el segundo presenta especies exclusivas de zonas montanas y de Páramo (Lymanopoda obsoleta, Pedaliodes polusca y Eretris calisto).

[Diversity and distribution of Satyrinae butterflies (Lepidoptera: Nymphalidae) in the Coello river basin, Colombia]. / Diversidad y distribución de mariposas Satyrinae (Lepidoptera: Nymphalidae) en la cuenca del río Coello, Colombia.

We describe the patterns of diversity and distribution of the subfamily Satyrinae in the Coello river basin (4 degrees 17' 08" N - 74 degrees 35' 36" W; 1,899.31 km2) from 433 to 3,600 m. Eleven sampling stations were located, in several ecosystems. The samples were collected during a period of 11 days, in March, May, July and October 2003, in three types of habitat (forest, forest edge and meadow). We collected at random, between 09:00 and 15:00 hr, using entomological nets. A total of 239 individuals (13 genera, 34 species) were collected. The most abundant species were in the genus Pedaliodes (41.4 %). Richness and diversity had high values in mountainous zones and paramo (> 2,000 m). The greater diversity was measured in the forest edge. The similarity analysis produced two groups: species from warm (Euptychia hesione and Hermeuptychia hermes) and middle (Pseudohaetera hypaesia and Taygetis celia) climate zones; and species from mountain and paramo (Lymanopoda obsoleta, Pedaliodes polusca and Eretris calisto).