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Los peces de los llanos de Venezuela. Un ensayo sobre su historia natural.
Abstract and Figures
Este libro recopila y aporta nueva información acerca de las condiciones sobre la historia natural de algunas especies de peces que son comunes de la región de los llanos. También se discuten varias hipótesis del efecto de factores abióticos y bióticos sobre el origen y diversidad de especies en el Llano de Venezuela. Se plantean, por
otro lado, diversas problemáticas acerca del potencial pesquero y pesquerías en estas áreas, posibilidades del desarrollo piscícola y de conservación de la fauna silvestre; líneas de investigación y planes a desarrollar que permitirán obtener información básica y aplicada para la utilización y éxito de programas de manejo adecuado de los recursos naturales y pesqueros.
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... 3) Los órganos de contacto compuestos de crecimientos dérmicos u óseos blandos, como los odontodes hipertrofiados, o las espículas que se proyectan desde el margen de radio de aleta o escama, y están rodeados por la epidermis, a través de la cual pueden sobresalir los brotes óseos [58] (Figura 9). Muchos de ellos desaparecen después de la temporada de cría [59]. ...
... Estos podrían ser análogos a los dialectos locales de la vocalización o cantos de las aves y anfibios. También, podrían ser restricciones ecológicas tales como: a) la evolución filogenética de las sustancias de alarma químicas en los ostariofísinos; b) la alarma o sonido estridulante que producen los peces doradiodeos y calíctidos cuando son capturados por aves y reptiles, o son sacados del agua, donde ambos grupos se consideran principalmente presas; y/o, c) reconocimiento feromonal por comportamiento nupcial en especies migratorias y territoriales, esparcidas en el agua durante el comienzo de la temporada de lluvias, como los proquilodóntidos, algunos serrasálmidos y los grandes bagres pimelódidos [59,67,81,82]. Generalmente, se supone que los comportamientos comunicativos de los animales están genéticamente determinados y son comunes a todos los miembros de la misma especie. ...
... En algunos miembros de la familia Auchenipteridae también sirve para asir a la hembra y así lograr la fertilización interna. En peces como Hoplosternum littorale (Callichthyidae) los ruidos y el fuerte gancho que se forma en el extremo terminal de la aleta pectoral se pueden utilizar agresivamente para defender el nido flotante y posiblemente como un dispositivo engañoso para atraer a más hembras hacia éste, y así lograr un mayor número de huevos en su interior [59,60,83]. Algunos loricáridos como Acanthicus, Ancistrus, Hypostomus, Liposarcus y Pterigoplichthys, que hacen agujeros en las orillas del río, o bajo rocas y raíces de árboles sumergidas para anidar, también defienden el sitio por el ruido y las fuertes aletas pectorales y dorsales cubiertos por odontodes. ...
Exploro y reviso en detalle articulos sobre comunicación en peces, especialmente en un mundo oscuro como las aguas profundas de rios Neotropicales
... Venezuela (República Bolivariana de) posee entre 1 000 y 1 300 especies de peces de agua dulce (Lasso et al., 2004a,b;Lasso, Machado-Allison y Taphorn, 2016;Machado-Allison, 2005;Machado-Allison et al., 2010). De mil especies presentes en la cuenca del Orinoco más o menos 60 poseen importancia tanto en el aspecto comercial (pesquero) como en el de consumo de subsistencia en las poblaciones rurales e indígenas de la cuenca (Machado-Allison y Bottini, 2010) (Anexo 1). ...
... ej. el jimure (Montrichardia arborescens) y la carapa (Carapa guianensis)) (Novoa y Ramos, 1978;Novoa, 1982;Machado-Allison, 2005;Machado-Allison et al., 2010;Castro Lima, 2010;Hoyos, López y Fontiveros, 2012). ...
Según FishStatJ de FAO, las capturas de las pesquerías continentales de América Latina y el Caribe que se analizan en este documento alcanzaron 510 499 toneladas en 2019, lo que corresponde al 4 por ciento de la captura continental en el mundo. Sin embargo, la pesca continental de la región sufre de una subvaloración importante, y en base a la información recopilada estimamos un volumen de captura de por lo menos 850 000 toneladas para toda la región. La pesca continental en la región es normalmente de acceso abierto, ofreciendo oportunidades de empleo permanente u ocasional para alrededor de 1 millón de personas. Los pescadores integran un sector social marginado, de bajos recursos, frecuentemente sin tierra propia y con escaso acceso a servicios básicos. El pescado se comercializa casi siempre a través de intermediarios y sin agregarle valor, lo que reduce los beneficios económicos para los pescadores. Aunque el consumo de pescado en promedio en los países de la región es bajo existen comunidades rurales donde el consumo per cápita es varias veces mayor que el promedio mundial.
La presión pesquera en la región es muy inferior a la que se observa en los continentes de Asia y África, y se concentra principalmente en especies migratorias. En muchos ríos, las poblaciones de peces se encuentran todavía en un estado saludable con individuos de gran tamaño, considerándose que aún no se ha alcanzado el potencial pesquero y que existen todavía posibilidades de expansión aplicándose buenas prácticas de pesca. Sin embargo, los países de la región exhiben, por lo general, estructuras de manejo débiles, sin adecuados recursos humanos y económicos, y el manejo es de tipo verticalista y centralizado sin o con poca participación de los pescadores. Las pesquerías de la región enfrentan diversas amenazas, la mayoría de las cuales provienen del uso no sostenible de las cuencas más que de la extracción pesquera. Así, la construcción de embalses, la navegación, la desecación y aislamiento de humedales para la agricultura, la urbanización, la extracción de agua para riego, la contaminación urbana, industrial agrícola y minera son todos factores que pueden impactar directa o indirectamente sobre la calidad de la pesca y comprometer el bienestar de las comunidades pesqueras.
... Since 2020, Ivan Mikolji has been recognized as Associate Researcher of the Museo de Historia Natural La Salle, from the Fundación La Salle de Ciencias Naturales, in Caracas, Venezuela. (Fig. 7), along the floodplain of its main channel and in the drainages of the following rivers (or sub-basins): Atabapo, Inírida, Guaviare, Vichada, Bita, Meta, Tomo, Arauca, Apure, Caura, Morichal Largo and Delta, in Venezuela and Colombia (Fowler 1911;Novoa and Ramos 1978;Kullander 1981;Novoa et al. 1982;Román 1985;Novoa 1986;Román 1988;Winemiller 1989aWinemiller , b, 1990Lasso and Castroviejo 1992;Monente 1992;Machado-Allison 1993;Lasso et al. 1999;Mojica 1999;Ponte et al. 1999;Lasso and Machado-Allison 2000;Lasso et al. 2003aLasso et al. , b, c, 2004Campo 2004, Lasso 2004Machado-Allison 2003;Antonio and Lasso 2004;Taphorn et al. 2005;Galvis et al. 2007;Marcano et al. 2007;Lasso et al. 2009a, b;Brito et al. 2011;Lasso et al. 2011a, b;Echeverría and Machado-Allison 2015;DoNascimiento et al. 2017;Machado-Allison et al. 2018;Winemiller et al. 2018). It also occurs in the Gulf of Paria basin (Caño La Brea, Forest Reserve of Guarapiche, sub-basin San Juan River, EBRG 5055) in Venezuela . ...
... In its first stages of development, it is associated with floating vegetation and semi-rooted plants formed mainly in grasses and water hyacinth (Paspalum repens, Eichhornia crassipes). In the adult phase they are located in riparian zones, generally among grasses and sedges (Machado-Allison 1993;Lasso 2004;Lasso et al. 2011b;Echeverría and Machado-Allison 2015). Part of the type material was captured in the flooded savannah of a minor tributary of the Arauca River, in the floodplains of Apure State, Venezuela (Fig. 8b). ...
Based on morphological and molecular analysis of Astronotus species, a new species is described from the Orinoco River and Gulf of Paria basins in Venezuela and Colombia. Morphologically, it differs from As-tronotus crassipinnis and Astronotus ocellatus in pre-orbital depth, caudal peduncle depth, head width, and caudal peduncle length, with significant differences in average percentage values. Osteologically, it differs from the two described species by lacking a hypurapophysis on the parahypural bone (hypural complex) and having two or three supraneural bones. Another characteristic that helps diagnose the new species is the morphology of the sagitta otolith, which is oval with crenulated dorsal and ventral margins and a rounded posterior edge. Genetically, the new species is distinct from all the other lineages previously proposed for the genus, delimited by five single locus species delimitation methods, and also has unique diagnostic nucleotides. Phylogenetic analyses support the monophyly of the new species as well as all other species/lineages. Astronotus species have considerable genetic, anatomical, and sagitta otolith shape differences, but have few significant traditional morphometric and meristic differences, because there is high variability in counts of spines, soft dorsal-fin rays, and lateral-line scales. It is clear that this new species is genetically and anatomically differentiated from all other species within the genus, and deserves recognition as a new valid species. A peer-reviewed open-access journal Alfredo Perez et al. / ZooKeys 1113: 111-152 (2022) 112
... Con la presencia de lagunas inundables "préstamos" y marismas se amplían las posibilidades para las especies que habitan en estos nichos subyacentes al canal del río para establecer áreas útiles para el alevinaje como factor clave para el éxito reproductivo y de crecimiento de sus comunidades (MACHADO-ALLISON 2005). Se establecen algunos delineamientos para separar e identificar familias de peces dulceacuícolas y marino-estuarinas, basados en las descripciones existentes en la bibliografía, así como algunas observaciones sobre los ejemplares capturados en muestreos a lo largo del caño Mánamo. ...
... La identificación preliminar fue realizada utilizando una compilación de caracteres morfométricos de descripciones de familias de peces de agua dulce a través de los textos de NEIRA et al. (1998), NAKATAMI et al. (2001, SUTHERS & RISSIK (2009) y MACHADO-ALLISON (2005). Esto permitió contar con una clave preliminar que sirvió como patrón de separación taxonómica en larvas de peces de agua dulce y estuarinas, útil ante la ausencia de suficiente soporte teórico para tal fin (ver ANEXO I). ...
RESUMEN: Las condiciones ambientales extremas y variantes de las zonas estuarinas deltaicas determinan en mayor o menor grado la actividad reproductiva de la ictiofauna y la composición ictioplanctónica. En el delta del Orinoco, la determinación de zonas con presencia de huevos y larvas de peces permite un mejor manejo de estas áreas como reservorio en la conservación de la biodiversidad de las especies estuarinas. Se realizaron muestreos trimestrales del ensamblaje de larvas de peces con redes dobles para ictioplancton, de marzo de 2011 a febrero 2012, en 6 estaciones en los márgenes y canal central del caño Mánamo, ubicadas en los sectores superior, medio e inferior del delta del Orinoco. El material planctónico fue fijado en formaldehído al 4%, de donde se separaron los huevos y larvas de peces, se identificaron las especies y se les determinó la abundancia por sector. De las larvas aisladas se determinó entre los Clupeiformes la abundancia de larvas de la familia Clupeidae, Pristigasteridae y Engraulidae, así como de Scianidae entre otros. Dentro de los primeros se identificaron dos morfotipos de larvas clupeoides, capturadas en agua dulce del delta superior, separándose Pellona spp. por los pigmentos del margen inferior del pedúnculo caudal. Se observa un predominio de más de 60 % de larvas de Engraulidae sobre otros clupeidos, mientras que Pellona spp. se ubicó alrededor de 30%, y su mayor abundancia (280 larvas/m3) se encontró en las estaciones del delta inferior (Est. 5 y 6), y en menor frecuencia (3%) en el delta medio (Est. 3 y 4). La amplitud de la costa marina hacia las estaciones 5 y 6 permiten el intercambio con especies marino-estuarinas que dominan hacia estas áreas. Para los huevos de peces, la tendencia fue semejante, siendo mayor la presencia de huevos en las estaciones más salinas (19-28%o). Se nota una segregación más extrema en los huevos, donde las condiciones óptimas para el desove se presentarían en áreas salobres que ofrecen menor mortalidad larvaria por la menor diversidad de depredadores larvívoros en estos hábitats. La comprensión del papel de la localización de zonas de abundantes larvas podrá permitir un manejo más efectivo en la conservación de la biodiversidad de los recursos ícticos de la zona.
... Taxonomic studies on fish larvae are carried out in a scenario of great identification difficulties and scarce comparative literature, mainly in the neotropical region, the largest hotspot of fish diversity in continental waters in the world, with approximately 6.200 recognized species (Albert et al., 2020). However, work on describing the early stages of the fish life cycle has grown in this region (Machado-Allison et al., 2020;Nakatani et al., 2001;Orsi et al., 2016;Ponton & Mérigoux, 2001). In Brazil, studies of this nature they can be considered incipient, as they encompass approximately 4% of valid species, and are often incomplete and/or do not include details of the different stages of development Reynalte-Tataje et al., 2020;Zacardi, Santos, et al., 2020). ...
... While in the final stages of development, most of these individuals are colonizing water macrophyte stands Oliveira, Cajado, et al., 2020). In this way, intense pigmentation acts as camouflage while using structured environments (Machado-Allison et al., 2020;Santos et al., 2017). ...
Larvae and juveniles of long sardine, Triportheus auritus, from the lower Amazon river was described, evaluating ontogenetic changes in their external morphology, pigmentation, fin development, morphometry, and meristics. A total of 93 individuals, 83 larvae and 10 juveniles were analyzed, they were captured monthly between 2014 and 2019 in the Amazon river channel and in macrophytes aquatic stands in the alluvial plains located in the lower Amazon River. From each specimen, morphometric and meristic data were measured and then the growth pattern between morphometric variables was analyzed. The larvae have an elongated body in a fusiform shape, superior mouth, simple nostril, pigmented spherical eyes and long intestine, surpassing the median region of the body. Initial pigmentation is scarce, but intensifies through development forming a pattern composed of three longitudinal bands concentrated in the ventral, cephalo-dorsal and lateral line regions. There are also pigments in the mandible, surrounding the mouth, under the swim bladder, intestine and fins. The sequence of complete fin formation is: caudal, anal, dorsal, pectoral and pelvic. The total number of myomeres ranged from 45 to 48 (25–29 preanal and 17–22 postanal). Morphometric relationships indicated differential growth for measurable morphometric parameters, with abrupt growth of snout length, head length and body height in the transition from flexion to postflexion stages. The pre-dorsal distance showed a decrease in the growth rate at the threshold from the larval to the juvenile period. The pre-pectoral and pre-anal distances showed negative allometric growth. In conclusion, the combination of body shape pigmentation pattern and, the formation sequence of fins allow the identification of the genus and coupled with the number of myomeres, morphometric relationships, and ray numbers of the anal fin ensure the differentiation of T. auritus from the other congeneric species. The metamorphosis occurred mainly at the end of the larval period and it is related to changes in the physiological and ecomorphological characteristics of the species.
... Species such as: Pseudoplatystoma orinocoense, Pseudepapterus hasemani, Cichla orinocensis, Eigenmannia cf. limbata, Thoracocharax stellatus, Bunocephalus aloikae and Hoplosternum littorale, were associated with seasons with higher water temperature and low percentage of dissolved oxygen, where H. littorale is the clear example of species that develop physiological mechanisms of resistance (estivation and metabolic reduction) that guarantee their survival during periods of low rainfall (Machado-Allison and Zaret, 1984;Machado-Allison, 1986;Machado-Allison, De La Fuente, Mikolji, 2020). ...
The distribution and abundance of fish for the Orinoco River basin drainages are influenced by hydrometric seasonality and the structural complexity of the habitat, so understanding how fish assemblages are structured on a temporal and spatial scale is essential for biological conservation. Therefore, the purpose of this study was to describe the fish assemblage for the Mitimiti stream and test the hypothesis of spatial and temporal variation. To do this, collections were made at four sampling stations on the Mitimiti stream, during three contrasting rainfall seasons, with the help of a 10 m x 1.5 m trawl net and a 2 mm mesh eye. The diversity of fish assemblages was analyzed using Hill numbers, abundance-based dissimilarity, and a Canonical Correspondence Analysis (CCA). In total, 2493 individuals and 115 species were recorded, where the orders with the highest dominance were Characiformes and Blenniiformes. Regarding the diversity of order q = 0, no significant differences were found between the hydrological periods and the sampling stations, however, the low water period and St3 exhibited the highest species richness. The most dissimilar hydrological period was the high water season and the variables that significantly influenced fish assemblage were water temperature (p = 0.02) and dissolved oxygen (p = 0.05).
We evaluated the influence of hydrological phases and limnological variables on the taxonomic composition and functional diversity of fish associated with aquatic macrophytes in a floodplain lake of Amazon Basin, Brazil. Sampling was conducted using seine nets across the four phases of the local hydrological cycle (rising, high-water, receding, and low-water) during the year 2018 in Lake Maicá. The species were identified and classified into four functional groups on the basis of their ecological traits (migration, life history strategy, feeding habits, and swimming performance/microhabitat use). A total of 6075 individuals were captured, representing nine orders, 26 families, and 104 species. The fish assemblages underwent changes in both taxonomic and functional structure in response to the hydrological phases and limnological variables (pH, temperature, dissolved oxygen, and water transparency), with an increase in functional diversity during the receding water and low-water phase. During the low-water period, there was an increase in the abundance of fish with life history strategies at equilibrium, small periodic species as well as invertivores, piscivores, short-distance migrants, and residents. In contrast, the rising and high-water phases contributed to higher abundances of young fish (larvae and juveniles) and medium-distance migratory fish. The synergy among these factors acts as an environmental filter in the structure of the local ichthyofauna, allowing species with antagonistic ecological traits to coexist, maintain their populations, and reduce competition for space and food under varying environmental conditions during the four phases of the annual hydrological cycle. The information presented is essential for identifying priority areas for the conservation of fish assemblages, which represent the primary source of animal protein and income for the region, and for understanding the mechanisms responsible for changes in the taxonomic and functional structure of fish in Amazonian floodplain lakes.
The feeding habits of Moncholo Hoplias malabaricus (Bloch, 1794) in the cienaga de Ayapel, San Jorge River basin, Colombia, were studied. The stomach content was evaluated using the proportion of empty stomachs, grade of digestion, frequency of occurrence, numerical frequency and gravimetry. The trophic niche, equity index, welfare state, food preferences according to size and the hydrological cycle of the cienaga, the intestinal length-total length relationship and the relative importance index were also estimated. It was found that a large number of the stomachs studied were empty (73.6%) with only 10.8% of the food in a fresh state. Five items or food groups were identified in the diet: Fish, Vegetal matter, Insects, Detritus and Others. Fish was the most frequent group (94.6%), abundant (86.2%) and with the highest composition by weight (97.9%), both in the size structure and in the hydrological cycle of the cienaga, becoming the main food in the diet (IIR =92.6%), while the other groups had low relative importance. The food preferences suggest that the Moncholo is a stenophagous fish with carnivorous food habits and a piscivorous preference, which it maintains as it grows and with the level of the cienaga de Ayapel.
The initial development of the red‐bellied pacu Piaractus brachypomus is described using morphological, meristic and morphometric characteristics. A total of 127 individuals were analysed (47 in the yolk‐sac, 35 in pre‐flexion, five in flexion, 20 in post‐flexion and 20 in juvenile) with standard length varying between 2.92 and 48.61 mm. The larvae are born poorly developed and have a discoidal yolk at ~6.33 mm standard length. During early ontogeny, the mouth passes from terminal to subterminal and the anal opening reaches the vertical line over the midline region of the body. There are changes in body shape from long and moderate to deep, head length from small to large, and eye diameter from moderate to large. Dendritic chromatophores were present in the ventral, dorsal and upper part of the swim bladder in the early larval stages. Rounded spots are evident all over the body in juveniles. The total number of myomeres ranges from 39 to 41 (20–23 pre‐anal, 17–20 post‐anal). Through the morphometric relationships, it was evidenced that the greatest changes during the initial ontogeny of P. brachypomus occur in the transition from the post‐flexion stage to the juvenile period, indicating changes in behaviour, foraging and physiology.
The book WETLANDS: the vital network that connects us, deals with notions, ideas and didactic resources, to instruct on our connection with wetlands, and highlight the need to protect these environments by encouraging their valorization and empowerment based on sustainable use. It is a wide-ranging text written in informative and fresh language, to guide an entertaining learning, but without abandoning the scientific rigor and the exposition of updated information that this important topic deserves. Aimed at students, educators, community leaders, environmentalists and, in general, people who work in wetland science. It is divided into six chapters: Chapter 1 deals with the definition of wetlands, their differences with other aquatic systems, and their notable presence in Venezuela. Chapter 2 highlights the importance of wetlands as the core of evolutionary processes, production of biodiversity, food and water. Chapter 3 identifies the main threats facing wetlands. Chapter 4 presents guidelines and ideas for educational topics on wetlands. Chapter 5 summarizes aspects concerning the economic valorization of wetlands and Chapter 6 highlights cases of citizen empowerment and governance of wetlands.
RESUMEN
El libro HUMEDALES: la red vital que nos conecta, trata sobre nociones, ideas y recursos didácticos, para instruir sobre nuestra conexión con los humedales, y desta-car la necesidad de proteger esos ambientes alentando a su valorización y empode-ramiento con base en el aprovechamiento sustentable. Es un texto de amplio alcance escrito en lenguaje divulgativo y fresco, para guiar un aprendizaje entretenido, pero sin abandonar la rigurosidad científica y la exposición de información actualizada que este importante tema merece. Dirigido a estudiantes, educadores, líderes comunita-rios, ambientalistas y en general a personas que trabajen en la ciencia de los hume-dales. Está divido en seis capítulos: en el capítulo 1 se aborda la definición de los humedales, sus diferencias con otros sistemas acuáticos, y su notable presencia en Venezuela. En el capítulo 2 se destaca la importancia de los humedales como núcleo de procesos evolutivos, producción de biodiversidad, alimentos y agua. En el capítulo 3 se señalan las principales amenazas que confrontan los humedales. En el capítulo 4 se presentan lineamientos e ideas de temas educativos sobre los humedales. En el capítulo 5 se sintetizan aspectos concernientes a valorización económica de los humedales y en el capítulo 6 se subrayan casos de empoderamiento ciudadano y gobernanza de los humedales.
The genus Traverella (Insecta, Epeheroptera, Leptophlebidae) is reported for Venezuela. These insects were studied from substrate samples collected at the bottom of the Apure River; Its main characteristics are described and illustrations are presented about it. Additionally, the importance of these insects in the feeding of Gymnotiformes fish in this area of the Venezuelan plain is discussed.
RESUMEN
Se reporta para Venezuela el género Traverella (Insecta, Epeheroptera, Lepthophlebidae) Estos insectos se estudiaron a partir de muestras de sustrato colectadas en el fondo del río Apure; se describen sus principales características y se presentan ilustraciones sobre el mismo. Adicionalmente se discute sobre la importancia de estos insectos en la alimentación de los peces Gymnotiformes en esta área del llano venezolano
In this work, aspects of the wetlands of the Venezuelan plains are described, such as the demographic environment, vegetation, climatic features, relief, the dynamics of the mechanisms of operation of the flood process, the importance of these systems in the vital cycles of fish and projects that will potentially affect regional wetlands. This last topic acquires a special relevance, due to the fact that there are engineering projects that will potentially extensively modify the wetlands of the Venezuelan plains region, and, it could be said, will modify the dynamics of these ecosystems beyond our borders. The work is divided into eight chapters in which the general importance of these systems is described, and other specific topics such as the definitions of wetlands, their usefulness, the mechanisms of operation and the threats that hang over them, as well as as cases where the modification of the dynamics of wetlands has led to a series of ecological imbalances and conflicts of a social nature. At the end of the chapters, excerpts containing informative information are included, presented in boxes or special "boxes". One of these boxes highlights the impact that the closure of the Mánamo channel, in the Orinoco River delta, has had on the local ecological and social dynamics. In other boxes, examples of the importance that these systems have had in the main civilizations of the world over time, to support their agricultural and commercial development are presented; Their importance as replenishment stations for migratory birds is also highlighted. Likewise, these boxes address topics on ethnobotany, on the biology of some groups of fish in the great rivers that flood our plains savannahs, or the imminent danger in which the fish migration process finds itself today. from the llaneros rivers to the Andean foothills. It is hoped that in addition to making the technical aspects of the work less burdensome to read, these selected information boxes will show the reader the historical and pragmatic contexts of the management and importance of wetlands, beyond our borders and the purely scientific field. At the end of the work, a glossary is included, where some concepts of technical terminology, referring to wetlands, as well as words used in local jargon are explained.
RESUMEN
En este trabajo se describen aspectos sobre los humedales de los llanos venezolanos tales como el entorno demográfico, la vegetación, los rasgos climáticos, el relieve, la dinámica de los mecanismos de funcionamiento del proceso de inundación, la importancia de estos sistemas en los ciclos vitales de los peces y los proyectos que potencialmente, van a afectar los humedales regionales. Este último tópico adquiere una especial relevancia, debido a que existen proyectos de ingeniería que potencialmente van a modificar de manera extensiva los humedales de la región llanera venezolana, y, pudiera decirse, modificarán la dinámica de estos ecosistemas allende nuestras fronteras. El trabajo está dividido en ocho capítulos en cuyo desarrollo se describe la importancia general de estos sistemas, y otros temas específicos tales como las definiciones de humedales, la utilidad de éstos, los mecanismos de funcionamiento y las amenazas que se ciernen sobre los mismos, así como casos donde la modificación de la dinámica de los humedales, ha conllevado a una serie de desajustes ecológicos y conflictos de índole y social. Al culminar los capítulos se incluyen extractos que contienen información de tipo divulgativo, presentada en recuadros o “cajas” especiales. Se destaca, en uno de estos recuadros, el impacto que sobre la dinámica ecológica local, y sobre la dinámica social ha tenido el cierre del caño Mánamo, en el delta del río Orinoco. En otros recuadros, se presentan ejemplos de la importancia que estos sistemas han tenido en las principales civilizaciones del orbe a lo largo del tiempo, para apuntalar su desarrollo agrícola y comercial; también se destaca su importancia como estaciones de reabastecimiento de aves migratorias. Así mismo, se tocan en estos recuadros, tópicos sobre etnobotánica, sobre biología de algunos grupos de peces de los grandes ríos que inundan nuestras sabanas llaneras, o el inminente peligro en el que se encuentra en la actualidad, el proceso de migraciones de los peces desde los ríos llaneros hasta el piedemonte andino. Se espera que además de hacer menos pesada la lectura de los aspectos técnicos del trabajo, estos recuadros de información seleccionada muestren al lector los contextos históricos y pragmáticos del manejo y la importancia de los humedales, más allá de nuestras fronteras y del ámbito puramente científico. Al final del trabajo se incluye un glosario, donde se explican algunos conceptos de la terminología técnica, referidos a humedales, así como vocablos empleados en la jerga local.
A new species of catfish is described from the Esmeraldas River Basin, Pacific slope, northern Ecuador. Tentatively included in Microglanis, represents the second species of the genus inhabiting the Trans-Andean region. The new species is distinguished from known congeners by a unique combination of external characteristics: head and body color pattern, uniform, pale brown, yellowish or grayish, without any kind of blotches, bands or dots, only a lunate transverse band, dark or black, at caudal-fin origin; adipose-fin origin and forward without lighter or luminous areas. Compared with M. variegatus, the new species has morphometric differences, such as the distances between dorsal and pelvic fins, and between posterior nostrils. Some osteological characteristics are compared with those observed in species of Pseudopimelodidae inhabiting the Pacific versant of Colombia and Ecuador and with some other species of Microglanis.
The rivers at risk in Venezuela and the route for their conservation. Keywords: Biomonitoring, conservation, ecosystem management, hydrobiological resources.
El mapará Hypophthalmus marginatus es un bagre planctófago perteneciente a la familia Pimelodidae y es nativo de las cuencas más importantes de América del Sur. Uno de los requisitos esenciales para mantener el estoque pesquero y ampliar la oferta de especies cultivables es el estudio de los ciclos reproductivos en peces nativos, el cual contribuye significativamente al conocimiento biológico de las especies. El objetivo del presente estudio, pretende abordar de forma preliminar la caracterización del desarrollo oocitario de H. marginatus. Fueron analizadas las características histológicas de las gónadas de 17 hembras sexualmente maduras capturadas en el río Ariari (Puerto Rico, Meta), encontrando todos los tipos celulares del linaje germinativo, permitiendo establecer que es una especie del tipo asincrónico con desoves parciales.
A new species of whiptail armored catfish belonging to the genus Pseudohemiodon is described. The new species inhabits aquatic systems of the Orinoco River basin, mostly in the Llanos region of Colombia and Venezuela. Previously, it had identified as P. laticeps erroneously. The genus Pseudohemiodon includes seven known species inhabit Amazon and Paraná-Paraguay-Uruguay rivers basins. The new species is distinguished from congeners by the combination of the following characters: abdomen totally covered; area in front of gill opening without plates, ventrally; dorsal body color pattern without transversal dark bands, mostly in the caudal peduncle; head with straight sides; head and caudal peduncle narrower.
A new genus and species of whiptail loricariid catfish belonging to the Pseudohemiodon group is described with 12 specimens captured from the upper Orinoco River and Casiquiare River, Amazonas State, Venezuela. The specimens show delicate and fragile appearance, and are small (largest specimen 74.3 mm SL). The new species has external morphological characters that support its inclusion in the Pseudohemiodon group; however, its mouth morphology is distinctive and unique with features not observed in any species of that group, nor in any other species included in tribe Loricariini or in subfamily Loricariinae. The distinctive buccal characters include: 1) barblets on upper lip border and the maxillary barbel included and interconnected by translucent membrane, leaving the tips free; 2) lower lip surface covered with elongated, cylindrical, unbranched, and fleshy barblets, which resemble filaments, some of them surpassing the border of lower lip. The comparative analyses carried out determined that the recently described species Rhadinoloricaria papillosa has the same two diagnostic buccal characters observed in the new species; therefore it is transferred to the new genus.
The fish collection from the Museum of Escuela Politécnica Nacional, Quito, Ecuador, has nine lots with 12 specimens assigned to genus Rhadinoloricaria. Specimens come from the Napo and Pastaza rivers, Amazon River basin, eastern Ecuador. One specimen matches accurately with figures and original description of Loricaria macromystax Günther, 1869, type species of Rhadinoloricaria. After 150 years, this is the first secure identification of the species, which allowed an accurate description of the genus Rhadinoloricaria, and the discovery of a new species from Ecuador, described herein. In addition, using available specimens, figures and literature, a comparative analysis on external morphology was performed among the eight species included in Rhadinoloricaria. The analysis documented significant differences between them, in some morphological external characters and in buccal ornamentation. The results suggest that the eight species can be grouped into three or four genera. Rhadinoloricaria, in strict sense, has two species. Apistoloricaria is considered a valid genus, and include the four species previously assigned to it. Rhadinoloricaria bahuaja and R. rhami do not belong to the known genera in the Pseudohemiodon group. At this time, available data suggests that both species could continue included in ‘Rhadinoloricaria’, waiting further analyses to solve their generic status. Results support the use of buccal ornamentation patterns alone or combined with some morphological characters as valuable tool for generic identification within Loricariini.