Resumo En regiones tropicales hay una gran cantidad de especies de diatomeas que todavía no han sido identificadas. Esta investigación tuvo como objetivo estudiar la composición de la flora de diatomeas epilíticas encontradas en muestras recolectadas en el río Dagua, una cuenca hidrográfica andina tropical, ubicada suroeste de Colombia. Los muestreos se realizaron en tres estaciones con sus respectivas tres réplicas entre enero y abril de 2018 para recolectar muestras para la identificación de diatomeas (Clase Bacillariophyceae). Estas muestras se analizaron con microscopía óptica y microscopía de contraste interferencial. Los resultados indicaron la presencia de 18 taxa distribuidos en 9 familias y 11 géneros. Dos de estas, son nuevos registros para Colombia: Navicula incarum y Fragilaria aff. socia. El género con mayor riqueza específica fue Navicula. Una comparación con la flora de diatomeas de la región muestra que se registraron nueve especies en común con el Río Cali.

Abstract In tropical regions there are a large number of species of diatoms that have not been identified yet. This research aimed to study the composition of epilithic diatom flora found in samples collected in Dagua River a tropical Andean hydrographical basin located to the southwest of Colombia. Samplings were performed in three stations with their respective three replicas between January and April 2018 to collect samples for identification of diatom (Class Bacillariophyceae). These samples were analyzed with light microscopy and interferential contrast microscopy. The results indicated the occurrence of 18 taxa distributed in 9 families and 11 genera. Two of these are new records for Colombia: Navicula incarum and Fragilaria aff. socia. The most species-rich genera was Navicula. A comparison with the diatom flora of the region shows that 9 species were recorded in common with the Cali River.

ABSTRACT Background: The Angulo River has been subject to environmental deterioration as a result of agriculture practices and industrial discharges to its tributary. Goal: Determine the species of diatoms that indicate contamination and their distribution in the Angulo river, a tributary of the Lerma river. Method: Twelve sites including 2 springs were selected during the low-water and post-rain periods of 2005. The samples were obtained by scraping the rocks to separate the attached diatoms. These were cleaned by oxidizing the sample with hydrochloric acid and hydrogen peroxide; permanent preparations were made with Naphrax® resin, for review with light microscopy. Results: 50 taxa belonging to 20 genera were identified, of which 5 species belong to central forms and 45 to pennate species. The taxa present in both periods were Achnanthidium minutissimum, Amphora pediculus, Luticola geoppertiana, Nitzschia amphibia, Nitzschia dissipata var. dissipata, Pleurosira laevis, Staurosira pinnata and Ulnaria ulna. The temperature, pH, dissolved oxygen and total dissolved solids in the Angulo river presented spatial variations and with it the species records. Conclusions: Representative taxa of eutrophic and non-eutrophic environments were found throughout the tributary, such as Nitzschia palea and Amphora pediculus, respectively. This study has provided relevant information regarding the presence and distribution of diatom species that can be used as bioindicators of environmental conditions. specific.

RESUMEN Antecedentes: El río Ángulo ha estado expuesto a un deterioro ambiental como consecuencia de las descargas industriales a su afluente. Objetivo: Determinar las especies de diatomeas indicadoras de contaminación y su distribución en el río Angulo afluente del río Lerma. Métodos: Se seleccionaron 12 sitios incluyendo 2 manantiales durante los periodos de estiaje y post lluvias del año 2005. Las muestras se obtuvieron raspando las rocas para separar las diatomeas adheridas. Estas se limpiaron oxidando la muestra con ácido clorhídrico y peróxido de hidrógeno; se elaboraron preparaciones permanentes con la resina Naphrax®, para su revisión con microscopia óptica. Resultados: Se identificaron 50 taxones pertenecientes a 20 géneros de los cuales 5 especies pertenecen a formas centrales y 45 a las pennadas. Los taxones espresentes en ambos periodos fueron Achnanthidium minutissimum, Amphora pediculus, Luticola geoppertiana, Nitzschia amphibia, Nitzschia dissipata var. dissipata, Pleurosira laevis, Staurosira pinnata y Ulnaria ulna. La temperatura, pH, oxígeno disuelto y sólidos disueltos totales en el río Angulo presentaron variaciones espaciales y con ello los registros de las especies. Conclusiones: A lo largo del afluente, se encontraron taxones representativos de ambientes eutrofizados y no eutrofizados como Nitzschia palea y Amphora pediculus. Este estudio aporta información relevante en cuanto a la presencia y distribución de especies de diatomeas que pueden ser utilizadas como bioindicadores de condiciones ambientes específicos.

The dryland ecosystems in the world comprise about 40% of the earth terrestrial surface where the biological soil crusts (BSCs) are a major colonizers. Collections of the soil crusts were carried out at the coastal lomas of Pachacamac and Iguanil at the central Peruvian coastal desert in South America. Aeroterrestrial communities were typified as epilitics and edaphics with their morphospecies characterization of the streptophyte Klebsormidium.The species K. fluitans, K. flaccidum and K. crenulatum are first reports for the Peruvian microalgal flora and increase their distribution and similitud to other biogeographic regions of our biosphere. They showed phenotypic plasticity with transitional morphotypes and reproductive strategies (aplanospores, fragmentation) for dispersion and propagation as desiccation stress responses.

Los ecosistemas áridos del mundo abarcan aproximadamente el 40% de la superficie terrestre parte del cual es colonizado por las costras biológicas del suelo. Las colecciones de costras biológicas se realizaron en las lomas costeras de Pachacamac e Iguanil del desierto Peruano costero central en Sudamérica. Ellas fueron tipificadas como comunidades aereoterrestres epilíticas y edáficas con la caracterización de las morfoespecies de la estreptofita del género Klebsormidum. Las especies K. fluitans, K. flaccidum y K. crenulatum son primeros reportes para nuestra flora microalgal que extienden su distribución y similitud a otras regiones biogeográficas de nuestra biosfera. Las especies exhibieron plasticidad fenotípica reconocido por los morfotipos transicionales y estrategias reproductivas (aplanosporas, fragmentación) para su dispersión y propagación en respuesta a las condiciones de estrés por desecación.

Background and Aims: The diatom Craticula gadorensis sp. nov. is described from samples of epilithic algae collected in a shallow pond from the Gador mountains, in the province of Almería (Spain). M: Samples were taken and processed following the usual protocols for diatoms. Morphological and ultrastructural characteristics of this new taxon are described and illustrated using light and scanning electron microscopy. Results: The new species is characterised by having elliptic-lanceolate to rhombic-lanceolate valves, with slightly protracted, subrostrate apices, a linear, narrow axial area and a slightly dilated, linear-lanceolate central area. Conclusions: A morphological comparison with related species shows that the combination of features in Craticula gadorensis is unique (mainly the dimensions, areola density and the shape of the central area).

Introducción y objetivos: Se describe la diatomea Craticula gadorensis sp. nov. a partir de muestras de algas epilíticas recogidas en una balsa ganadera de la Sierra de Gádor, en la provincia de Almería. M: Las muestras se tomaron y procesaron siguiendo los protocolos metodológicos para diatomeas. Los caracteres morfológicos y ultraestructurales de este nuevo taxón se describen e ilustran mediante imágenes de microscopía óptica y electrónica. resultados: La nueva especie se caracteriza por presentar valvas elíptico-lanceoladas a rómbico-lanceoladas, con ápices ligeramente prolongados, subrostrados, con un área axial lineal, estrecha y un área central un poco dilatada, lineal-lanceolada. conclusiones: La comparación morfológica con otras especies del género muestra que la combinación de caracteres de Craticula gadorensis (principalmente las dimensiones, la densidad de areolas y la forma del área central) es única.

Resumo A presente pesquisa objetivou o estudo da composição da flora de diatomáceas epilíticas encontradas em amostras coletadas na bacia hidrográfica do Rio Cali, Colômbia. Excursões trimestrais (março, junho, setembro e dezembro de 2012 e março de 2013) foram realizadas em seis sítios de amostragem para coletar amostras para a identificação dos organismos do grupo das diatomáceas (Classe Bacillariophyceae). Os resultados indicaram a ocorrência de 83 táxons, distribuídos em 26 famílias e 38 gêneros. 32 desses táxons são novas ocorrências na Colômbia. As famílias mais representativas foram Gomphonemataceae, Naviculaceae e Bacillariaceae. Os gêneros com maior riqueza de espécies foram Navicula, Gomphonema e Nitzschia. Oito espécies tiveram ocorrência em todos os sítios de amostragem: Achnanthidium minutissimum, Cocconeis lineata, Cymbella affinis, Gomphonema pumilum var. rigidum, Melosira varians, Navicula symmetrica, Reimeria sinuata e Rhoicosphenia abbreviata. Os resultados indicaram 13 espécies consideradas dominantes, e caracterizam a flora diatomológica da bacia hidrográfica do Rio Cali, Colômbia.

Abstract This research aimed to study the composition of epilithic diatom flora found in samples collected in Cali River hydrographical basin, Colombia. Quarterly excursions (March, June, September and December of 2012 and March of 2013) were performed in six sampling sites to collect samples for identification of diatom organisms (Class Bacillariophyceae). The results indicated the occurrence of 82 taxa distributed in 26 families and 38 genera. 32 of these are new occurrences in Colombia. The most representative families were Gomphonemataceae, Naviculaceae and Bacillariaceae. The genera richest in species were Navicula, Gomphonema and Nitzschia. Eight species occurred in all sampling sites: Achnanthidium minutissimum, Cocconeis lineata, Cymbella affinis, Gomphonema pumilum var. rigidum, Melosira varians, Navicula symmetrica, Reimeria sinuata and Rhoicosphenia abbreviata. The results indicated 13 species considered dominant and characterize the flora of epilithic diatoms in Cali River hydrographical basin, Colombia.

Abstract Background Most studies on benthic diatoms found in northwestern Mexico have been done along the western coast of the Baja California peninsula. Thus, few studies exist for the Gulf of California. Goals To gather new records of benthic diatoms found in the Gulf of California. Methods Diatom samples from sediments and rocks of the coast of Santa Rosalía, Baja California Sur, were observed under a light microscope (LM). Results Three taxa were recorded and depicted: Caloneis liber var. bicuneata (common), Gyrosigma naja (scarce), and the new combination Entomoneis pulchra var. pulchella (scarce). Conclusions These three taxa were recorded for the first time in northwestern Mexico.

Resumen Antecedentes Los estudios sobre diatomeas bentónicas para el Noroeste mexicano se han hecho principalmente para la costa occidental de la península de Baja California, pero son pocos para el golfo de California. Objetivos Presentar nuevos registros de diatomeas bentónicas para el golfo de California. Métodos Se observaron muestras de diatomeas de sedimentos y rocas de la costa de Santa Rosalía, Baja California Sur, México bajo el microscopio de luz. Resultados Se registraron tres nuevos taxa: Caloneis liber var. bicuneata (común) y Gyrosigma naja (raro), y la nueva combinación Entomoneis pulchra var. pulchella (raro). Conclusiones Estos tres taxa son registrados por primera vez para la región Noroeste de México.

Abstract: The epilithic algae and cyanoprokaryotes that inhabit the Archaeological Zone of Yaxchilán, Chiapas, cover most of the walls of buildings; it is a site located in the Lacandon Jungle, next to the Usumacinta river with a very high relative humidity. The aim of this work was to document the species of algae and cyanoprokaryotes that grow on the archaeological monuments of this area, based on the microscopic morphology. From 135 samples collected between 2006 and 2008, 49 species were identified: 25 Chroococcales, 12 Nostocales and 3 Oscillatoriales of Cyanoprokaryota; 3 Chlorellales and 4 Trentepohliales of Chlorophyta and 2 Naviculales of Bacillariophyta. We describe 9 species that are new records for Mexico and all the species found are illustrated as a reference. The ecological valence of the species allows to characterize the flora with affinity to a karst substrate with a basic pH and under fluctuating light, humidity and temperature conditions during the day. Finally, the need to preserve flora and monuments following control strategies based on knowledge of the life cycles of epilithic organisms is pointed out. This is the first study on algae and cyanoprokaryotes in the archaeological zone of Yaxchilán.

Resumen: Las algas y cianoprocariontes epilíticas que habitan en la Zona Arqueológica de Yaxchilán, Chiapas, cubren la mayoría de los muros de los edificios; es un sitio que se encuentra en la Selva Lacandona, junto al río Usumacinta con una humedad relativa muy alta. El objetivo de este trabajo fue documentar las especies de algas y cianoprocariontes que crecen sobre los monumentos arqueológicos de esta zona, con base en la morfología microscópica. De 135 muestras recolectadas entre 2006 y 2008, se identificaron 49 especies: 25 Chroococcales, 12 Nostocales y 3 Oscillatoriales de Cyanoprokaryota; 3 Chlorellales y 4 Trentepohliales de Chlorophyta y 2 Naviculales de Bacillariophyta. Se describen 9 especies que son nuevos registros para México y todas las especies encontradas son ilustradas como referencia. La valencia ecológica de las especies permite caracterizar la flora con afinidad a un sustrato calcáreo con un pH básico y en condiciones de iluminación, humedad y temperatura fluctuantes durante el día. Finalmente, se señala la necesidad de conservar la flora y los monumentos siguiendo estrategias de control basadas en el conocimiento de los ciclos de vida de los organismos epilíticos. Este es el primer estudio sobre las algas y cianoprocariontes de la zona arqueológica de Yaxchilán.

Abstract: The knowledge of the continental algae from Mexico is far to be complete. The taxonomic records currently reach 3 256 species, but many of them lack a description, an illustration or both, as well as information about their ecology or economic potential. Studies contributing to the knowledge of Mexican species come mainly from the states of Michoacan, Mexico, Puebla, Oaxaca, and Mexico City; the rest of the country is practically unexplored. Such is the case of Nuevo Leon, where until 2011 its 21 records represented scarcely 0.64% of nation diversity. This lack of information about a potentially important resource motivated the gathering of algal records and prospecting of different water bodies in the center of the state, in order to determine the species of algae. To make it, historical reports of genera and species up to 2015 were compiled and the information was complemented by transect sampling of benthos in 30 stations in the period 2014-2016. The results represent a relative increase of 324% on previous phycologycal knowledge and are presented as a taxonomic list for the state, which consists of 68 species distributed in 51 genera and 37 families. Most of the species are epilithic or planthonic and have a cosmopolitan distribution.

Resumen: El conocimiento de las algas continentales de México es aún deficiente. Los registros taxonómicos suman actualmente 3 256 especies, pero muchos de ellos carecen de una descripción, una ilustración o de ambas, además de información ecológica o de su potencial económico. Los estudios que contribuyen a esta cifra sobre la riqueza específica nacional provienen principalmente de los estados de Michoacán, Ciudad de México, Estado de México, Puebla y Oaxaca, el resto del país está prácticamente inexplorado. Tal es el caso del estado de Nuevo León, donde hasta el 2011 sus 21 registros representaban apenas un 0.64% de la riqueza del país. El desconocimiento de este recurso, potencialmente importante, motivó realizar una prospección en distintos cuerpos de agua del centro del estado, con la finalidad de determinar las especies presentes y con ello, elaborar una lista de especies actualizada. Para este fin se compilaron los reportes históricos de géneros y especies hasta el 2015 y se realizaron muestreos bénticos por medio de transectos en 30 estaciones en el periodo de 2014-2016. Los resultados representan un aumento relativo sobre el conocimiento ficológico previo de un 324% y se presentan como un listado taxonómico para el estado, el cual ahora consta de 68 especies distribuidas en 51 géneros y 37 familias. La mayoría de las especies son epilíticas o planctónicas y tienen una distribución cosmopolita.

Resumo Objetivo: O objetivo deste estudo foi avaliar os aspectos taxonômicos e a distribuição geográfica das desmídias perifíticas de dois substratos diferentes na zona litorânea de um lago artificial urbano. Métodos Amostras de desmídias epífitas e epilíticas foram coletadas por raspagem de gramíneas e rochas, respectivamente, em duas estações no lago municipal de Cascavel, Paraná, durante abril de 2015 e março de 2016 e 2017. No laboratório, os táxons obtidos a partir das amostras foram fotografados e suas características morfométricas foram registradas. A composição das espécies de desmídias foi caracterizada e a frequência de ocorrência, bem como a distribuição geográfica de cada táxon no Estado do Paraná foram registradas. Resultados Nós identificados 35 táxons, distribuídos em 10 gêneros. Os gêneros mais representativos foram Closterium Nitzsch ex Ralfs e Cosmarium Corda ex Ralfs. Uma alta ocorrência de táxons esporádicos (60%) foi observada, e entre os táxons registrados, os mais frequentes foram Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum e Desmidium grevillei (Kützing ex Ralfs) De Bary. Nove táxons foram exclusivos para o substrato epilítico e somente Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus foi exclusivo para o substrato epifítico, enquanto os demais 25 táxons ocorreram em ambos os substratos. Sete táxons são novas ocorrências para o estado do Paraná. Conclusão Embora nossos resultados sejam de natureza qualitativa, eles fornecem uma base de dados sobre a distribuição biogeográfica dos táxons, os quais são cruciais para futuros estudos taxonômicos e ecológicos que podem contribuir para a preservação da biodiversidade.

Abstract Aim: The aim of this study was to assess the taxonomic aspects and geographical distribution of the periphytic desmids from two different substrates in the littoral zone of an urban artificial lake. Methods Samples of epiphytic and epilithic desmids were collected by grass and rock scraping, respectively, in two stations in the Cascavel municipal lake, Paraná, during April 2015, and March 2016 and 2017. In the laboratory, the taxa obtained from the samples were photographed and their morphometric characteristics recorded. The species composition of the desmid was characterized, and the frequency of occurrence as well as the geographic distribution of each taxon in the Paraná State were recorded. Results We identified 35 taxa, distributed in 10 genera. The most representative were Closterium Nitzsch ex Ralfs and Cosmarium Corda ex Ralfs. A high occurrence of sporadic taxa (60%) was observed and among the recorded taxa, the most frequent were Cosmarium pseudoconnatum Nordstedt var. pseudoconnatum and Desmidium grevillei (Kützing ex Ralfs) De Bary. Nine taxa were exclusive to the epilithic substrate and only Netrium digitus (Ralfs) Itzigsohn & Rothe var. digitus was exclusive to the epiphytic substrate, while the remaining 25 taxa occurred in both substrates. Seven taxa are new records for the Paraná State. Conclusion Although our results are of qualitative nature, they provide baseline data on the biogeographic distribution of taxa, which are crucial for future taxonomic and ecological studies that might contribute to the preservation of the biodiversity.

Resumo: Objetivo Este estudo objetivou conhecer a variação sazonal das diatomáceas epilíticas ao logo do Rio Gravataí em relação a composição e densidade, assim como a respectiva relação com variáveis limnológicas locais. Métodos As diatomáceas foram amostradas trimestralmente utilizando o amostrador EDS exposto por quatro semanas, no período de setembro de 2000 a agosto de 2002. A área de 75 cm2 de material foi raspado de três rochas submersas totalizando uma amostra composta. Alíquota de 1 ml de material oxidado foi montado em lâminas para análise qualitativa e quantitativa. Resultados Um gradiente espacial de contaminação orgânica foi observada no rio Gravataí devido à diminuição do oxigênio dissolvido e aumento do DBO5, nitrogênio total e orto-fosfato do curso superior para o inferior, e a predominância de condições eutróficas durante períodos de maior temperatura (primavera e verão). As diatomáceas epilíticas exibiram em seu curso superior um padrão sazonal em abundância, as mais altas densidades foram registradas no outono e inverno, o aumento da densidade esteve associada as médias e baixas temperaturas, mais baixa turbidez e disponibilidade de nutrientes. Bacillariacea foi dominante na primavera, Eunotiaceae e Bacillariaceae no verão e outono e Gomphonemataceae foi fortemente dominante seguido de Eunotiaceae no inverno. No curso inferior Bacillariaceae foi dominante em todas as estações do ano exceto no outono de 2001. Essas mudanças foram determinadas pela substituição na ocorrência e relativa abundância de algumas espécies como Achnanthidium minutissimum, Cocconeis placentula, Eunotia bilunaris, Frustulia saxonica, Gomphonema parvulum, Nitzchia palea e Sellaphora seminulum. Conclusões A sazonalidade das diatomáceas foi bem evidenciada no trecho superior do rio, entretanto no curso inferior com maior impacto antrópico, poucas mudanças ocorrem no número de espécies e/ou substituição de algumas espécies por outras, mostrando que a sazonalidade das diatomáceas pode ser afetada pela contaminação orgânica e eutrofização.

Abstract: Aim This study aimed to understand the seasonal variation of epilithic diatoms in the Gravataí River regarding their composition and density along the river, as well as the respective relationships with local limnological variables. Methods The diatoms were sampled quarterly using a EDS sampler exposed for four weeks from September 2000 to August 2002. An area of 75 cm2 was scraped off the upper surface of three submerged stones totalizing a composed sample. An aliquot of 1 ml of oxidized material was mounted on a slide for the quantitative and qualitative analysis. Results A spacial organic contamination gradient was observed in the Gravataí river due the decrease of dissolved oxygen, and increase of BOD5, total nitrogen and ortho-phosphate from the upper to the lower course and the predominance of eutrophic conditions during periods of higher temperature (spring and summer). The epilithic diatoms presented, in the upper stretch, a seasonal pattern in abundance with the highest densities during the fall and winter, the density enhance was associated to mild and low temperatures, lowest turbidity and nutrients availability. Bacillariaceae was dominant in the spring, Eunotiaceae and Bacillariaceae in the summer and fall and Gomphonemathaceae was strongly dominant followed by Eunotiaceae in winter. In the lower course Bacillariaceae was dominant in all seasons except on fall 2001. These changes were determined by the substitutions in the occurrence and relative abundance of some species as Achnanthidium minutissimum, Cocconeis placentula, Eunotia bilunaris, Frustulia saxonica, Gomphonema parvulum, Nitzchia palea and Sellaphora seminulum. Conclusions The seasonality of the diatoms was well evidenced in upper stretch of the river, therefore in the lower course with greater anthropogenic impact, fewer changes occurs in the number of species present and/or of substitution of some species by others, showing that the seasonality of the diatoms can be affected by organic contamination and eutrophication.

Abstract: Background: The Zinapécuaro River basin has a high level of pollution coming from different economic activities that take place in the area, which have caused noticeable environmental damage. Unfortunately, there are no studies of the water quality of this river and thus we have no information regarding what current pollutants are present or their emitting sources. Goals: We studied the epilithic diatom community of the headwaters of the Zinapécuaro River, Michoacán, Mexico. Methods: Samples were collected at four stages during a one-year period. Results: Seventy species pertaining to the classes Coscinodiscophyceae, Fragilariophyceae, and Bacillariophyceae were identified. The latter had 62 taxa. The species found at all of the sampling sites were Achnanthidium exiguum, A. minutissimum, Encyonema silesiacum, Eolimna subminuscula, Frustulia latita, F. neomundana, Gomphonema lagenula, Navicula rhynchocephala, Nitzschia clausii, N. palea, Planothidium frequentissimum, P. lanceolatum, and Rhopalodia brebisonii. Among the species found at the sites, the ones with the highest degree of eutrophication are Navicula germainii, N. recens, N. rhynchocephala, Nitzchia clausii, N. palea, N. inconspicua, and Planothidium lanceolatum. Conclusions: Using nonparametric estimators, we found that observed species richness represented 80.5 to 89.7% of the expected richness. Rarefaction analysis indicated that the sampling effort was enough to represent the species richness in the study area and at the selected sites, except at a spring and at the Yerbabuena River during the rainy season (2013), and the Yerbabuena spring during the dry season (2013), where a greater number of samples would be needed. The greatest diversity, estimated with the Shannon-Wiener index, was found at Las Orquídeas during the rainy season of 2013. Seasonal analysis using ANOSIM showed no statistically significant differences (p >0.05), whereas Bray-Curtis similarity values did show statistically significant differences. Spatial and temporal distribution differences were associated with the differences in depth, nitrites, ammonium, pH, and total water hardness.

Resumen: Antecedentes: La cuenca del río Zinapécuaro presenta un alto grado de contaminación proveniente de diversas actividades económicas que se desarrollan en la zona, situación que ha generado un marcado deterioro ambiental. Desafortunadamente no existen estudios de la calidad del agua en este río y se desconoce el tipo de contaminantes presentes y las fuentes emisoras. Objetivos: Estudiar la comunidad de diatomeas epilíticas de la cabecera del río Zinapécuaro, Michoacán, México. Métodos: La recolecta se llevó a cabo durante un ciclo anual y se realizaron cuatro muestreos. Resultados: Fueron identificadas 70 especies pertenecientes a las clases Coscinodiscophyceae, Fragilariophyceae y Bacillariophyceae, esta última fue representada con 62 taxones. Las especies comunes en todos los sitios fueron Achnanthidium exiguum, A. minutissimum, Encyonema silesiacum, Eolimna subminuscula, Frustulia latita, F. neomundana, Gomphonema lagenula, Navicula rhynchocephala, Nitzschia clausii, N. palea, Planothidium frequentissimum, P. lanceolatum y Rhopalodia brebisonii. Las especies presentes en sitios con mayor grado de eutrofización fueron Navicula germainii, N. recens, N. rhynchocephala, Nitzchia clausii, N. palea, N. inconspicua y Planothidium lanceolatum. Conclusiones: Mediante estimadores no paramétricos se encontró que la riqueza específica obtenida fue de 80.5 a 89.7% de la riqueza esperada. El análisis de rarefacción indicó que el esfuerzo de muestreo para representar la riqueza del área de estudio y los sitios seleccionados fue suficiente, excepto para el manantial y el río Yerbabuena en la época de lluvias (2013) y el manantial de la Yerbabuena en la época de estiaje (2013), en los que se requeriría un tamaño de muestra más grande. La mayor diversidad, estimada con el índice Shannon-Wiener, se presentó en Las Orquídeas (época de lluvias 2013). El análisis por temporadas mediante ANOSIM no mostró diferencia estadística significativa en similitud (p >0.05) entre ellas; mientras que para sitios/temporadas sí hubo diferencias en los valores de similitud de Bray-Curtis. Las diferencias de distribución a nivel temporal y espacial se asociaron a diferencias en profundidad, nitritos, amonio, pH y dureza total.

ABSTRACT: The application and development of environmental laws governing watershed management requires identification of biological indicators, parameters and measures to establish its ecological status, for which the present study aims to characterize the ecological indicator value of stream benthic algae in an urban area of Mexico City. Six sites of the Magdalena river were studied in the most contrasting seasons: dry-warm, rainy and dry-cold. At each site the physicochemical parameters of water were recorded and 10 samples were collected: Five with visible algal growths and five with diatoms. The environmental quality of each site was determined by the trophic status and its confirmation with the richness and benthic algal diversity, through a canonical correspondence analysis and the calculation of the indicator value of species (IndVal). According to the trophic status, three groups of sites were recognized. The first group (G1) was assessed as reference of the oligotrophic conditions and presented 11 species with the highest IndVal, protruding: Encyonema silesiacum, Gomphonema parvulum, Navicula cryptocephala, Planothidium lanceolatum, Vaucheria bursata, Placoma regulare and Nostocparmelioides. A second group (G2) was associated with 15 species considered detectors, which were tolerant to increased nutrients in at least one season, such as Diatoma mesodon and Prasiola mexicana. The third group (G3) included sites with species that had a wide range of tolerance to pollution: Fistulifera saprophila, Nitzschia minuta, Nitzschia palea, Nitzschia recta and Phormidium autumnale. The species IndVal of Magdalena River has established reference sites of good environmental quality and those that are altered by human activities, therefore they are recommended as the first step in a methodological proposal for a long-term biomonitoring through a biological index.

RESUMEN: La aplicación y desarrollo de las leyes ambientales que regulan el manejo de cuencas requiere la identificación de indicadores biológicos, los parámetros y las medidas para establecer su estado ecológico, para lo cual el presente estudio tiene como objetivo caracterizar el valor indicador ecológico de las algas bentónicas en una corriente urbana de la Ciudad de México. Se estudiaron seis sitios del río Magdalena en las estaciones más contrastantes del año: seca cálida, lluviosa y seca fría. En cada sitio se registraron los parámetros fisicoquímicos del agua y se recolectaron 10 muestras: cinco con crecimientos algales visibles y cinco con diatomeas. La calidad ambiental de cada sitio fue determinada por el estado trófico y su confirmación con la riqueza y diversidad algal bentónica, a través de un análisis de correspondencia canónica y del cálculo del valor indicador de las especies (IndVal). De acuerdo con el estado trófico se reconocieron tres grupos de sitios. El primer grupo (G1) fue valorado como de referencia de condiciones oligotróficas y presentó 11 especies con el mayor IndVal, sobresaliendo: Encyonema silesiacum, Gomphonema parvulum, Navícula cryptocephala, Planothidium lanceolatum, Vaucheria bursata, Placoma regulare y Nostoc parmelioides. Un segundo grupo (G2) se relacionó con 15 especies consideradas como detectoras, las cuales fueron tolerantes al incremento de nutrientes en al menos una época del año, tales como Diatoma mesodon y Prasiola mexicana. El tercer grupo (G3) incluyó sitios con especies que presentaron una amplia tolerancia a la contaminación: Fistulifera saprophila, Nitzschia minuta, Nitzschia palea, Nitzschia recta y Phormidium autumnale. El IndVal de las especies del río Magdalena ha permitido establecer los sitios de referencia de buena calidad ambiental y los que aparecen alterados por las actividades humanas, por lo que se recomiendan como el primer paso de una propuesta metodológica que permita el biomonitoreo a largo plazo a través de un índice biológico.

El presente trabajo se llevó a cabo en el marco del proyecto para elaborar un índice de calidad biológica para ríos de zonas bajas y de piedemonte del país basado en comunidades biológicas acuáticas, desarrollado en el Laboratorio de Biotecnología del Instituto Colombiano del Petróleo, cuyo objetivo es evaluar la calidad ecológica de los ríos de tierras bajas y de piedemonte dentro del área de influencia de Ecopetrol, a través de la implementación de un índice de calidad biológica utilizando diatomeas. Las 165 muestras analizadas hasta el momento provienen de muestras de perifiton de 83 sistemas lóticos de distintas regiones del país, de donde también se obtuvo información sobre temperatura del agua, pH, conductividad y oxígeno disuelto. El material fue estudiado con microscopio óptico y microscopio electrónico de barrido. Aquí reunimos 11 taxones de los cuales Achnanthidium macrocephalum(Hustedt) Round & Bukhtiyarova, Cymbopleura zimmermannii Metzeltin & Lange-Bertalot, Chamaepinnularia brasiliana Metzeltin & Lange-Bertalot, Ch. brasilianopsis Metzeltin & Lange-Bertalot, Planothidium lagerheimii (Cleve) Wetzel & Ector, Eunotioforma curvula (Hustedt) Kociolek & Burliga, Gomphonema archaevibrio fo. cuneatum Metzeltin & Lange-Bertalot, Gomphonema capitatum Ehrenberg, Nitzschia clausii Hantzsch y N. filiformis var. conferta (Richter) Lange-Bertalot se mencionan por primera vez para Colombia. Este es el primer registro del género Eunotioforma Kociolek & Burliga y por primera vez se describe e ilustra el género Chamaepinnularia Lange-Bertalot para el país. Además, analizamos la ultraestructura de Nitzschia dissipata(Kützing) Grunow, ya mencionada para el país pero solo analizada con MO. A pesar de ser esta especie considerada cosmopolita citada en las floras de diferentes regiones del mundo, ha sido frecuentemente mal identificada, por lo que este análisis nos permitió confirmar la identidad de los materiales colombianos.

This work was carried under the project for developing a biological water quality index for rivers of lowland waters of Colombia based on aquatic biological communities. A total of 165 sites were sampled considering the hidrogeomorphological variability among the studied rivers. In all sites, periphyton samples were collected by brushing rocks and then fixed with formalin 8%. The following information was also recorded: water temperature, pH, conductivity and dissolved oxygen. Biological samples were analyzed with light and scanning electron microscopy. Here we discussed the following 11 taxa recorded for the first time to Colombia: Achnanthidium macrocephalum(Hustedt) Round & Bukhtiyarova, Cymbopleura zimmermannii Metzeltin & Lange-Bertalot, Chamaepinnularia brasiliana Metzeltin & Lange-Bertalot, Ch. brasilianopsis Metzeltin & Lange-Bertalot, Planothidium lagerheimii (Cleve) Wetzel & Ector, Eunotioforma curvula (Hustedt) Kociolek & Burliga, Gomphonema archaevibrio fo. cuneatum Metzeltin & Lange-Bertalot, Gomphonema capitatum Ehrenberg, Nitzschia clausii Hantzsch and N. filiformis var. conferta (Richter) Lange-Bertalot. The genera Eunotioforma Kociolek & Burliga and Chamaepinnularia Lange-Bertalot are newly recorded for the country. We also analyzed the ultrastructure of Nitzschia dissipata (Kützing) Grunow already reported for the country but only studied with LM. Despite of being a species of cosmopolitan distribution, frequently cited in floras of different regions of the world, it is frequently misidentified so this analysis allowed us to confirm the identity of Colombian specimens.

Guadalupe Island represents a unique ecosystem. Its volcanic origin and remoteness from the Baja California peninsula have allowed for the successful establishment of its distinctive flora and fauna. However, the difficulty in accessing the island has precluded the study of its biotic communities, mainly the marine ones. Consequently, no studies on benthic or planktonic diatoms have been hitherto published. Thus, the first records of marine benthic diatom species (epiphytic, epilithic, epizoic) from Guadalupe Island in the NW Mexican Pacific are here provided. One hundred and nineteen diatom taxa belonging to the Bacillariophyceae and Fragilariophyceae were identified, including species and varieties. The former with 87 taxa was the most diverse. Thirteen taxa are new records for Mexico; photographic images of these are provided. Because this is the first study for the benthic diatoms of Isla Guadalupe, a particular bio-geographical affinity is not proposed. However, the best represented genus was Mastogloia which has tropical affinity, and Cocconeis thalassiana was also identified, a new species recently recorded for the Mexican Caribbean.

Isla Guadalupe es única como ecosistema; su origen volcánico y lejanía de la península de Baja California han permitido que el desarrollo evolutivo de sus distintivas flora y fauna haya sido exitoso. La dificultad para acceder a la isla es causa de que algunas comunidades, principalmente marinas, no hayan sido estudiadas aún. Consecuentemente, a la fecha no existía algún estudio publicado sobre diatomeas. Así, se presenta el primer registro de diatomeas bentónicas (epilíticas, epifitas y epizoicas) de isla Guadalupe en el noroeste de México. Se identificaron 119 taxa (incluyendo especies y variedades) de diatomeas pertenecientes a las clases Bacillariophyceae y Fragilariophyceae. Las primeras fueron más diversas con 87 taxa. Del total, 13 taxa son nuevos registros para México y se proveen imágenes fotográficas de ellos. Dado que se trata apenas del primer estudio para la flora de diatomeas bentónicas de isla Guadalupe, no se propone una afinidad biogeográfica. Sin embargo, uno de los géneros con mayor número de especies es de afinidad tropical, i.e., Mastogloia y se identificó Cocconeis thalassiana , una especie nueva recientemente registrada para el Caribe mexicano.

This study investigates the epilithic diatoms from the Dolores and Laja Rivers, located within the Upper Laja River Basin, Guanajuato, Mexico. The samples were collected during the cold-dry (January) and rainy (October) seasons of 2011. One-hundred seventy three infrageneric taxa were identified, 7 of which are new records for Mexico: Fallacia monoculata , Hantzschia abundans , Navigiolum uruguayense , Neidium bisulcatum , Nitzschia solita , Planothidium incuriatum and Sellaphora bacilloides; it is worth mentioning that Navigiolum is a new record at the genus level. Furthermore, 3 species are new records for the state of Guanajuato: Gomphonema laticollum , G.subclavatum and Gomphosphenia lingulatiformis. Teratological forms of 6 species were also found in the sampling sites with higher nutrient concentrations, with relative abundances varying from 0.8 to 8.3%.

Se presenta el registro de las diatomeas epilíticas de los ríos Dolores y Laja, localizados en la cuenca alta del río Laja, Guanajuato, México. Las muestras se recolectaron en las temporadas seca-fría (enero) y lluviosa (octubre) del 2011. Se identificaron 173 taxa infragenéricos, de los cuales 7 son nuevos registros para México: Fallacia monoculata , Hantzschia abundans , Navigiolum uruguayense , Neidium bisulcatum , Nitzschia solita , Planothidium incuriatum y Sellaphora bacilloides; cabe mencionar que Navigiolum es nuevo registro a nivel genérico. Además, 3 especies son nuevos registros para el estado de Guanajuato: Gomphonema laticollum , G.subclavatum y Gomphosphenia lingulatiformis. Se encontraron formas teratológicas en 6 especies con abundancias relativas que variaron de 0.8 a 8.3%, siendo estas formas más abundantes en los sitios con mayores concentraciones de nutrientes.