Staurosira magallanesica, a replacement name for Staurosira patagonica

Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales described a new species found in material of Maar Magallanes, Patagonia, Argentina and other lakes in southern Patagonia. This new species was analysed in detail by light and electron microscopy and a comprehensive description is given in Garcia et al. (2017: 107, 114, figs 2-45). However, this name is a later homonym of Staurosira patagonica Cleve, 1882. If we compare our species to Cleve’s illustration (Cleve 1882: pl. 16: fig. 13), we can easily differentiate the two by their general valve outline and morphometric data. As pointed out by Garcia et al. (2017), re-examination of the type material of members of the Fragilariaceae is needed to confirm identities, establish taxonomic boundaries and to facilitate identification, and this is also the case with Staurosira patagonica Cleve. A new name is, however, required for Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales as it is an illegitimate name: Staurosira magallanesica M.L.Garcia, Maidana, Ector & E.Morales nom. nov. Replaced synonym: Staurosira patagonica M.L.Garcia, Maidana, Ector & E.Morales Nova Hedwigia, Beiheft 146: 107, 114, figs 2-45, 2017, nom illeg., non Staurosira patagonica Cleve 1882 Öfversigt af Kongliga Svenska Vetenskaps-Akademiens Förhandlingar 38(10): 13, pl. 16: fig. 13, 1882 ‘1881’. Etymology: we have derived the specific epithet from the name of the paleolake Maar Magallanes where this new species was found for the first time by N.I. Maidana (Maidana & Corbella 1997).Fil: García, María Luján. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Maidana, Nora Irene. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Biodiversidad y Biología Experimental; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Biodiversidad y Biología Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y Biología Experimental y Aplicada; ArgentinaFil: Ector, Luc. Luxembourg Institute of Science and Technology; LuxemburgoFil: Morales, E. A.. Universidade de Évora; Portuga

Diatom assemblages in Portuguese temporary rivers

During a survey of benthic diatoms in watercourses from Portugal in spring and summer 2006 and 2007, 76 sites in temporary streams (according to the National Water Institute classification) have been studied. These streams belong to the Ribeiras do Algarve (10 sites), Guadiana (19 sites), Mira (7 sites), Sado (16 sites), Tejo (20 sites), and Douro (4 sites) watersheds. Among these 76 sites, the National Water Institute classified only 48 as reference sites, and only these were therefore considered in the statistical analysis performed. A total of 276 diatom taxa have been identified in the 48 reference sites, from which 112 were present in abundance above 2% in at least one inventory. The most frequent taxa, present in more than 50% of the studied sites, were Achnanthidium minutissimum (Kützing) Czarnecki, Amphora pediculus (Kützing) Grunow, Cocconeis euglypta Ehrenberg, Eolimna minima (Grunow) Lange-Bertalot, Gomphonema parvulum Kützing, G. rosenstockianum Lange-Bertalot & E. Reichardt, Navicula gregaria Donkin, N. veneta Kützing, Nitzschia inconspicua Grunow and Planothidium frequentissimum (Lange-Bertalot) Lange-Bertalot. These are neutrophilous to alcaliphilous, mesosaprobous to -meso-saprobous, eutraphentic to indifferent taxa. Furthermore, a multivariate analysis relating diatom assemblages with environmental parameters is presented and the ecological preferences of not yet well known taxa, such as G. rosenstockianum, are provided

Hydrological connectivity inferred from diatom transport through the riparian-stream system

Funding for this research was provided by the Luxembourg National Research Fund (FNR) in the framework of the BIGSTREAM (C09/SR/14), ECSTREAM (C12/SR/40/8854) and CAOS (INTER/DFG/11/01) projects. We are most grateful to the Administration des Services Techniques de l’Agriculture (ASTA) for providing meteorological data. We also acknowledge Delphine Collard for technical assistance in diatom sample treatment and preparation, François Barnich for the water chemistry analyses, and Jean-François Iffly, Christophe Hissler, Jérôme Juilleret, Laurent Gourdol and Julian Klaus for their constructive comments on the project and technical assistance in the field.Peer reviewedPublisher PD

MORPHOLOGICAL DIVERSITY WITHIN THE ACHNANTHIDIUM MINUTISSIMUM SPECIES COMPLEX

During a survey of benthic diatoms sampled in watercourses from Mainland Portugal, several Achnanthidium populations morphologically ascribable to the A. minutissimum complex have been found. They clearly belong to the genus Achnanthidium on the basis of the valve outline, radiate striae, uniseriate, wider spaced striae in the centre of the valve and cells shallow‐V‐shaped in girdle view. The raphe valve has a straight central raphe hardly expanding at the centre and a row of elongated areolae in the mantle. Within the genus Achnanthidium these morphotypes belong to the complex of A. minutissimum (Kützing) Czarnecki, due to their straight terminal raphe fissures, in opposition to the species with terminal raphe fissures clearly deflected on the same side of the valve. Since these individuals were abundant in numerous sites, especially in the Centre and North of Portugal, a more detailed examination was performed by means of light (LM) and scanning electron microscopy (SEM). Furthermore, the examination of the environmental characteristics of the sites where they have been sampled allowed us to gather sufficient information on the ecological preferences of the different taxa. The main features that allow the separation of these taxa among each other and from all the other known Achnanthidium species are the different valve outline and dimensions, the size and shape of the central area, the apices shape and the density of the striae throughout the valve and near the apices. The LM and SEM analyses of the type materials of Achnanthidium microcephalum Kützing, Achnanthes minutissima Kützing and A. minutissima var. cryptocephala Grunow in Van Heurck have been done in order to help to clarify the taxonomy of this group. A comparison with the literature on Achnanthidium minutissimum species complex was performed, but the new Portuguese Achnanthidium taxa present a set of distinct morphological and ecological features that separate them well from all other similar species. Furthermore, two of these taxa have already been recorded from French watercourses with similar environmental characteristics

A new common species Achnanthidium caravelense (Bacillariophyceae) discovered in the rivers of North of Portugal

Achnanthidium caravelense Novais et Ector is described as a new species based on light and scanning electron microscopic observations, as well as on its ecological preferences as reconstructed from field observations (Novais et al. 2011). The most characteristic morphological features of this species are the different outline of the raphe valve (narrowly elliptic with linear margins) and the rapheless valve (narrowly elliptic to narrowly rhombic with moderately convex margins), the non-protracted broadly rounded apices and the length/width ratio. Furthermore, the areolae of the single row along the mantle are elongated and are more or less widely open, which is a characteristic discernible in girdle view under light microscopy. A comparison with the morphologically similar species Achnanthes standeri Cholnoky, A. taiaensis J. R. Carter, Achnanthidium affine (Grunow) Czarn., A. eutrophilum (Lange-Bert.) Lange-Bert., A. exile (Kütz.) Round et Bukht. and A. minutissimum (Kütz.) Czarn. revealed that the species that A. caravelense resembles most is A. eutrophilum. Nevertheless it can be distinguished from the latter by the different raphe valve outline, its higher valve length/width ratio and ecological preferences. Achnanthidium caravelense is characterized by a set of distinct morphological and ecological features that separate it well from all other similar Achnanthidium species and it is common and abundant in soft water rivers with low to moderate nutrient content in the North of Portugal. There is therefore a rather high probability that this species also occurs in other European countries in rivers with suitable conditions but this Achnanthidium has not yet been recorded due to probable misidentifications with A. eutrophilum or A. minutissimum

Diatoms of temporary and permanent watercourses in Southern Europe (Portugal)

The potential importance of benthic diatoms in Mediterranean watercourses has received limited academic attention historically. This study sought to provide baseline information for this poorly studied group. Temporary and permanent watercourses in Portugal differ in catchment characteristics, climatic variables and water chemistry. The benthic diatom communities were characterized in terms of ecological preferences and conservation status for taxa with relative abundance above 1% in at least one site covering 39 temporary sites (109 taxa) and 53 permanent sites (130 taxa). The low-profile guild dominated both temporary and permanent watercourses, followed by the high-profile and motile guilds. Indicator value analysis indicated that Amphora copulata, Cocconeis placentula, Diploneis separanda, Encyonopsis subminuta, Fragilaria radians, Gomphonema olivaceum, Gomphonema truncatum, Halamphora veneta, Navicula radiosa, Navicula veneta, Sellaphora seminulum and Ulnaria acus were indicators of temporary watercourses, whereas Encyonema minutum, Eunotia minor, Fragilaria rumpens, Fragilaria cf. socia and Navicula rhynchocephala were characteristic of permanent watercourses. Ecological preferences of indicator taxa were inferred on the basis of environmental variables that differed significantly between temporary and permanent watercourses. The importance of temporary watercourses for the maintenance of diatom biodiversity is discussed and explored

Morphology and ecology of Achnanthidium caravelense (Bacillariophyceae), a new species from Portuguese rivers

A new benthic freshwater diatom species belonging to the genus Achnanthidium Kütz. has been recorded from several watercourses in the North of Portugal. Achnanthidium caravelense Novais et Ector is described as a new species based on light and scanning electron microscopic observations, as well as on its ecological preferences as reconstructed from field observations. The most characteristic morphological features of this species are the different outline of the raphe valve (narrowly elliptic with linear margins) and the rapheless valve (narrowly elliptic to narrowly rhombic with moderately convex margins), the non-protracted broadly rounded apices and the length/width ratio. Furthermore, the areolae of the single row along the mantle are elongated and are more or less widely open, which is a characteristic discernible in girdle view under light microscopy. The species that A.caravelense resembles most is A. eutrophilum (Lange-Bert.) Lange-Bert.; nevertheless it can be distinguished from the latter by the different raphe valve outline, its higher valve length/width ratio and autecology. A. caravelense is common and abundant in soft waters with low to moderate nutrient content in the North of Portugal

Response of epilithic diatom communities to environmental gradients in subtropical temperate Brazilian rivers

This work aims to analyse the response of epilithic diatom communities to enviranmental gradients in subtropical temperate southern Brazilian rivers to contribute to the development of a widely applicable methodology for water-quality monitoring. Samples for physical, chemical and biological determination were collected monthly, fram December 2001 to November 2002 and fram March 2003 to February 2004, at 9 stations along the rivers Pardo and Pardinho in the hydrographical basin of Rio Pardo, State of Rio Grande do Sul (RS), Brazil. Physical and chemical variables (water temperature, pH, dissolved oxygen, biochemical oxygen demand, chemical oxygen demand, nitrates, nitrites, phosphates and total dissolved solids) and biological variables (epilithic diatom communities) were used as parameters for water-quality assessment. The data matrix was examined by means of a multivariate ordination using Detrended Correspondence Analysis (DCA). In total, 270 taxa were identified to specific or infra-specific levels. The results showed that of all the physical and chemical variables used, the main gradient along the DCA first axis was eutraphication, which was indicated by its significant correlation with phosphates (p < 0.00l). Hence, the species' scores on the DCA axis were used as an operational criterion for indicating their tolerance to eutrophication. From this analysis, the 10 taxa that were the most tolerant to eutrophication were: Cyclotella meneghiniana, Fallacia monoculata, Nitzschia acicularis, N. clausii, N. nana, N. palea, Nitzschia sp., Pinnularia sp., Sellaphora pupula sensu lato and Ulnaria acuso The present study showed that epilithic diatom assemblages reflect anthropogenic changes in hydrographic basins in subtropical temperate streams, especially pollution by organic enrichment and eutraphication. Key words: Diatoms, eutrophication, biomonitoring, southern Brazilian rivers.Este trabajo pretende analizar la respuesta de la comunidad de diatomeas epilíticas a gradientes ambientales en ríos brasileños templados subtropicales, con el objetivo de contribuir al desarrollo de una metodología ampliamente aplicable para la monitorización de la calidad del agua. Diversas muestras para determinaciones físicas, químicas y biológicas fueron recogidas mensualmente, de diciembre de 2001 a noviembre de 2002, y de marzo de 2003 afebrero de 2004, en nueve esta­ciones de muestre o distribuidas a lo largo de los ríos Pardo y Pardinho, localizados en la Cuenca Hidrográfica del Río Pardo, Estado del Río Grande del Sur; Brasil. Variables físicas y químicas (temperatura del agua, pH, oxígeno disuelto, demanda bioquímica de oxígeno, demanda química de oxígeno, nitratos, nitritos, fosfato y sólidos totales disueltos) y biológicas (co­munidad de diatomeas epilíticas) fueron usadas como parámetros para evaluar la calidad del agua. El conjunto de datos fue analizado por medio de una ordenación multivariante usando el Análisis de Correspondencias sin Tendencias (DCA). En total, 270 taxones fueron identificados a nivel especifico o infra-especifico. Los resultados indicaron que, entre todas las variables físicas y químicas usadas, el principal gradiente establecido a lo largo del primer eje DCA fue la eutrojización, señalada por su correlación significativa con la concentración de fosfatos (p < 0.001). De esta forma, los valores alcanzados por las especies en el primer eje DCA fueron usados como un criterio operativo para indicar su tolerancia a la eutrojización. Los 10 taxones más tolerantes a la eutrojizaciónfueron: Cyc10tella meneghiniana, Fallacia monoculata, Nitzschia acicularis, N. c1ausii, N. nana, N. palea, Nitzschia sp., Pinnularia sp., Sellaphora pupula sensu lato y Ulnaria acuso El presente estudio muestra que la comunidad de diatomeas epilíticas refleja cambios antropogénicos en ríos templados subtropicales de cuencas hidrográjicas, especialmente la contaminación por enriquecimiento orgánico y eutrofización

Estudio comparativo del estado ecológico de los ríos de la cuenca del Ebro mediante macroinvertebrados y diatomeas

Se ha estudiado durante el verano de 2002 el estado ecológico en 87 estaciones de muestreo repartidas a lo largo de la cuenca del Ebro (España) mediante diferentes índices bóticos de macroinvertebrados y diatomeas. La mayor parte de las estaciones analizadas alcanzaron al menos un nivel de estado ecológico "Bueno", pero se vieron algunas diferencias entre los distintos tipos fluviales existentes, teniendo una mejor calidad aquellos tipos correspondientes a zonas de cabecera y ríos de montaña. En general las estaciones con un estado ecológico peor correspondían a tramos bajos de ríos cercanos a núcleos urbanos e industriales, zonas con importante actividad agrícola y ganadera o tramos por debajo de embalses. Se ha observado una correlación positiva significativa entre los índices de macroinvertebrados y diatomeas empleados, tanto en lo concerniente a los valores obtenidos, como respecto a las clases de estado ecológicas resultantes.During the summer of 2002 the water ecological status of 87 sample stations of different rivers along the Ebro River basin (Spain) was studied using different biotic indices based on benthic macroinvertebrates and diatoms. Most of the sample points studied in 2002 reached at least a "Good" ecological status but some differences between the different existing fluvial types were observed. Upper river stretches and mountain rivers had higher ecological status. In general the sampling stations with the worst ecological status level were mainly located downstream, close to urban and industrial areas, near agricultural or livestock areas or downstream dams. A positive, significant correlation was observed between macroinvertebrate and diatom indices, both concerning the values obtained and the resulting ecological status categories