Two new species of Staurosira and Pseudostaurosira (Bacillariophyta) from the highlands of Argentina (south-central Andes) and two new nomenclatural combinations

Grana, Lorena; Morales, Eduardo A.; Maidana, Nora I.; Éctor, Luc

doi:10.11646/phytotaxa.365.1.2

Cited by 6 publications

(9 citation statements)

References 23 publications

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“…Las especies pertenecientes a los géneros Staurosira y Pseudostaurosira poseen mayor número de registros en la bibliografía, si bien han sufrido múltiples revisiones desde su descripción original (Cejudo-Figueiras et al, 2011;Grana et al, 2018). Staurosira es un género antiguo redefinido luego de la revisión del género Fragilaria.…”

Section: Discusión Fragilarioides Fósiles Del Río Coloradounclassified

“…La disposición marginal de las estrías genera un área axial amplia en la valva (Figura 3H). Posee campos de poros reducidos y por lo general las espinas interrumpen las estrías (Grana et al, 2018). Pseudostaurosira ha sido definido tradicionalmente como un género con representantes salobres-dulceacuícolas oligotróficos a mesotróficos [e.g.…”

Section: Discusión Fragilarioides Fósiles Del Río Coloradounclassified

“…Ambos géneros Staurosira y Pseudostaurosira han sido reconocidos ampliamente en sedimentos holocenos de Argentina, conformando ensambles salobre-dulceacuícolas en sistemas estuáricos y lacustres (Espinosa, 1994(Espinosa, , 2008Hassan et al, 2009Hassan et al, , 2011Espinosa et al, 2012;Prieto et al, 2014;Fayó et al, 2018;Guerrero et al, 2019, entre otros). Pseudostaurosira oliveraiana Grana, E. Morales, Maidana & Ector fue descripta recientemente en sedimentos holocenos de lagos salinos del noroeste de Argentina (Grana et al, 2018); el mismo año esta especie fue registrada como Psudostaurosira sp. en los sedimentos holocenos del río Colorado (Fayó et al, 2018).…”

Section: Discusión Fragilarioides Fósiles Del Río Coloradounclassified

“…Sin embargo, sólo los trabajos más recientes abordan la identificación taxonómica de las diatomeas fósiles con los nuevos criterios de clasificación y el uso combinado de LM y MEB (e.g. García & Maidana, 2015;García et al, 2017;Fayó et al, 2018, Grana et al, 2018.…”

Section: Introductionunclassified

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Diatomeas holocenas del delta del río Colorado, Argentina. Una aproximación paleoambiental a partir del estudio de “fragilarioides pequeñas”

Fayó

Espinosa

Isla

2020

Rev. bras. paleontol.

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Holocene diatoms of the Colorado River Delta, Argentina. A paleoenvironmental approach from the study of "small fragilarioids". Diatom assemblages of a sedimentary succession in the deltaic plain of the Colorado River (Argentina) were studied in order to reconstruct the paleoenvironmental conditions of the delta in response to Holocene sea-level changes. A 191 cm depth core was extracted by vibracoring from Las Isletas (LI), located 22 km from the coast (39°43'5.7"S, 62°20'49.7"W). A cluster analysis -CONISS of 35 subsamples defined three diatom zones (DZ). The sedimentary succession is dominated by small fragilarioids, being Punctastriata glubokoensis Williams, Chudaev & Gololobova the most abundant species; the accompanying flora included fresh-brackish and allochthonous marine-coastal taxa. At the base, subzone DZIA (191-163 cm, 7,315±64 14 C yr BP) included sandy lithological units and presented abundant marine-coastal species. The overlying subzone DZIB (163-96 cm) has low abundance of allochthonous marine species. The uppermost zone, DZII (96 cm from the top) integrate the silt-sandy lithological units, and it was deposited ca. 2,218±29 14 C yr BP. DZII lacked marine species. The LI sequence represents the infilling of a river-estuarine channel with tidal influence ca. 7,300 14 C yr BP that gradually evolved into a fresh-brackish river channel, similar to the current river, ca. 2,200 14 C yr BP. During the Middle Holocene transgression, the greatest marine influence would have transported coastal marine species upstream to the LI site; the increase of fluvial influence associated with the progradation of the delta lobe would have favored the ubiquity and persistence of the small fragilarioids in the fluvial-delta assemblages of the Colorado River during the last ca. 7,000 14 C yr BP.

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Section: Discusión Fragilarioides Fósiles Del Río Coloradounclassified

Section: Introductionunclassified

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Diatomeas holocenas del delta del río Colorado, Argentina. Una aproximación paleoambiental a partir del estudio de “fragilarioides pequeñas”

Fayó

Espinosa

Isla

2020

Rev. bras. paleontol.

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“…Reliably species indicators include P. glubokoensis, P. oliveraiana and D. tenuis which in turn displayed the highest conductivity optima. Grana et al (2018) identified to P. oliveraiana in Holocene sediments from the saline Laguna Colorada (Argentinian Altiplano). Although other small araphid diatoms as S. venter, P. brevistriata and P. lancettula also show high inferred optima, they are poor indicators of conductivity because they present wide tolerances.…”

Section: Species Optimamentioning

confidence: 99%

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

2021

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Dryland river systems support a diverse aquatic biota in semi-arid and arid landscapes, but they are increasingly vulnerable to natural and human impacts. This study provides the first modern diatom training set (n = 38) from three dryland rivers in northern Patagonia, Argentina. The relationship between surface-sediment diatoms and contemporary environmental variables was explored using multivariate analyses. The results showed that surface-water chemistry varies among rivers in accordance with local-scale factors such hydro-climatic variability and anthropic activities. A total of 378 diatom taxa were identified but only 45 taxa occurred with relative abundances higher than 2% in at least one sediment sample. The Colorado and Negro rivers were characterized by high abundances of small tychoplanktic fragilarioids whereas the Chubut River was dominated by epiphytic and planktic taxa. The canonical correspondence analyses (CCA) showed that conductivity, pH and HCO 3 − were the main environmental variables governing diatoms distributions. A transfer function was developed for water conductivity using unimodal methods because of partial CCA and λ 1 /λ 2 ratio revealed that this variable had the largest unique effect on diatom variance. A weighted averaging (WA) model with tolerance downweighting and classic deshrinking provided a reasonably robust model (r 2 jack = 0.94 and RMSEP = 0.249 log 10 μS cm −1 ). However, the diatom-inferred conductivity values should be carefully interpreted because of the uneven distribution of sampling sites and the dominance of small araphid diatoms belonging to the genera Staurosira, Pseudostaurosira and Punctastriata. By their benthic habitat, the distribution of these taxa could be influenced by other factors as light and substrate in addition to water chemistry. The autoecological information achieved through this study will provide the basis for a better insight into the hydrological responses of the dryland rivers in northern Patagonia to climate and environmental changes.

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New araphid species of the genusPseudostaurosira(Bacillariophyceae) from southern Patagonia

García

Bustos

Villacís

et al. 2021

European Journal of Phycology

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Two new species of Staurosira and Pseudostaurosira (Bacillariophyta) from the highlands of Argentina (south-central Andes) and two new nomenclatural combinations

Cited by 6 publications

References 23 publications

Diatomeas holocenas del delta del río Colorado, Argentina. Una aproximación paleoambiental a partir del estudio de “fragilarioides pequeñas”

Diatomeas holocenas del delta del río Colorado, Argentina. Una aproximación paleoambiental a partir del estudio de “fragilarioides pequeñas”

Diatom-based inference model for conductivity reconstructions in dryland river systems from north Patagonia, Argentina

New araphid species of the genusPseudostaurosira(Bacillariophyceae) from southern Patagonia

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