Three new species of Luticola are described from lotic ecosystems in Andakí Municipal Natural Park, located in the Andean-Amazon region on the eastern flank of the eastern Andes mountain range in Colombia. Size and morphological features of the three new species, L. caquetensis Kociolek, Simonato & Núñez-Avellaneda sp. nov., L. andakiesiorum Simonato, Kociolek & Plata Díaz sp. nov., and L. sinchii Sala, Kociolek & Simonato sp. nov. are provided, based on light and scanning electron microscopical observations, and compared with similar congeners. Species of the genus are organized into groups depending upon whether they possess or lack marginal channels and/or pseudosepta. All the new species possess pseudosepta and L. caquetensis and L. andakiesiorum lack marginal channels. The two latter species share this combination of features with Luticola affinis Levkov et al., a species described from Brazil. These species thus form a unique group within the genus, offering additional evidence for the unique biodiversity found in this region.

Halamphora siqueirosii sp. nov. is a marine benthic diatom isolated as a monoclonal culture from a hypersaline evaporation pond at the Guerrero Negro Saltworks, Baja California Sur, Mexico. Analysis of the valve ultrastructure of this taxon using light and electron microscopy indicated that its uniseriate striae and the density of its dorsal striae are useful characteristics for discriminating H. siqueirosii from other species with similar morphological patterns. The phylogenetic analyses performed with nuclear ribosomal genes, the small (18S) and large subunits (28S), and chloroplast gene ribulose-bisphosphate carboxylase (rbcL) fragments showed that H. siqueirosii is closely related to H. americana, H. calidilacuna and H. incelebrata. Morphological differences between this new species and similar ones are discussed.

During a survey of the diatoms present in aerophilic microhabitats associated with waterfalls in Misiones Province (Argentina), mainly within Iguaz? National Park (N.P.), seventeen taxa belonging to the genus Humidophila have been recorded. Pr...

Introducción y objetivos: Didymosphenia geminata, diatomea declarada “Especie Exótica Invasora” en Argentina por la Secr. Ambiente y Desarrollo Sustentable de la Nación. Esta especie coloniza rocas y puede formar grandes matas mucilaginosas que cubren el lecho de los ríos, ocasionando un considerable impacto estético y provocando serias alteraciones en los ecosistemas. En los últimos 9 años la especie ha colonizado ríos andino-patagónicos y ha aumentado considerablemente su distribución en la región. El objetivo de este trabajo es analizar la dinámica de esta especie en la Patagonia argentina mediante el uso de SIG.M&M: los datos provienen de resultados obtenidos por el grupo de trabajo en las provincias del Neuquén y del Chubut e información abierta y libre disponible en la web. Se generó una base de datos a escala regional abarcando desde Neuquén a Tierra del Fuego.Resultados: fueron incorporados a un SIG, lo que permitió generar mapas de distribución a nivel provincial y nacional. Conclusiones: los datos disponibles hasta marzo de 2018 muestran que D. geminata, ha expandido su distribución entre 2010 y 2018 desde la provincia del Chubut hacia el norte alcanzando la provincia de Neuquén y hacia el sur llegando a Tierra del Fuego.

During a survey of diatoms from the Colombian and Peruvian Amazon, we encountered many specimens of the genus Stenopterobia in periphyton and plankton samples. These diatoms were assigned to three different taxa, two with sigmoid valves and the other one with straight valves. The comparison of their valve morphologies with similar taxa described in the literature revealed that they do not correspond to any previously known taxa. They are described herein as Stenopoterobia caquetaensis sp. nov., S. colombiana sp. nov. and S. amazonica sp. nov. We maintain this genus assignment since the new taxa, as well as other species currently in Stenopterobia, exhibit differences from Iconella, a genus to which several Stenopterobia species were recently transferred. Differences exist between the two genera in their ultrastructural features, such as plain internal valve face and unrimmed internal areolar openings, which do not fully conform to the description of Iconella. Additionally, the robustoid Surirella rafaelii and S. tayronarum, recently described from Colombia, are transferred to Iconella.