The water-soluble chitosan derivative, N-methylene phosphonic chitosan, is an effective fungicide against the phytopathogen Fusarium eumartii

Chitosan has been considered an environmental-friendly polymer. However, its use in agriculture has not been extended yet due to its relatively low solubility in water. In an attempt to improve such chemical characteristics, a chitosan-derivative prepared by adding a phosphonic group to chitosan N-methylene phosphonic chitosan, NMPC, was obtained from shrimp fishing industry waste from Argentinean Patagonia. This study showed that NMPC had a fungicidal effect on the phytopathogenic fungus Fusarium solani f. sp. eumartii (F. eumartii). NMPC inhibited F. eumartti mycelial growth and spore germination with low IC50 values. In vivo studies showed that NMPC affected fungal membrane permeability, ROS production, and cell death. NMPC also exerted antifungal effects against two other phytopathogens, Botrytis cinerea, and Phytophthora infestans. NMPC did not affect tomato cell viability at the same doses applied to these phytopathogens. Furthermore, the selective cytotoxicity of NMPC could give it added value in its application as an antimicrobial agent in agriculture.

Fossil woods from the Eocene of Corcovado, Argentinean Patagonia: geological setting and conifer diversity

Eocene paleofloras of Patagonia are diverse and increasingly known. A new assemblage of fossil wood has been recovered from Eocene sediments in Corcovado, western Argentinean Patagonia. The lithological succession (formerly Arroyo Lyn Formation sensu Pesce 1979) is correlated with the Huitrera Formation. The specimens were mostly found embedded in sandstones and conglomerates. One-third of the assemblage are conifers and studied herein. We found four taxonomic types: Agathoxylon cf. antarcticum (Araucariaceae), Phyllocladoxylon antarcticum (Podocarpaceae), Podocarpoxylon dusenii (Podocarpaceae), and Cupressinoxylon hallei (Cupressaceae or Podocarpaceae). The presence of four taxonomic units among only 7 specimens suggests a significant conifer species richness in the assemblage. Araucariaceae and dominant Podocarpaceae are usually found in previously described conifer wood assemblages from the Eocene of Patagonia andAntarctica. The diversity of the conifer assemblage in Corcovado is very similar to that found at Laguna del Hunco (these two localities are 170 km distant), also from the Huitrera Formation. This is consistent with the proposal that the bearing sediments of both localities are from the same stratigraphic unit.

Two new freshwater planarian species (Platyhelminthes: Tricladida: Dugesiidae) partially sympatric in Argentinean Patagonia

Girardia Ball, 1974 is the most diverse and widely distributed genus of the family Dugesiidae (Platyhelminthes: Continenticola) in the Neotropical region. Seven out of the 52 species of the genus are known for Argentina. The Somuncurá Plateau is a region in northern Patagonia with several endemic flora and fauna, but little is known about the free-living Platyhelminthes. We describe two new species of Girardia partially inhabiting in sympatry in the Somuncurá Plateau: Girardia somuncura sp. nov. and Girardia tomasi sp. nov. The identification criteria that we followed was an integrative taxonomic approach based on morphological and molecular data. Thus, we used anatomical features focused on the reproductive system, together with a phylogenetic analysis, using a mitochondrial (COI barcode region) genetic marker. This study is the first phylogenetic analysis of the genus Girardia in which we include the southernmost representatives of America here described, thus making it possible to incorporate them in global phylogenies.

Un evento de floración en el género Chusquea (Poaceae, Bambusoideae, Bambuseae)

Flowering in woody bamboos is an intriguing phenomenon. Documenting a flowering event provides valuable information about bamboo life cycles. Chusquea argentina is a species endemic to the Andean Patagonian beech forests of Argentina and Chile. We here report a flowering event of C. argentina in northwestern Argentinean Patagonia. We provide a map of the area indicating flowering sites. Photographs showing details of the flowering event are presented. The epidemiological effects of the flowering of C. argentina are taken into consideration.