Abstract Perithemis mooma, Kirby, 1889 and Perithemis icteroptera (Selys in Sagra, 1857) live in sympatry from southern Brazil to central Argentina. The taxonomy of the genus Perithemis Hagen, 1861 has been hampered by the use of characters that are highly variable or show slight differences among species. Our objective was to assess the efficiency of traditional morphometrics (TM) and geometric morphometrics (GM) to discriminate between these species using wing size and shape and vulvar lamina contour, and to analyze the presence of sexual dimorphism in wing size and shape in both species. The TM and landmark-GM methods were applied on the fore and hind wings, while the outline-based GM method was applied on the vulvar lamina. GM allowed species delimitation using shape variables of either wing. The wing and vulvar lamina shapes were confirmed to be good diagnostic characters to separate these species and appear to be promising tools for distinguishing among other species of this genus. Centroid size failed to achieve species separation. Both species exhibited sexual size dimorphism (SSD). In contrast to what would be expected for Perithemis whose males are strongly territorial, P. icteroptera and P. mooma showed female-biased SSD suggesting a common pattern in Perithemis.

Abstract A new coenagrionid genus, Negragrion, is described for N. sagma sp.n. found in Argentina and Brazil (Holotype and allotype, pair in tandem. Argentina: Corrientes: Santo Tomé, arroyo Ita Cuá sobre RP 94, 28°26’48.30”S 56°00’33.11”W, 24.ii.2003, Muzón & Pessacq coll., MLP). The new genus is characterized by the shape of male cerci (decumbent from base; saddle-shaped; in lateral view with an acute apophysis directed dorsally located at 0.3 from base). The presence of a vulvar spine on S8 of females places this genus within Ischnurinae. A cladistics analysis using morphological data was carried out to determine its phylogenetic position. Negragrion gen.n. is recovered within the clade 4 as the sister group of the clade (Acanthallagma Acanthagrion (Oxyagrion, Fluminagrion)).

Abstract The American genus Argia, with more than 100 species described, is the most speciose genus of Odonata in the world. In this contribution, the final stadium larva of Argia serva, the southernmost distributed species of Argia, is described and diagnosed based on reared material from Martín García island, Buenos Aires, Argentina. The larva of this species can be easily separated from the other Argentinean Argia by the following combination of characters: sternum of S8 covered with spines (bare in A. translata); antennal segment 3 longer than 1+2 (equal to or shorter than 1+2 in A. joergenseni and A. jujuya); palpal setae absent (present in A. croceipennis). A key to the known larvae of Argia of the Southern Cone is provided.

On the basis of recently collected specimens belonging to Odonata (Coenagrionidae, Aeshnidae, Gomphidae, and Libellulidae), Hemiptera (Corixidae and Notonectidae) and Diptera (Ceratopogonidae and Culicidae), new records and new localities of aquatic insects for the Somuncurá plateau and its area of influence (Argentinean Patagonia) are provided. Forty seven species in 20 genera are recorded, 25 of which for the first time from the area. Of them, 17 represent new records from Somuncurá, four from extra-andean Patagonia, one from Patagonia and three species are new to science. Two genera are recorded for the first time from Somuncurá, one of which is new from extra-andean Patagonia. The identity of five species previously recorded is established. Taking into account the preliminary inventory and recent bibliography, the total number of aquatic insects registered from the Somuncurá plateau increases to 104 species, grouped in 53 genera.

Se brindan nuevas citas y localidades de los insectos acuáticos de la Meseta de Somuncurá y su área de influencia (Patagonia, Argentina), sobre la base de recolecciones de los órdenes Odonata (familias Coenagrionidae, Aeshnidae, Gomphidae y Libellulidae), Hemiptera (familias Corixidae y Notonectidae) y Diptera (familias Ceratopogonidae y Culicidae). Se registran 47 especies (agrupadas en 20 géneros), de las cuales 25 se citan por primera vez para el área. De ellas, 20 representan nuevos registros para Somuncurá (incluso tres especies nuevas para la ciencia), cuatro nuevas para la Patagonia extra-andina y una para la Patagonia. Se mencionan por primera vez dos géneros para Somuncurá, uno de los cuales es nuevo para la Patagonia extra-andina. Asimismo, se esclarece la identidad de cinco especies citadas previamente. Teniendo en cuenta el inventario preliminar y bibliografía reciente, el número total de especies de insectos acuáticos registrados en la Meseta de Somuncurá asciende a 104, agrupadas en 53 géneros.

The Odonata order is represented in Patagonia by 36 species belonging to nine families and 18 genera. The endemicity level is high being approximately 60% of the species and 40% of genera endemic. The specific richness in Patagonia decreases from West to East and from North to South, being Nahuel Buta (Chile) and Andes mountains between 38° and 41° S on the forest area, and the Somuncurá plateau (Argentina) on the steppe the richest areas. An update of its records and an analysis of the main distribution patterns are provided in this paper.

El orden Odonata se encuentra representado en la Patagonia por 36 especies, reunidas en nueve familias y 18 géneros. El nivel de endemismo de esta taxocoenosis es alto, aproximadamente el 60% de las especies y casi el 40% de los géneros endémicos. La riqueza específica en la Patagonia decrece de Oeste a Este y de Norte a Sur, las áreas de mayor riqueza resultan ser las cordilleras de Nahuel Buta (Chile) y de los Andes entre 38° y 41° S, y la meseta de Somuncurá (Argentina) en la estepa. Se brinda una actualización del estado de conocimiento y un análisis de los principales patrones de distribución.

A preliminary inventory of the Odonata from Iberá Wetlands and their area of influence (Corrientes, Argentina) is presented. Different kinds of environments were surveyed in seven localities. Seventy five species grouped in 33 genera and seven families were registered, from which three genera and 10 species are new records for the country. The localities belonging to the Iberá Wetland system show low endemicity and a high faunistic relationship with the Paraná basin.

Se presenta un inventario preliminar de los Odonata de los Esteros del Iberá, así como su área de influencia (Corrientes, Argentina). Distintos tipos de ambientes fueron muestreados en siete localidades. Se registraron setenta y cinco especies agrupadas en 33 géneros y siete familias, de las cuales tres géneros y 10 especies son nuevos registros para el país. Las localidades que pertenecen al sistema de Esteros del Iberá, muestran bajos niveles de endemismo y una similitud faunística elevada con la cuenca del Paraná.

ABSTRACT. A preliminary inventory of the aquatic insects from the Somuncura plateau and its area of influence (Patagonia, Argentina) is presented. It was done on the basis of the study of collections and previous records of species belonging to the orders Ephemeroptera, Odonata, Hemiptera (Heteroptera), Trichoptera, Diptera (families Ceratopogonidae, Culicidae, and Psychodidae) and Coleoptera. Different kinds of environments were surveyed in 14 localities. Seventy eigth species grouped in 51 genera and 26 families were registered, and 33 species are new records for the area. Eighty three % of the registered genera are widely distributed (neotropical, american or cosmopolitan), while 41 % of the species exhibit patagonic or andean distribution.

RESUMEN. Se brinda un inventario preliminar de los insectos acuáticos de la Meseta del Somuncura y su área de influencia (Patagonia, Argentina) realizado sobre la base de colecciones y registros previos de especies pertenecientes a los órdenes Ephemeroptera, Odonata, Hemiptera (Heteroptera), Trichoptera, Diptera (familias Ceratopogonidae, Culicidae y Psychodidae) y Coleoptera. Se han relevado diversos tipos de ambientes en 14 localidades. El número de especies registrado asciende a 78, agrupadas en 51 géneros y 26 familias, de las cuales 33 se citan por primera vez del área. De los taxa registrados 83% de los géneros corresponden a grupos de amplia distribución (neotropicales, americanos o cosmopolitas), mientras que 41% de las especies presentan una distribución patagónica o andina.

ABSTRACT. The history of classifications of insects is revised from its relationships within Arthropoda (e.g., Unirramia, Mandibulata, Atelocerata, Pancrustacea) and major supraordinal groups (e.g., Hexapoda, Insecta, Entognatha, Ectognatha, Dicondylia, Apterygota, Pterygota, Paleoptera, Neoptera). Main kinds of characters and phylogenetic schemes are considered.

RESUMEN. La historia de la clasificación de los insectos es analizada desde el punto de vista de sus relaciones externas (e.g., Unirramia, Mandibulata, Atelocerata, Pancrustacea) e internas (e.g., Hexapoda, Insecta, Entognatha, Ectognatha, Dicondylia, Apterygota, Pterygota, Paleoptera, Neoptera). Se consideran las fuentes de caracteres y las posturas filogenéticas que justifican los distintos taxones propuestos.

The last instar larva of Erythrodiplax paraguayensis (Förster) is described and illustrated, based on Iberá (Corrientes, Argentina) specimens. A comparative analysis of all hitherto known larvae from Argentina is provided.

Se describe e ilustra por primera vez al último estadio larval de Erythrodiplax paraguayensis (Förster) sobre la base de especímenes recolectados en los esteros del Iberá (Corrientes, Argentina). Se brinda además un análisis comparativo de las larvas de especies citadas en la Argentina.

A species of the Lutzomyia oswaldoi group is recorded from the Valcheta stream basin, Somuncura plateau, Patagonia. It represents the World southermost record of a species of Phlebotominae, apparently supporting the hypothesis about the relictual character of several components of the Somuncura plateau biota, particularly for those species belonging to the Paranaense lineages.