A formal method was developed to determine areas of endemism. The study region is divided into cells, and the number of species that can be considered as endemic is counted for a given set of cells (= area). Thus, the areas with the maximum number of species considered endemic are preferred. This is the first method for the identification of areas of endemism that implements an optimality criterion directly based on considering the aspects of species distribution that are relevant to endemism. The method is implemented in two computer programs, NDM and VNDM, available from the authors.

The idea of an area of endemism implies that different groups of plants and animals should have largely coincident distributions. This paper analyses an area of 1152 000 km2, between parallels 21 and 32°S and meridians 70 and 53°W to examine whether a large and taxonomically diverse data set actually displays areas supported by different groups. The data set includes the distribution of 805 species of plants (45 families), mammals (25 families), reptiles (six families), amphibians (five families), birds (18 families), and insects (30 families), and is analysed with the optimality criterion (based on the notion of endemism) implemented in the program NDM/VNDM. Almost 50% of the areas obtained are supported by three or more major groups; areas supported by fewer major groups generally contain species from different genera, families, or orders. © The Willi Hennig Society 2011.

The Iberá Nature Reserve in northeastern Argentina protects one of the largest freshwater wetlands and reservoirs of species in South America. However, key invertebrate groups such as the ants (Hymenoptera: Formicidae) remain almost unknown. The main objective of this work was to study the ground ant diversity in four main habitats of Iberá: grasslands, savannas, forests, and floating islands. Pitfall traps were used to characterize ground foraging ant assemblages, compare ant diversity among environments, and establish habitat associations. We also used bait traps, manual collections, and Winkler and Berlese extractors on the ground, vegetation, and litter strata to increase the species inventory. In total, 94 species in 30 genera were captured, representing the highest number of species reported from a survey of a protected area of Argentina. The richest genus was Pheidole Westwood with 23 species including three species reported for the first time in Argentina. The most common species was Solenopsis invicta Buren. Overall, the savanna was the richest and most diverse habitat with the highest number of exclusive species and functional groups. The grassland showed the highest number of rare species, but only half of the expected species were captured. The forest showed the lowest ant richness, diversity, and equitability, but one half of the species were exclusive to forest habitat. Generalized myrmicines were predominant and dominant in all habitats. Our findings indicate that habitat specialization could be an important factor determining the organization of ant assemblages in Iberá. The protection of each of these unique and threatened natural habitats of Argentina is needed to ensure the long-term preservation of their exclusive ant species.

The main purpose of this study is to analyze whether areas of endemism can be characterized quantitatively by using insects, which are typically much more poorly sampled than vertebrates or plants. For this, an optimality criterion in the search for endemic areas was used to analyze approximately 1,100 georeferences from 288 species of holometabolous insects found in the study region, the Yungas (a very moist, montane rainforest), located in north-western Argentina. The optimality criterion is implemented with the programs NDM/VNDM, used to evaluate areas of endemism (i.e. a set of cells defined by two or more endemic species). Five grid sizes were used, three square (1°, 0.5°, and 0.25°) and two rectangular (0.25° x 0.5° and 0.5° x 0.25°). In agreement with the traditional biogeographic proposal, the results of the present study indicate that the Yungas can be characterized as a biogeographic unit with its own identity. Twenty six areas related to Yungas have shown 23 species of insects (in 14 families) as endemic, restricted to Yungas environment, and 46 species (in 10 families) as endemic, present in Yungas and surrounding habitats. Our analysis suggests that the use of insects to identify areas of endemism is a powerful tool, even considering the current fragmentary knowledge of these groups in South America. Given that there is no criterion to choose an optimal grid size, the use of different grid sizes is crucial; medium and small sizes are highly recommended because both identify seemingly different patterns. The quantitative method used here is useful to identify areas of endemism, such as disjoint areas or partially overlapping areas, which are difficult to see with other traditional biogeographic methods.

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The aim of this paper is to actualize the taxonomy ofDorymyrmex, by addressing problems at both the genus and the species levels. We also explore the taxonomy and distribution ofDorymyrmexin Colombia. We list, diagnose, and key nine species in the country, including three new species:Dorymyrmex amazonicusn. sp. Cuezzo & Guerrero,Dorymyrmex xerophylusn. sp. Cuezzo & Guerrero, andDorymyrmex tuberosusn. sp. Cuezzo & Guerrero. We provide a detailed description of these new species based on the worker caste and, where possible, other castes. All localities whereDorymyrmexwas collected or cited in the literature were mapped to provide a graphical view of its range.

Recently a new species of bombyliid fly, Marleyimyia xylocopae, was described by Marshall & Evenhuis (2015) based on two photographs taken during fieldwork in the Republic of South Africa. This species has no preserved holotype. The paper generated some buzz, especially among dipterists, because in most cases photographs taken in the field provide insufficient information for properly diagnosing and documenting species of Diptera.

The maintenance of species diversity in modified and natural habitats is a central focus of conservation biology. The Iberá Nature Reserve (INR) protects highly diverse ecosystems in northeastern Argentina, including one of the largest freshwater wetlands in South America. Livestock grazing is one of the major disturbances to these ecosystems; however, its effect on ant diversity is poorly known. The objective of this work was to study the effect of savanna versus grassland and grazing on the structure and composition of subtropical terrestrial ants focusing on the particular response of the native red imported fire ant, Solenopsis invicta Buren. Unbaited pitfall traps were used to capture worker ants in 25 grazed and 20 nongrazed sites. Fifty ant species were collected. The savanna showed more species, individuals, biomass, and functional groups of ants than the grassland. S. invicta was the most frequently captured (61.4%) and numerically dominant species; however Camponotus punctulatus punctulatus Mayr showed the highest biomass. Grazing simplified vegetation structure in both habitats, but its impact on vegetation seemed only to promote a higher total biomass especially in the grassland, and/or functional groups, favoring occurrence of hot-climate specialists in the savanna. This study revealed that habitat type strongly affected the organization of the terrestrial ant assemblages at the INR. However, as in other studies, we did not find clear evidence that habitat modification by grazing significantly affected terrestrial ant assemblages. The weak grazing influence could be the consequence of the short enclosure time as to recover the original ant communities, the differential response of ant species to habitat type, and/or the resilience of ants.