Patterns of diversity and abundance of fungus-growing ants (Formicidae: Attini) in areas of the Brazilian Cerrado Padrões de diversidade e abundância de formigas cultivadoras de fungo (Formicidade: Attini) em áreas do Cerrado Brasileiro

Fungus-growing ants (tribe Attini) are characteristic elements of the New World fauna. However, there is little information on the patterns of diversity, abundance, and distribution of attine species in their native ecosystems, especially for the so-called "lower" genera of the tribe. A survey of attine ant nests (excluding Atta Fabricus, 1804 and Acromyrmex Mayr, 1865) was conducted in a variety of savanna and forest habitats of the Cerrado biome near Uberlândia, Brazil. In total, 314 nests from 21 species of nine genera were found. Trachymyrmex Forel, 1893 was the most diverse genus with 10 species. Eighteen species were found in the savannas, including Mycetagroicus cerradensis Brandão & Mayhé-Nunes, 2001, a species from a recently-described genus of Attini, whereas in the forests only 12 species were found. Forest and savannas support relatively distinct faunas, each with a number of unique species; the species present in the forest habitats did not represent a nested subset of the species found in the savannas. Furthermore, although many species were common to both types of vegetation, their abundances were quite different. The density of attine nests is relatively high at some sites, exceeding an estimated 4,000 nests per hectare. In this sense, attine ants can be regarded as prevalent invertebrate taxa in the Brazilian Cerrado.<br>As formigas cultivadoras de fungos (tribo Attini) são exclusivas da fauna do Novo Mundo. Entretanto, existem poucas informações sobre os padrões de diversidade, abundância e distribuição das espécies de Attini em seus ecossistemas nativos, em especial para os gêneros menos derivados desta tribo. Um levantamento de ninhos de Attini (excluindo Atta Fabricius, 1804 e Acromyrmex Mayr, 1865) foi realizado em diversos ambientes savânicos e de floresta do bioma Cerrado próximos à Uberlândia, Brasil. Encontramos 314 ninhos de 21 espécies pertencentes a nove gêneros da tribo. Trachymyrmex Forel, 1893 foi o gênero mais diverso, com 10 espécies. Encontramos 18 espécies na savana, incluindo Mycetagroicus cerradensis Brandão & Mayhé-Nunes, 2001, uma espécie de um gênero de Attini recentemente descrito, enquanto que nas áreas de floresta registramos somente 12 espécies. As savanas e florestas apresentaram faunas relativamente distintas, com espécies exclusivas de cada tipo de vegetação; as espécies presentes nas florestas não representaram um subconjunto das espécies encontradas nas savanas. Além disso, apesar de muitas espécies terem sido comuns a ambos os tipos de vegetação, suas abundâncias foram muito diferentes. A densidade estimada de ninhos de Attini foi relativamente alta em alguns locais, ultrapassando 4.000 ninhos por hectare. Neste sentido, as formigas da tribo Attini podem ser consideradas como invertebrados predominantes no Cerrado brasileiro

Caracterização de ninhos e atividade forrageadora de Trachymyrmex fuscus Emery (Hymenoptera, Formicidae) em plantio de eucalipto Caracterization of nest and foraging activity of Trachymyrmex fuscus Emery (Hymenoptera, Formicidae) in Eucalyptus stand

<abstract language="eng">Seven nests of T. fuscus Emery, 1834 have been studied for their structure. These nests, which opened at the soil surface, had two to four chambers located one above the other. Externally all of these nests presented a heap of brownish-yellow debris that was constituted basically by remains of vegetable material. The total nest population was, on average, 1,048 individuais. The diel pattern of foraging of this species was studied for four consecuti ve months on two nests. This activity occurred predominantly in the night period, and the workers transported, mainly, dry vegetation to the nest

Simple does not mean poor: grasslands and forests harbor similar ant species richness and distinct composition in highlands of southern Brazil

Several studies addressed ant communities in the dense Atlantic Forest that runs along the Brazilian coast. However, comparatively little is known about the mixed forests and grasslands that occur in the southern range of the Atlantic Forest domain. In this study we performed the first standardized assessment of ants in the forest- grassland mosaic found in the highlands of the state of Santa Catarina. We aimed to investigate and compare ant richness and composition between mixed forests and grasslands in the main mountain range of south Brazil. Ants were collected in two years with ground pitfalls, tree pitfalls and litter samples. Sixty ant species were recorded, resulting in 22 new records for “Planalto Serrano” region and three for the state of Santa Catarina: Eurhopalothrix depressa , Pheidole radoszkowskii and Wasmannia williamsoni . There was significant dissimilarity in ant species composition between grasslands and forests, but no difference in ant species richness, even considering the higher number of strata in mixed forests. Similar richness and low number of arboreal species suggest that this ant community is structured similarly to temperate ones. Both habitats presented a large proportion of exclusive species. The fact that species composition between grassland and forest areas differed, coupled with the similarity in species richness between habitats and the record of new ant species for the region, calls for strong conservation efforts in grasslands of southern Brazil, which still are little protected by conservation areas