Por Sergio Ricardo Andena (Professor Adjunto. Museu de Zoologia, Universidade Estadual de Feira de Santana. Feira de Santana, Bahia, Brazil).

The Brazilian semiarid region comprises an area of about 900.000 km2 (10% of Brazilian Territory) along the states located in the Northeastern of the country. The majority of the semiarid region is covered by the Caatinga (drylands) ecoregion, being one of the most diverse landscapes in Brazil, both in geomorphological and vegetation types. In general, Caatinga can be characterized by thorny trees that shed their leaves seasonally, also by thick- stemmed plants, grasses and brushes. It´s the driest region of Brazil, with 700mm of rainfall per year. For a long time dry regions of Brazil were considered of low diversity and, since them, little attention has been given. Besides, Caatinga is one of the most overexploited bioma of Brazil, being devasted for centuries; the region that holds only few universities and biological collections, and less known in terms of its biodiversity. The subfamily Polistinae (paper wasps) is the most diverse group of social wasps, both in terms of species richness (about 900 species described) and morphological and behavioral diversity. In Brazil three tribes are found, Polistini – cosmopolitan, except New Zeland; Mischocyttarini – from Canada to North of Argentina; and Epiponini – from southwester of US to Argentina. These tribes are abundant in tropics and easily found in urban areas. In Brazil they are known as vespas, cabas or marimbondos. Unfortunately, the fauna of social wasps, as well as other arthropods, in Caatinga is poorly known and only few works were carried out in the region, some of them more than one century ago. Here we present the first attempt to describe de fauna of social wasps in Caatinga, which consisted in: field work in several localities, search for species deposited in collections and literature. A total of 85 species of social wasps were recorded in Caatinga, being 50 for Epiponini; 18 for Mischocyttarini and 17 for Polistini. Bahia is the best surveyed state with 71 species recorded, followed by Ceará, Pernambuco, Piauí, Paraíba, Rio Grande do Norte and Alagoas. There is no record of social wasps in the state of Sergipe. Except Bahia, the data available for the remaining states are scatted and imprecise. Even being subsampled, the richness of social wasps place the caatinga in the fourth place, comparing with other Brazilian biomas. It may change the view that dry biomas do not have high diversity. Also, more researches must be stimulated and preservation policies implanted in this important bioma of Brazil.