The new records of C. abscondita presented here come from surveys conducted within the ongoing project entitled “Rede de Pesquisa Biota do cerrado (RPBcerrado 6) - Isoptera e Hymenoptera” (project CNPq 457407/2012-3), coordinated by HLV. The project seeks to increase knowledge about the biodiversity of Hymenoptera and Isoptera in the Cerrado biome and identify the processes that generate and maintain their diversity in a biome highly threatened by human activities.

Samples were collected in 29 different localities of Cerrado, comprising the entire extension of the biome. In each collection site three transects of 400 m each were installed, separated by a distance of about 1 km (Vasconcelos et al. 2014). At every 20 m of the transect the nearest tree (height > 2.5 m) was marked and four arboreal pitfall traps were installed in different parts of the canopy. In addition, four pitfall traps were placed in the soil around the tree forming a 2 x 2 m grid with the tree trunk representing its center.

Ants were stored in 80% ethanol and processed in the Laboratório de Ecologia de Insetos Sociais of the Universidade Federal de Uberlândia (UFU). Vouchers are deposited in the Museu de Biodiversidade do Cerrado (MBC), Uberlândia, Minas Gerais; in the Padre Jesus Santiago Moure Entomological Collection (DZUP) of the Universidade Federal do Paraná, Curitiba, Paraná, Brazil; and in the Museu de Zoologia da Universidade de São Paulo (MZSP), São Paulo, SP, Brazil.

One of the sampling points of the project was the “Parque Estadual do Cerrado (hereinafter Cerrado State Park, or CSP), located near the town of Jaguariaíva, Paraná state (24°10'04,7"S, 49°40'05,5"W), at the southern boundary of the Cerrado biome in Brazil. Ant collections in the CSP were also conducted within the project “Formigas (Hymenoptera, Formicidae) e a conservação dos campos naturais paranaenses: uma abordagem ecológica e taxonômica” (project CNPq 459353/2014-4), coordinated by RMF. This project aims to sample the ant fauna of grasslands in the Paraná state following the sampling protocol mentioned above.

In addition to the CSP, new records of Cyatta come from four other Cerrado sites: Parque Estadual da Serra de Caldas (Serra de Caldas State Park, SCN), in Caldas Novas, Goiás (17°47'07,1"S, 48°40'07,5"W); Parque Estadual da Serra de Ricardo Franco (Serra Ricardo Franco State Park, SRF) (Fig. 2), in Vila Bela da Santíssima Trindade, Mato Grosso (14°55'07,3"S, 60°04'25,0"W); Estação Ecológica de Santa Bárbara (Santa Barbara Ecological Station, SBE), in Águas de Santa Bárbara, São Paulo (22°49'12,3"S, 49°13'07,3"W).

Figure 2.  

Parque Estadual da Serra de Ricardo Franco (Serra Ricardo Franco State Park, SRF), in Vila Bela da Santíssima Trindade, Mato Grosso state (14°55'07,3"S, 60°04'25,0"W). Photo by Jonas Maravalhas.

For all the aforementioned localities the predominant habitat is the Cerrado sensu stricto, an arboreal open woodland characterized by the presence of small trees with a canopy height of less than seven meters, shrubs, and abundant ground layer dominated by grasses (Gottsberger and Silberbauer-Gottsberger 2006). Cerrado soil is typically a red-yellow latosol, largely composed of well-drained and nutrient-poor quartz sand with a moderate clay content (Bramorski et al. 2012). The typical Cerrado climate is characterized by a marked dry season from May to September and mean annual temperature and precipitation of 23°C and ~1420 mm, respectively (Gottsberger and Silberbauer-Gottsberger 2006).

We also present here the first records of Cyatta from Cerrado areas of Bolivia, based on males collected at the Reserva Privada del Patrimonio Natural Potrerillos del Guenda (RNPG) in Santa Cruz de la Sierra (17°40' S, 63°27'W), and deposited in the University of California at Davis (UCDC) and at the Smithsonian Institution, Washington D.C (USNM).

The distribution map was generated using Quantum-Gis 2.12 based on the data from previous studies that recorded C. abscondita (Sosa-Calvo et al. 2013, Camacho and Vasconcelos 2015, Ramos et al. 2016), and our present results.

Five new records of this rarely collected ant genus were added to the nine previously known, totaling 14 localities where Cyatta abscondita has been found, raising by more than 50% the number of occurrence sites for Cyatta. We report 15 specimens for the new occurrence sites, five in CSP, five in RNPG, two in SBE, two in SRF and one in SCN. All the newly collected specimens were captured in pitfall traps placed on the ground, except by the Bolivian specimens (RNPG) for which the collection method is unknown. The fact that such a small amount of workers was sampled from 6,960 pitfall traps installed in the soil of the 29 Cerrado localities of the project highlights the elusive nature of this species.

The southernmost record for this genus is the province of Misiones, Argentina (Ramos et al. 2016); however, the record presented here for the CSP in Jaguariaíva, Paraná, represents the first record of Cyatta for southern Brazil (Fig. 3). We emphasize the importance of this record in the Cerrado State Park, which carries an inestimable importance for biodiversity conservation in the region. This park represents the southern limit of the Cerrado, and is the only fragment of this biome legally protected in southern Brazil (Linsingen et al. 2006).

Figure 3.  

Parque Estadual do Cerrado (Cerrado State Park, CSP), in Jaguariaíva, Paraná state (24°10'04,7"S, 49°40'05,5"W). Photo by Rodrigo Feitosa.

The westernmost limit of the genus distribution was previously represented by specimens collected in the municipality of Sales, São Paulo state. The males collected in RNPG, Santa Cruz de la Sierra, Bolivia, extend the western limit of the known distribution by an impressive 1450 kilometers.

All the sites where Cyatta was collected are savannas or transition zones between semi-deciduous Atlantic Forest and Cerrado (Table 1). These new records not only corroborate previous observations regarding the distribution of C. abscondita in savannas, but broaden its potential distribution over most of this biome. Although it was recently collected in a subtropical semi-deciduous native forest in Argentina (Ramos et al. 2016), it seems reasonable to assume that Cyatta abscondita is an inconspicuous though broadly distributed element of the so called South American dry diagonal (Fig. 4), which includes the savanna lands of northeastern and central Brazil (Caatinga and Cerrado, respectively), and the Chaco areas of Paraguay and Argentina (Prado and Gibbs 1993).

Figure 4.  

Distribution map for Cyatta abscondita.

It is essential to improve our knowledge about the natural history and geographic distribution of life forms to develop relevant conservation strategies for ants (Guenard et al. 2012). This is especially true in ecosystems were the presence of endemic species is threatened due to the rapid loss of habitat resulting from unsustainable human exploitation, i.e. the biodiversity hotspots (Myers et al. 2000). The Brazilian Cerrado is one such hotspot, with more than four thousand species of endemic plants and more than one hundred species of endemic vertebrates (Myers et al. 2000). Over 60% of the original Cerrado distribution is still covered by natural vegetation, but in an asymmetrical fashion, with most remnants located in the northern region (Sano et al. 2010). Unfortunately, only about 3.1% of the original Cerrado vegetation is under strict environmental protection (M.M.A 2016), a situation for concern.

Another biome of occurrence for Cyatta, the Brazilian Caatinga, is even less protected than the Cerrado (Silva et al. 2004). The discovery of Cyatta abscondita in Cerrado areas of western Brazil and Bolivia, suggests that this species may also occur in poorly explored habitats of South America, as the Chaco, for example (Bucher 1982). Our study suggests that increasing the search for elusive and inconspicuous species may lead to discoveries that can alter our fundamental understanding of the evolutionary history of organisms and biomes.