The Ground-Dwelling Ant Fauna from a Cerrado Reserve in Southeastern Brazil: Vegetation Heterogeneity as a Promoter of Ant Diversity.

Ants represent one of the most diverse and ecologically important group of insects in tropical ecosystems, including in highly threatened ones such as the Brazilian Cerrado. Yet, a detailed understanding of the species diversity and composition of local Cerrado ant assemblages is lacking in many cases. Here we present the results of a comprehensive ant inventory performed within a region of the Cerrado (in São Paulo state) where most of the original vegetation has already been lost and where few conservation units exist. We performed consecutive surveys of the ant fauna that forage on the ground in replicated plots established in open savanna (campo sujo), dense savanna (cerrado sensu stricto), and forest (cerradão). Our surveys, with an estimated sample coverage of 99.4%, revealed a total of 219 species of ants from 60 genera, of which 36.1% were found in all the three vegetation types and 29.7% in just one. Rarefied species richness did not differ between vegetation types, but species composition differed markedly, especially between the two savannas in one hand and the forest in the other. Several species (60.1% of the 128 species analyzed) were significant "indicator" species due to their strong association with a given vegetation type. Overall, our findings reinforce the idea that habitat heterogeneity enhances ant diversity and that the mosaic of vegetation types that characterizes the Cerrado biome is one of the main factors explaining the elevated number of species that can be found at relatively small scales.

ATLANTIC ANTS: a data set of ants in Atlantic Forests of South America.

Ants, an ecologically successful and numerically dominant group of animals, play key ecological roles as soil engineers, predators, nutrient recyclers, and regulators of plant growth and reproduction in most terrestrial ecosystems. Further, ants are widely used as bioindicators of the ecological impact of land use. We gathered information of ant species in the Atlantic Forest of South America. The ATLANTIC ANTS data set, which is part of the ATLANTIC SERIES data papers, is a compilation of ant records from collections (18,713 records), unpublished data (29,651 records), and published sources (106,910 records; 1,059 references), including papers, theses, dissertations, and book chapters published from 1886 to 2020. In total, the data set contains 153,818 ant records from 7,636 study locations in the Atlantic Forest, representing 10 subfamilies, 99 genera, 1,114 ant species identified with updated taxonomic certainty, and 2,235 morphospecies codes. Our data set reflects the heterogeneity in ant records, which include ants sampled at the beginning of the taxonomic history of myrmecology (the 19th and 20th centuries) and more recent ant surveys designed to address specific questions in ecology and biology. The data set can be used by researchers to develop strategies to deal with different macroecological and region-wide questions, focusing on assemblages, species occurrences, and distribution patterns. Furthermore, the data can be used to assess the consequences of changes in land use in the Atlantic Forest on different ecological processes. No copyright restrictions apply to the use of this data set, but we request that authors cite this data paper when using these data in publications or teaching events.

Ants associate with microlepidoptera galleries in leaves of Acrostichum danaeifolium Langsd. & Fisch

ABSTRACT Acrostichum danaeifolium, a Neotropical fern, occurs preferentially in marshy areas or at the margins of lakes and mangroves. Microlepidoptera larvae burrow through the petioles of the fern, preferentially on the non-expanded leaves. The galleries in the petiole create a new microhabitat, harboring a rich fauna of arthropods. The aim of the present study was to assess the richness of ants associated with its petiole. The study was conducted in a population of A. danaefolium from the Atlantic Forest in Rio de Janeiro state, Southeastern Brazil. Six collections were carried out every two months (2009-2010), three in the dry and three in the rainy season. The leaves were divided into three development stages: non-expanded leaves (NEL), expanded leaves (EL) and senescent leaves (SL). Seven leaves from each phase were randomly collected from seven individuals. A total of fifteen ant species were recorded. The species with the highest frequency and density in fern petioles were Camponotus crassus and Crematogaster curvispinosa. The highest ant richness and abundance was found in senescent leaves. The high number of ants found in the petioles of Acrostichum danaefolium qualifies it as a potential key species in the marshes and flooded areas where it occurs.

Ants associated with fronds of the tropical bracken fern Pteridium esculentum subsp. arachnoideum / Formigas associadas às frondes da samambaia Pteridium esculentum subsp. arachnoideum

Abstract: Pteridium is a cosmopolitan genus of ferns that possess nectaries on its fronds (fern leaves), thereby attracting ants. Foliar (or extrafloral) nectaries are nectar-producing glands that are not related to pollination, but rather attract ants and other arthropods. Foliar nectaries are found in 101 fern species, belonging to 11 genera and six families. The aim of the study is to characterize the community of ants that visit the fronds of Pteridium esculentum subsp. arachnoideum, as well as daily and seasonal ant abundance in different frond development stages. The study was conducted in the Atlantic Forest of Rio de Janeiro state, Brazil. Bimonthly collections were established, where 30 expanding fronds and 30 fully expanded fronds were randomly marked. In each 1-hour shift starting at 8:30 am and ending at 5:30 pm, the fronds were observed for the presence of ants. Thirty three ant species were recorded on the Pteridium esculentum subsp. arachnoideum fronds, distributed into six subfamilies and 13 genera. The most abundant species were Solenopsis sp.1 and Ectatomma tuberculatum. Eight ant species were observed foraging the nectaries of tropical bracken fern fronds. Ectatomma tuberculatum has been observed feeding on the nectaries and patrolling the fronds. Ant activity peak was on mid-day during the rainy season. The tropical bracken fern Pteridium esculentum subsp. arachnoideum has a rich (the highest recorded until now on Pteridium species) and diverse ant community on its fronds, mainly on the expanding fronds. The presence of generalist predatory ants (Ectatomma tuberculatum and Solenopsis sp.1) during the entire study period suggests a positive interaction between ants and Pteridium esculentum subsp. arachnoideum.

Resumo: Pteridium é um gênero cosmopolita de samambaias que possui nectários em suas frondes (folhas de samambaias), atraindo formigas. Nectários foliares (ou extraflorais) são glândulas produtoras de néctar que não estão relacionadas com a polinização, mas podem atrair formigas e outros artrópodes. Nectários foliares já foram registrados em 101 espécies de samambaias, pertencentes a 11 gêneros e seis famílias. O objetivo do estudo é caracterizar a comunidade de formigas que visitam as frondes de Pteridium esculentum subsp. arachnoideum, bem como a abundância diária e sazonal das formigas em diferentes estágios foliares. O estudo foi realizado na Mata Atlântica do estado do Rio de Janeiro, Brasil. Foram estabelecidas coletas bimestrais, onde foram marcadas aleatoriamente 30 frondes em expansão e 30 frondes totalmente expandidas. Em cada turno de 1 hora com início às 8h30 e término às 17h30, as frondes marcadas foram observadas quanto à presença de formigas. Trinta e três espécies de formigas foram registradas nas frondes do Pteridium esculentum subsp. arachnoideum, distribuídas em seis subfamílias e 13 gêneros. As espécies mais abundantes foram Solenopsis sp.1 e Ectatomma tuberculatum. Foram registradas oito espécies de formigas forrageando os nectários foliares da samambaia. Ectatomma tuberculatum foi observada se alimentando nos nectários e patrulhando as frondes. As formigas tiveram o pico de atividade ao meio-dia e na estação chuvosa. A samambaia tropical Pteridium esculentum subsp. arachnoideum tem uma elevada riqueza (a maior já registrada até o momento para espécies de Pteridium) e diversidade de formigas em suas frondes, com maior frequência nas frondes não totalmente expandidas. A presença de formigas predadoras generalistas (Ectatomma tuberculatum e Solenopsis sp.1) durante todo o período de estudo sugere uma interação positiva entre as formigas e Pteridium esculentum subsp. arachnoideum.

Ants of the State of Par, Brazil: a historical and comprehensive dataset of a key biodiversity hotspot in the Amazon Basin.

The state of Par in northern Brazil is located entirely within the Amazon Basin and harbors a great diversity of landscape and vegetation types that support high levels of biodiversity. Here, we provide a comprehensive inventory of ant species and their distribution in Par. This regional list is based on an extensive review of species records from published and unpublished sources covering a period of 134 years (18862020) and includes the five most representative ant collections in Brazil. In total, we documented 12 subfamilies, 90 genera and 753 ant species, including 97 species recorded for the first time in Par and 12 species newly reported in Brazil. Sampling effort across the state is highly uneven, and most records may be associated with research areas near the state capital, mining areas, hydroelectric dams, and research field stations run by the state or universities. In addition, our results suggest a strong bias in ant collection in Par in terms of proximity of sampled sites to access routes, such as roads and rivers. We also found that species records were highly unevenly distributed based on areas of endemism within the Amazon, vegetation type, and protected areas within the state. Ant surveys are still lacking from most protected areas of Par, and further sampling is urgently needed in view of the current trend of expansion of major infrastructure projects and natural resource harvesting within protected areas of Par. Our database represents an extremely valuable and rich source of information for further studies on ant biodiversity and conservation in the Amazon Basin.

Patterns of Ant Diversity in the Natural Grasslands of Southern Brazil.

In the south of Brazil, grasslands are naturally widespread over two different biomes, the Pampa in the southernmost region and within the Atlantic Forest in the northern portions. The natural grasslands of the state of Paraná comprise a very particular physiognomy composed of two distinct formations: the Campos Gerais and the grasslands of the southwest. The first is located in the edge of the second plateau of Paraná state, comprising a great diversity of environments. The grasslands of the southwest are more homogeneous, with a continuous herbaceous stratum dominating the landscape. In this context, the aim of this study was to evaluate the patterns of species richness and composition of ants, an ecologically prominent group, along the natural grasslands of Paraná. We also intended to compare the faunal similarity between the two different grassland formations. For that, four different Conservation Unities were sampled along a latitudinal gradient. A remarkable total of 245 ant species was recorded, and the results indicate that species richness decreases as latitude increases along the grasslands of Paraná. There were clear differences in species composition between these two grasslands formations, given the significative number of endemic species in each of these two grassland formations. Ten species were recorded for the first time in the state of Paraná, of which three also for the first time in the Southern Region of Brazil. Overall, our study contributes to a better understanding about the diversity and composition of ant communities in subtropical grasslands.

Revisiting the ideas of trees as templates and the competition paradigm in pairwise analyses of ground-dwelling ant species occurrences in a tropical forest

Abstract A challenge for studies on the organization of ant assemblages in forest ecosystems is to disentangle the causal effects of species occurrences. The structural and functional attributes of trees can act as environmental filters for ground-dwelling ant species influencing resource availability and the microclimate. The biotic interactions, especially competition, can work together with plant characteristics influencing ant species occurrences. To test the importance of tree traits and species interactions on co-occurrence patterns of ants, we collected ground-dwelling ants, with pitfalls and litter sampling, beneath the canopies of four tree species during the rainy and dry seasons in a restored forest. We used five predictors (tree identity, crown size, trunk circumference, litter depth, and leaves density) to model the presence probabilities of ants . Hence, we applied habitat constrained null models in pairwise analyses to disentangle the causal effects of ants co-occurrences. The random pattern predominated in the assemblages, making up 96% of all possible species pairs combinations. Overall, 50% of the species pairs that showed nonrandomness in the ant occurrences were interpreted as resulting from environmental filters, 36% as negative associations and 14% as positive associations. Additionally, we found that the effects of season and the sampling technique on the ant assemblages were also important. We suggest that the ideas of the trees as templates and the paradigm of competition are both useful for understanding pairwise occurrence patterns in ant assemblages, and can be tested using tree traits as predictors in ant species distribution models for running constrained null models.

A taxonomic study of the Brazilian turtle ants (Formicidae: Myrmicinae: Cephalotes)

ABSTRACT We revise the taxonomy of species of the ant genus Cephalotes occurring in Brazil. Sixty-four species are recognized, distributed in 14 species groups. Five species are described as new: Cephalotes gabicamacho new species, Cephalotes marycorn new species, and Cephalotes monicaulyssea new species (angustus group); Cephalotes liviaprado new species (fiebrigi group); and Cephalotes mariadeandrade new species (pinelii group). The soldier and gyne of C. adolphi (angustus group), and the gyne and male of C. nilpiei (pinelii group) are described for the first time. Cephalotes marginatus is synonymized under C. atratus. The bruchi and the laminatus species groups are synonymized under fiebrigi and pusillus groups, respectively. The new species group manni is proposed, derived from the basalis species group. Distribution maps for each species in Brazil are provided. In addition, we provide an illustrated morphological glossary for the genus and illustrated identification keys for workers and soldiers for species groups and for all Brazilian species.

Accessing the subterranean ant fauna (Hymenoptera: Formicidae) in native and modified subtropical landscapes in the Neotropics / Avaliação da mirmecofauna subterrânea (Hymenoptera: Formicidae) em paisagens nativas e modificadas na região subtropical do Neotrópico

Abstract: Several studies have characterized and delimited subterranean ant assemblages. Soil extraction, one of the methods employed to access this fauna, employs the removal of monoliths. One of the most widely used methods for the extraction of soil sampling is called TSBF (developed by the Tropical Soil Biology and Fertility Programme). This method provides relevant data about the species associated with the soil. In the present study we characterized assemblages of subterranean ants using the TSBF method in different subtropical areas of the Neotropics. We considered two sampling designs in different localities. The first design resulted in 315 TSBF samples obtained from layers at distinct depths. The second design resulted in 270 TSBF samples and 270 epigaeic pitfall trap samples. This material was used to delimit the species that occur exclusively in the subterranean stratum (TSBF) and that are not found on the soil surface. A total of 281 species were recorded. Of these, 57 can be considered subterranean, based on their occurrence in subterranean strata. We also verified that the highest occurrence of ants was in the first 10 cm of soil depth. Due to the importance of using methods that efficiently extract the subterranean ant fauna in studies, we suggest the TSBF method should be used to sample ants or to associate this method with epigaeic pitfall traps to delimit strictly subterranean assemblages in specific community stratification studies.

Resumo: Vários estudos têm caracterizado e delimitado assembleias de formigas subterrâneas. A extração de solo, um dos métodos utilizados para amostragem dessa fala, implica na remoção de monólitos. Um dos métodos mais utilizados na extração de monólitos é chamado TSBF (desenvolvido pelo Programa Tropical Soil Biology and Fertility). Esse método fornece dados extremamente relevantes sobre as espécies associadas ao solo. No presente estudo, nós caracterizamos as assembleias de formigas subterrâneas usando o método TSBF em diferentes áreas subtropicais do Neotrópico. Utilizamos dois delineamentos amostrais distintos. O primeiro delineamento resultou em 315 amostras de TSBF obtidas a partir da estratificação do solo. O segundo resultou em 270 amostras de TSBF mais 270 provenientes de armadilhas pitfall epigeicas. Esse material foi utilizado para delimitar espécies que ocorrem exclusivamente no estrato subterrâneo (TSBF) e não são encontradas na superfície do solo. Registramos um total de 281 espécies. Destas, 57 podem ser consideradas subterrâneas (baseado na ocorrência no respectivo estrato). Também verificamos que a maior ocorrência de formigas se deu nos primeiros 10 cm de profundidade. Devido à importância do uso de métodos que coletem eficientemente formigas subterrâneas, sugerimos o uso do método TSBF em estudos de estratificação de comunidades ou sua associação a armadilhas do tipo pitfall epigeica para delimitar assembleias estritamente subterrâneas.

New distribution records of the savanna specialist fungus-farming ant Cyatta Sosa-Calvo et al. (Hymenoptera: Formicidae: Myrmicinae).

BACKGROUND: The fungus-farming ant genus Cyatta (Formicidae: Myrmicinae) is represented by a single species, C. abscondita Sosa-Calvo et al., known from a few localities in Brazil (in the states of Ceará, Minas Gerais, São Paulo and the Distrito Federal), and a single locality in the Misiones province, Argentina. Cyatta is known to occur predominantly in savanna habitats and occasionally in the transition zones between the Atlantic Forest and Cerrado. NEW INFORMATION: The new records reported here significantly expand the previously known distribution of Cyatta abscondita and provide further support for the intimate relation between this species and the savannas of South America. We report the first occurrence of the genus in southern Brazil (Paraná state) and the westernmost occurrence (Bolivia) of Cyatta abscondita, which extend its distribution approximately 1450 km to the west. Finally, we discuss the importance of mapping inconspicuous species in order to develop strategies for protecting endangered areas and to increase our understanding of the evolutionary history of organisms and biomes.

Description of the immatures of the ant, Myrmelachista catharinae.

The Neotropical ant genus Myrmelachista Roger comprises 69 described species and subspecies, and still is a poorly studied group. Larvae play a paramount role in colony nutrition in social hymenopterans and bear considerable value in the reconstruction of group phylogenies, however, they are generally neglected. Larvae of different instars of Myrmelachista catharinae Mayr (Hymenoptera: Formicidae) are herein described in detail by light and scanning electron microscopy. The number of larval instars was estimated as three based on the frequency distribution of maximum head capsule widths. The described larvae confirmed some traits typical of the genus: general shape of body and mandibles, general aspect and distribution of body hairs, and the number of sensilla on the palps and galea. Differently from other Myrmelachista larvae previously described, M. catharinae presented two distinct kinds of second instars, some additional types of body hairs, different number of antennal sensilla, and a distinct labrum shape. M. catharinae presented ten pairs of spiracles, which is the first record for this genus.

Rediscovery of the putatively extinct ant species Simopelta minima (Brandão) (Hymenoptera, Formicidae), with a discussion on rarity and conservation status of ant species / Redescoberta da espécie supostamente extinta de formigas, Simopelta minima (Brandão) (Hymenoptera, Formicidae), com uma discussão sobre raridade e estado de conservação de espécies de formigas

Simopelta minima (Brandão, 1989) was originally described based on four workers collected in soil samples from a small cocoa plantation in Ilhéus, state of Bahia, northeastern Brazil. In the subsequent years after the description, this cocoa plantation was eliminated and the species was then considered extinct by the Brazilian environmental institutions. The recent rediscovery of S. minima workers in subterranean pitfall trap samples from Viçosa, state of Minas Gerais, southeastern Brazil, over 1.000 km distant from type locality, suggests that the rarity and vulnerability status of some ant species may be explained by insufficient sampling of adequate microhabitats, in time and space.

Simopelta minima (Brandão, 1989) foi originalmente descrita com base em quatro operárias coletadas em amostras de solo provenientes de uma pequena plantação de cacau localizada em Ilhéus, Estado da Bahia, nordeste do Brasil. Nos anos seguintes à descrição, esta pequena plantação de cacau foi eliminada e a espécie passou a ser considerada extinta pelas instituições ambientais brasileiras. Recentemente foram coletadas operárias de Simopelta minima em amostras de armadilhas subterrâneas do tipo "pitfall", em Viçosa, Estado de Minas Gerais, sudeste do Brasil, a mais de 1.000 km de distância da localidade tipo. Esta redescoberta sugere que o status de raridade e/ou vulnerabilidade atribuído a algumas espécies de formigas pode ser explicado pela amostragem insuficiente de microhabitats adequados, no tempo e no espaço.