Discovery of the termite specialist ant genus Centromyrmex, Mayr 1866 (Hymenoptera: Formicidae: Ponerinae) for the Guiana Shield

The ponerine ant genus Centromyrmex is recorded for the first time in French Guiana. The specimens reported here were collected by the SEAG (Société Entomologique Antilles-Guyane) team in the commune of Saül, French Guiana. The ants were collected in a region of Amazon Forest with flight interception traps. Two out of the three species currently recognized for the genus in South America were here recorded in French Guiana, Centromyrmex alfaroi and Centromyrmex gigas. In total, 24 specimens were collected, all represented by alate queens. This record expands the knowledge about the distribution of this rarely collected genus and reinforces the importance of alternative sampling techniques for collecting cryptobiotic ants and unknown alate forms.

First standardized inventory of ants (Hymenoptera: Formicidae) in the natural grasslands of Paraná: New records for Southern Brazil

Despite the large number of studies investigating ant diversity in Brazilian biomes, no ant-related studies have been carried out in Campos Gerais, a grassland physiognomy in Paraná state. The present study is the first inventory of the ant fauna in one of the few conservation units protecting the Campos Gerais landscape, the Guartelá State Park (PEG). Sixty samples were collected from different habitats within PEG using pitfall traps. Qualitative samples of leaf litter were collected from forest fragments and submitted to Winkler extractors. In addition, manual qualitative sampling was carried out in the various physiognomies within the PEG. A total of 163 species was collected and sorted into 43 genera and nine subfamilies. Five genera and 28 species were recorded for the first time in the state of Paraná. Out of these, 17 species were also recorded for the first time in the Southern Region of Brazil and two were recorded for the first time to the country. The significant species richness in the PEG and the high number of new records is a strong sign of this ecosystem’s potential to reveal taxonomic novelties. These results suggest that PEG, and the Campos Gerais as a whole, should be the target of greater conservation efforts to preserve native remnants

First standardized inventory of ants (Hymenoptera: Formicidae) in the natural grasslands of Paraná: New records for Southern Brazil

Abstract Despite the large number of studies investigating ant diversity in Brazilian biomes, no ant-related studies have been carried out in Campos Gerais, a grassland physiognomy in Paraná state. The present study is the first inventory of the ant fauna in one of the few conservation units protecting the Campos Gerais landscape, the Guartelá State Park (PEG). Sixty samples were collected from different habitats within PEG using pitfall traps. Qualitative samples of leaf litter were collected from forest fragments and submitted to Winkler extractors. In addition, manual qualitative sampling was carried out in the various physiognomies within the PEG. A total of 163 species was collected and sorted into 43 genera and nine subfamilies. Five genera and 28 species were recorded for the first time in the state of Paraná. Out of these, 17 species were also recorded for the first time in the Southern Region of Brazil and two were recorded for the first time to the country. The significant species richness in the PEG and the high number of new records is a strong sign of this ecosystem’s potential to reveal taxonomic novelties. These results suggest that PEG, and the Campos Gerais as a whole, should be the target of greater conservation efforts to preserve native remnants

First survey of the ants (Hymenoptera, Formicidae) of Piauí: filling a major knowledge gap about ant diversity in Brazil

Piauí, a Brazilian Northeast state, has been considered one of the most important regions for the presence of new taxa in ants globally, especially considering the ecosystems’ diversity formed by the transition of the three biomes in the state, the Cerrado, Caatinga and the Atlantic Forest. Despite the recent increase in studies of ant diversity in the Neotropical region, Piauí still represents a major knowledge gap regarding its ant fauna. Therefore, this study aimed to increase the knowledge about the ant fauna of the state by generating a list of species with data obtained from the literature, online repositories and collection expeditions to the Serra da Capivara and Serra das Confusões National Parks. A total of 152 species in 52 genera and nine subfamilies were registered from 24 localities in Piauí. Fifty-eight out the 152 species recorded represent new records for the state, eight are new records for the Brazilian Northeast Region, and one consists of a new record for the country. Eleven species are here recognized as new for science. Considering the field expeditions carried out here, this work represents the first standardized study for the ant fauna of Piauí. The species list presented considerably exceeds the current number of species registered for the state so far. From the present 48 records, the number of species for Piauí raises to more than 150 with a tendency to increase with the accomplishment of future field endeavors and advances in the study of the local ants

Evidences of Batesian Mimicry and Parabiosis in Ants of the Brazilian Savannah

Despite the numerous records of ant-mimicking arthropods, reports of ant species that are mimics among themselves are still rare. In the savannah of central Brazil we found two ant species that are remarkably similar in color pattern and body size, Pseudomyrmex termitarius and Camponotus blandus. Both species are widely distributed in the Neotropical Region, but the cases of mimicry between them are apparently restricted to populations inhabiting nests of the termite Cornitermes cumulans in the Brazilian Cerrado. Field observations and excavation of the termitaries revealed that Camponotus blandus shares nest chambers and foraging trials with P. termitarius, and workers of both species are mutually tolerant. Our observations suggest that the morphological and behavioral similarities between these species represent a Batesian mimicry relationship in which the relatively palatable Camponotus blandus mimics the unpalatable P. termitarius for predator avoidance. The pacific association between the termitophilous colonies of these species may also suggest some level of parabiotic interaction

The role of Senescent Stem-Galls over Arboreal Ant Communities Structure in Eremanthus erythropappus (DC.) MacLeish (Asteraceae) Trees

The extensive occupation of canopy trees by ants can be attributed to many factors, such as the presence of structures that provide food and shelter. Structures induced by other insects in host plants, like senescent galls, can provide shelter and a nesting place for many species of ants. The main objectives of this work were: (1) to describe the ant communities found in canopies of candeia trees (Eremanthus erythropappus), including the species which use galls as nesting sites; (2) verify the role of galls in determining the structure and composition of the ant communities and (3) to evaluate whether the size and shape of galls are important to the choice of nesting sites by ants. Specifically, the following questions were investigated: 1 – Are larger galls more frequently occupied by ants than smaller galls? 2 – Does gall shape (globular and fusiform) influence occupation? 3 – Which species of ants are present in the canopies of candeias and which are occupying galls? Senescent galls were collected in locations in the southern portion of the Espinhaço Mountain Range, state of Minas Gerais, southeastern Brazil. In total, 3,195 galls were collected and 19 ant species were recorded. Only 176 galls (5.5%) had been occupied by ants, and these were represented by 11 species. The most frequent species found occupying galls were Myrmelachista nodigera, with 48 colonies; Nesomyrmex spininodis, with 37 colonies; and Crematogaster complex crinosa sp. 1, with 29 colonies. The ants occupied galls with greater volume and diameter. Even considering the low occupation frequency, senescent galls in E. erythropappus are used by ants, either as outstations or satellite nests of polydomic colonies, and may be important in determining ant species composition in canopy trees

Ground-Dwelling and Vegetation Ant Fauna in Southern Brazilian Grasslands

Non-forest ecosystems, as natural grasslands from Southern Brazil, are still neglected in conservation policies. Measuring their biodiversity is one of the main steps to generate management strategies for these habitats. This study aims to (i) describe grassland ant richness and composition in Rio Grande do Sul state, and (ii) compare ant communities sampled on the ground and in grassland vegetation, adding to our knowledge of habitat use patterns and vegetation associated species. Six sites were sampled, three belonging to the Pampa biome and three in highland region from the Atlantic Forest biome. Ant fauna was collected once per year in summer during four years in each site with pitfalls traps and sweeping nets. Overall, 29,812 ant individuals were sampled belonging to eight subfamilies, 30 genera e 106 species. The grasslands of Pampa accumulated 91 species and 45 exclusive species, while highland grasslands summed up 61 species and only 15 exclusive species. Species composition differs between biomes as well as between sampling methods. Ant communities sampled from vegetation represented a clear subset of the fauna sampled with pitfall traps, and indication analysis showed only two species associated with this stratum: Myrmelachista gallicola and Pseudomyrmex nr. flavidulus. This study highlights the importance of Southern Brazilian grasslands and the need for specific conservation strategies for the natural grasslands from each biome

Seasonal Patterns of the Foraging Ecology of Myrmelachista arthuri Forel, 1903 (Formicidae: Formicinae)

Temporal dynamics of foraging activity, diet and habitat are key to understanding the bioecology of ants. These patterns are poorly studied in many Neotropical species, such as those belonging to genus Myrmelachista. In the present work, we investigate the foraging behavior and diet of M. arthuri and describe aspects of their food-searching behavior. We recorded the dynamics of workers exiting and entering nests built in the stems of native Atlantic forest trees during the cold/dry and warm/wet seasons. Food items carried by workers were also counted and identified. Myrmelachista arthuri foraged throughout the day, but worker activity became more intense as temperature increased and moisture declined, regardless of the season, and especially in the afternoon. This species had a generalist diet: 92% of the food items were live or dead arthropods or their remains, and a small proportion consisted of plant materials, such as seeds. Arthropod fragments, mostly of M. arthuri workers, represented the largest proportion of the diet, followed by whole Collembola individuals. Food items did not vary between seasons, the number of items was higher in the cold/dry season. The results of this work contribute to the understanding of M. arthuri biology, especially related to foraging dynamics

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.Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNPqFAPEMIGFAPES

Tandem communication improves ant foraging success in a highly competitive tropical habitat

Tropical ants experience intense intra- and interspecific competition for food sources, which influences their activity pattern and foraging strategies. Even though different ant species can coexist through spatial and temporal niche partitioning, direct competition for food cannot be avoided. Recruitment communication is assumed to help colonies to monopolize and exploit food sources successfully, but this has rarely been tested under field conditions. We studied if recruitment communication helps colonies of the Neotropical ant Pachycondyla harpax to be more successful in a highly competitive tropical environment. Additionally, we explored if temporal and spatial niche differentiation helps focal colonies to avoid competition. Pachycondyla harpax competed with dozens of ant species for food. Mass-recruiting competitors were often successful in displacing P. harpax from food baits. However, when foragers of P. harpax were able to recruit nestmates they had a 4-times higher probability to keep access to the food baits. Colonies were unlikely to be displaced during our observations after a few ants arrived at the food source. Competition was more intense after sunset, but a disproportionate increase in activity after sunset allowed focal colonies to exploit food sources more successfully after sunset. Our results support the hypothesis that recruitment communication helps colonies to monopolize food sources by helping them to establish a critical mass of nestmates at large resources. This indicates that even species with a small colony size and a slow recruitment method, such as tandem running, benefit from recruitment communication in a competitive environment