Terrestrial Ants Research Articles

Complexity of cacao production systems affects terrestrial ant assemblages

Given the rapid changes in tropical agricultural production, the evaluation of different management practices has gained interest to determine the effects of land-use change on biodiversity. The conversion of forests into agricultural land is one of the main drivers of diversity loss. Agroforestry systems have been shown as a promising option to provide suitable yields in addition to conserving biodiversity. In this study we compared species richness and community composition of terrestrial ants in six different systems in a long-term experimental site established in 2009 in Bolivia: a full-sun monoculture and an agroforestry system under conventional management, a full-sun monoculture and an agroforestry system under organic management, a highly diverse and dense agroforestry system without external inputs and a secondary forest. Using pitfall traps, we sampled ants four times during a seven-year period (2015-2021). We collected a total of 85 ant species belonging to 6 sub-families and 41 genera. More than 80% of the species were recorded in less than 10% of the traps. Species richness did not significantly differ between the systems. However, species composition mainly differed between the fallow and the production systems, and within the latter, it followed the management intensity gradient, i.e., complex agroforestry, agroforestry and monocultures. The indicator species analysis clearly showed species exclusively associated with one or more production systems, whereas others were only associated with the secondary forest. Species with specialised trophic roles were more frequent in forest and agroforestry systems. Our results showed that the disturbance generated by cultivation was the main driver differentiating ant communities, but also reinforced the importance of the complexity and management intensity of the production system. These results have strong implications for landscape management and highlights the importance of preserving natural patches of forest but also diverse and complex agroforestry systems within the agricultural matrix for ant diversity conservation.

Ants and Restingas: the Relationship Between the Geometric Model, Vegetation Cover, and Myrmecofauna in a Dune Habitat in Bahia, Brazil

In this study, we propose to investigate whether the geometric model and vegetation cover of restinga remnants influences the diversity of ants on the Northern Coast of Bahia. Using Winkler extractors and baits of honey and sardines, the ants were collected from five restinga remnants. Correlations were made between the percentage of soil with vegetation cover, circularity and fractal dimension index and the diversity and richness of ants. Lastly, Kendall correlations and Theil-Kendall regression were performed. The diversity index of ants was not associated with the percentage of soil with vegetation cover. The diversity and richness of terrestrial ants were negatively influenced by the circularity index and positively by the fractal dimension index. The circularity index was inversely proportional, while the fractal dimension index was equivalent to the ant diversity index. The similarity dendrogram showed that areas with less fragmentation had similar myrmecofauna composition. The vegetation cover of the soil does not influence the diversity of ants, but the fragmentation of the areas and the geometric model measured by the fractal dimension index have an influence, being possible that the type of soil, in general, prevents the nesting of a larger volume of species and mask the possibility of finding a closer relationship between these variables.

Trophic specialization on unique resources despite limited niche divergence in a celebrated example of sympatric speciation.

Trophic niche partitioning is observed in many adaptive radiations and is hypothesized to be a central process underlying species divergence. However, patterns of dietary niche partitioning are inconsistent across radiations and there are few studies of niche partitioning in putative examples of sympatric speciation. Here, we conducted the first quantitative study of dietary niche partitioning using stomach contents and stable isotope analyses in one of the most celebrated examples of sympatric speciation: the cichlid radiation from crater lake Barombi Mbo, Cameroon. We found little evidence for trophic niche partitioning among cichlids, including the nine species coexisting in the narrow littoral zone. Stable isotope analyses supported these conclusions of substantial dietary overlap. Our data, however, did reveal that five of eleven species consume rare dietary items, including freshwater sponge, terrestrial ants, and nocturnal foraging on shrimp. Stomach contents of the spongivore (Pungu maclareni) were 20% freshwater sponge, notable considering that only 0.04% of all fishes consume sponges. Overall, we conclude that cichlid species in lake Barombi Mbo overlap considerably in broad dietary niches-in part due to the large proportion of detritus in the stomach contents of all species-but there is evidence for divergence among species in their diet specializations on unique resources. We speculate that these species may utilize these additional specialized resources during periods of low resource abundance in support of Liem's paradox.

Effects of ant colonies on molecular characteristics of dissolved organic matter in peatland soils, Northeast China

Increasing water discharge has resulted in rising dissolved organic matter (DOM) in draining peatlands. However, how contents and spectral characteristics of DOM changed by increasing terrestrial ants in peatland with water level decreasing, were not well revealed. In the present work, chemical and molecular composition of DOM in ant and nearby soils were characterized using UV–Visible absorption and fluorescence excitation-emission matrix (EEM) combined with parallel factor analysis (PARAFAC). Results indicated that four fluorescence components were identified, of which endogenetic fluorophores accounted for a higher proportion (79.21 ± 0.06%) of the total variability of all four. DOM from ant mound soils had lower aromaticity, humification degree, and smaller molecular size than those from control soil. The influence of microorganisms on the content and structure of DOM was crucial in the ant mound soil, whereas the effect from soil physicochemical properties was apparently more pronounced in the control soil. The study demonstrated that the endogenetic and microbial substances were closely related to the compositional variability of DOM in ant and control soils of peatlands.

Arboreal ant abundance tracks primary productivity in an Amazonian whitewater river system

AbstractLittle is known about consumer productivity in the tropics despite the key feedbacks that animals impose on primary productivity. In the Amazon basin, seasonally flooded and unflooded forests exist side by side, and ants (Formicidae) dominate animal biomass. Although flooding has a direct negative effect on soil‐dwelling ants, it is less clear whether flooding has indirect effects on arboreal ants via associated changes in tree communities. To test whether seasonal inundation by whitewater affects arboreal ants, we investigated ant communities in adjacent flooded and unflooded forests along a major whitewater river in central‐western Amazonia. Whitewater‐flooded forest exhibits higher primary productivity than unflooded forest. We thus hypothesized that forest type would affect the productivity and the foraging traits of arboreal ants and that these changes would be mediated by increases in plant‐derived food for ants in flooded forest. We compared ant and plant communities between flooded‐ and unflooded‐forest transects along the Juruá River in Amazonas, Brazil. We collected, identified, and counted terrestrial and arboreal ants, and we measured ant traits with putative relationships to foraging strategy. We also identified plant stems to characterize the abundance of ant food rewards. Flooding negatively affected the diversity and abundance of terrestrial ants but did not change the diversity of arboreal ants. Arboreal ants were more abundant and exhibited higher biomass in flooded forest than in unflooded forest. Arboreal ant traits also suggested that ants may rely more heavily on plant‐derived food in flooded forest than in unflooded forest. These differences were associated with a higher abundance of plant stems predicted to contain ant food rewards in flooded forest than in unflooded forest. Our results indicate that the productivity of arboreal ants is affected by that of the underlying forest. Such effects may be mediated by the predominantly herbivorous foraging strategy of canopy ants, which would link ant populations closely to primary production and stoichiometry. Given ants’ important functional roles, these differences in ant productivity between forest types may have consequences for other arthropods and feedbacks to plants throughout the Amazon basin.

Terrestrial Insects as the Main Food for Freshwater Fish in Sungai Kerian Tributaries: An Implication on Habitat Conservation

The importance of terrestrial insects as food items for freshwater fish was studied by examining stomach contents of Devario regina (Fowler 1934) and its population parameters at canopied areas of selected tributaries of Sungai Kerian, in the northern state of Peninsular Malaysia. Ninety six percent (121 out of 126) of the fish stomachs examined contained food materials in the stomachs and the values of percentage of occurrence (%F), percentage numerical (%N) and percentage points (%P) indicated that collected fish ate similar food items in all rivers. Among the food categories, scavenging terrestrial ants (Formicidae) were the most dominant food item, hence the main diet for this species. The Index of Relative Importance (IRI) scores of food items indicated that ants were higher than other food items. This surface water feeder experienced a positive allometric growth (W = aLb) with a b (rate of growth) value of 3.256. Its asymptotic length, growth constant and growth performance index represented this species with a short life-span (L∞ = 10.90 cm, K = 1.20 year-1, φ’ = 2.15, tmax = 3 year, respectively) and had higher natural mortality (M = 2.40 year-1) than fishing mortality (F = 0.35 year-1) while the fish stock was underexploited (E = 0.13). The finding of this study indicated the importance of terrestrial ants as a food source that support excellent growth of D. regina and the need to conserve riparian trees along river banks to provide allocthonous materials and habitats for the ants.

Amazon Rainforest Ant-Fauna of Parque Estadual do Cristalino: Understory and Ground-Dwelling Ants

Ants are ecologically dominant and have been used as valuable bio-indicators of environmental change or disturbance being used in monitoring inventories. However, the majority of inventories has concentrated in ground-dwelling ant fauna disregarding the arboreal fauna. This paper aimed to list the ant species collected both on the ground and in the vegetation of the Parque Estadual do Cristalino, an important protected site in the center of the southern Amazon. Moreover, we compared the composition of the ground dwelling and vegetation foraging ants. Was sampled 203 species distributed among 23 genera and eight subfamilies, wherein 35 species had not yet been reported in the literature for Mato Grosso State. As expected, the abundance and richness of ants was higher on the ground than in the understory. Also, the ant assemblages composition was different between these habitats (with only 20% occurring in both). It indicate that complementary methods which include arboreal and terrestrial ants are indicated for efficient inventory. This study provides an inventory of the arboreal and ground ant fauna contributing to the knowledge and conservation of ant fauna of the Amazonian.

Registros de Hormigas Y Termitas Presentes en la Dieta de Osos Hormigueros (Mammalia: Myrmecophagidae) en Tres Localidades de Colombia

Anteaters (Mammalia: Myrmecophagidae) feed mainly on ants and termites. Three anteater species are present in Colombia: the giant anteater Myrmecophaga tridactyla, the Northern lesser anteater Tamandua mexicana, and the Southern lesser anteater Tamandua tetradactyla. Nothing is known about their trophic ecology in the country. This study presents records of prey consumed by these species based on the analysis of stomach contents and feces, and compares the interspecific differences in consumed prey types. Data for M. tridactyla were obtained from four fecal samples from the Orinoco region, and the Tamandua samples were obtained from stomach contents of two specimens, one from the Andes region and the second one from the Orinoco region. Twenty-seven ant species were identified, belonging to 14 genera, ten tribes, and five subfamilies. Only two species of termites were found. Tamandua mexicana was the anteater that ate the greatest amount of ant species. Camponotus, Solenopsis and Ectatomma were the most frequent ant genera, and workers were more common than other castes. Tamandua species fed mainly on arboreal ants, while M. tridactyla had only ingested terrestrial ants. The differences between diets of anteaters seem to be related with resource availability and the abundance of ants in the habitat of each species.

Crab regulation of cross-ecosystem resource transfer by marine foraging fire ants

Permeability of boundaries in biological systems is regulated by biotic and/or abiotic factors. Despite this knowledge, the role of biotic factors in regulating resource transfer across ecosystem boundaries has received little study. Additionally, little is known about how cross-ecosystem resource transfer affects source populations. We used experiments, observations and stable isotopes, to evaluate: (1) the proportion of intertidal-foraging black fire ant (Solenopsis richteri) diet derived from marine sources, (2) how black fire ant cross-ecosystem resource transfer is altered by the dominant bioengineer in the intertidal, a burrowing crab (Neohelice granulata), (3) the top-down impact of these terrestrial ants on a marine resource, and (4) the effect of marine resources on recipient black fire ants. We found that more than 85% of the black fire ant diet is derived from marine sources, the number of intertidal foraging ants doubles in the absence of crab burrows, and that ants cause a 50% reduction in intertidal polychaetes. Also, ant mound density is three times greater adjacent to marine systems. This study reveals that cross-ecosystem foraging terrestrial ants can clearly have strong impacts on marine resources. Furthermore, ecosystem engineers that modify and occupy habitat in these ecosystem boundaries can strongly regulate the degree of cross-ecosystem resource transfer and resultant top down impacts.

Habitat and Grazing Influence on Terrestrial Ants in Subtropical Grasslands and Savannas of Argentina

AbstractThe maintenance of species diversity in modified and natural habitats is a central focus of conservation biology. The Iberá Nature Reserve (INR) protects highly diverse ecosystems in northeastern Argentina, including one of the largest freshwater wetlands in South America. Livestock grazing is one of the major disturbances to these ecosystems; however, its effect on ant diversity is poorly known. The objective of this work was to study the effect of savanna versus grassland and grazing on the structure and composition of subtropical terrestrial ants focusing on the particular response of the native red imported fire ant, Solenopsis invicta Buren. Unbaited pitfall traps were used to capture worker ants in 25 grazed and 20 nongrazed sites. Fifty ant species were collected. The savanna showed more species, individuals, biomass, and functional groups of ants than the grassland. S. invicta was the most frequently captured (61.4%) and numerically dominant species; however Camponotus punctulatus punctulatus Mayr showed the highest biomass. Grazing simplified vegetation structure in both habitats, but its impact on vegetation seemed only to promote a higher total biomass especially in the grassland, and/or functional groups, favoring occurrence of hot-climate specialists in the savanna. This study revealed that habitat type strongly affected the organization of the terrestrial ant assemblages at the INR. However, as in other studies, we did not find clear evidence that habitat modification by grazing significantly affected terrestrial ant assemblages. The weak grazing influence could be the consequence of the short enclosure time as to recover the original ant communities, the differential response of ant species to habitat type, and/or the resilience of ants.

Disturbance Type Affects the Distribution of Mobile Invertebrates in a High Salt Marsh Community

Salt marshes are frequently exposed to storm overwashes resulting in large deposits of sand and wrack at the margin of the high marsh and sand dune communities. On Cape Cod, MA, these disturbance-generated areas are dominated by burrows of the crab Uca pugilator and by nest entrances of the ants Formica subsericea and Tetramorium caespitum. We mimicked the effects of storm deposits through additions of sand and wrack and examined their effects on the distributions of the biotic structures of these organisms. We found that while crabs responded negatively to sand deposition, ants did so positively. We suggest that soil temperature and moisture explain these patterns. Wrack deposits extend higher the zone of moist soil and decrease evaporative stress for marine organisms such as crabs, whereas sandy areas tend to be drier and preferred by terrestrial ants. We conclude that disturbance type influences the distribution of these marine and terrestrial organisms over the ecotone.

Environmental Determinants of the Distribution and Abundance of the Ants,Lasiophanes picinusandL. valdiviensis, in Argentina

The distribution and abundance variation of the terrestrial ants, Lasiophanes picinus and Lasiophanes valdiviensis Emery (Formicinae: Lasiini), which are endemic in Patagonia (Argentina and Chile), are described and a set of environmental factors are examined to explain the observed patterns. Ants were collected using 450 pitfall traps arranged in 50, 100 m2 grid plots each with nine traps within a roughly 150 × 150 km area representative of the subantartic-patagonian transition of Argentina. Five sampling periods each 8-days long were carried out between November 2004 and March 2006. To understand the distributional patterns and their link to environmental variables discriminant analysis was used. Path analysis was performed to test for direct and indirect effects of a set of environmental variables on species abundance variation. L. picinus was more frequently captured and attained higher abundance in the forests, while L. valdiviensis was more frequently captured and more abundant in the scrubs. The maximum daily temperature and mean annual precipitation explained L. picinus distribution (i.e. presence or absence) with an accuracy of 90%. L. valdiviensis distribution was predicted with almost 70% accuracy, taking into account herbal richness. The maximum daily temperature was the only climatic variable that affected ant abundance directly; an increase in temperature led to an increase of L. picinus abundance and a decrease of L. valdiviensis abundance. The amount of resources, as indicated by the percent plant cover, explained the variation of the abundance of both species better than the variety of resources as indicated by plant richness (i.e. models including plant richness had low fit or no fit at all). A direct effect of habitat use by cattle was found, as indicated by the amount of feces in the plots, only when variables related to the amount of resources were replaced by variables with less explanatory power related to the variety of resources. This study provides new data on the ecology of Lasiophanes species in relation to existing hypotheses proposed to explain patterns of abundance variation. Evidence is provided that changes in temperature (i.e. global climate change) may have important consequences on populations of these species.

Ecological dominance of the red imported fire ant, Solenopsis invicta, in its native range

Despite the widespread impacts invasive species can have in introduced populations, little is known about competitive mechanisms and dominance hierarchies between invaders and similar taxa in their native range. This study examines interactions between the red imported fire ant, Solenopsis invicta, and other above-ground foraging ants in two habitats in northeastern Argentina. A combination of pitfall traps and baits was used to characterize the ant communities, their dominance relationships, and to evaluate the effect of phorid flies on the interactions. Twenty-eight ant species coexisted with S. invicta in a gallery forest gap, whereas only ten coexisted with S. invicta in a xerophytic forest grassland. S. invicta was the most numerically dominant species in the richest and complex habitat (gallery forest); however it performed better as discoverer and dominator in the simpler habitat. S. invicta was active during day and night. In spite of its poor capacity to discover resources, S. invicta showed the highest ecological dominance and the second-best behavioral dominance after Camponotus blandus. S. invicta won 78% of the interactions with other ants, mostly against its most frequent competitor, Pheidole cf. obscurithorax, dominating baits via mass recruitment and chemical aggression. P. cf. obscurithorax was the best food discoverer. S. invicta won 80% of the scarce interactions with Linepithema humile. Crematogaster quadriformis was one of the fastest foragers and the only ant that won an equal number of contests against S. invicta. The low presence of phorid flies affected the foraging rate of S. invicta, but not the outcome of interspecific interactions. This study revealed that the red imported fire ant ecologically dominated other terrestrial ants in its native range; however, other species were able to be numerically dominant or co-dominant in its presence.

Trophic strategies of garfish, Arrhamphus sclerolepis, in natural coastal wetlands and artificial urban waterways

We used carbon stable isotope and stomach content analyses to test whether snub-nosed garfish, Arrhamphus sclerolepis (Hemiramphidae), in the extensive artificial urban waterways of southeast Queensland, Australia, rely on autotrophic sources different to those in natural wetlands. Carbon isotope values of A. sclerolepis were similar to those in previous investigations, with enriched values in natural habitat (mean = −13.9‰, SE=0.6) and depleted values (−19.1‰, 0.1) in artificial habitat. A. sclerolepis in natural habitat consumed large amounts of seagrass during the day and night, and at night also ingested small quantities of crustacean prey. In artificial habitat, A. sclerolepis consumed macroalgae during the night and switched to invertebrates (terrestrial ants) in the day. Values of δ15 N in all the fish were 3–8‰ more enriched than sources. Mathematical modelling of feasible source mixtures showed that in natural habitat the bulk of the dietary carbon is obtained from seagrass, but the nitrogen is obtained from animal prey. In artificial habitat, carbon is obtained from a mixture of macroalgae and animals. We could not determine the nitrogen sources in artificial habitat of A. sclerolepis since, even after accounting for trophic fractionation of δ15 N, the values were outside the range of potential sources. If the types of animals ingested vary over time, perhaps one or more types of animal important in the provision of nitrogen was not sampled during the study. This study demonstrates that not only does A. sclerolepis occur in both artificial and natural habitats, but it uses the same strategy of bulk herbivory with the inclusion of smaller amounts of animal prey. This understanding of how ecological processes support fisheries production in artificial habitat improves the overall understanding of the effects of urbanisation on coastal food webs.

Methods for conservation outside of formal reserve systems: The case of ants in the seasonally dry tropics of Veracruz, Mexico

Like most ecosystems of the world, tropical dry forests of the central coast of the Gulf of Mexico are inadequately preserved. Given that reserve expansion is unlikely, it is imperative that the conservation capacity of the matrix surrounding reserves is enhanced. Here, we examine the habitat value of isolated pasture trees and patches of secondary regrowth in terms of their terrestrial and arboreal ant assemblages in both a wet and dry season. These simplified wooded systems increase species densities within the agricultural matrix and provide habitat for some forest ant species. Estimated species richness of arboreal ants was particularly low on isolated trees, highlighting an important limitation. This was not the case for terrestrial ants, which were particularly species rich under isolated trees. We also found that the inter-site variations in species densities and similarity to the forest ant assemblage for terrestrial and arboreal strata were not correlated, suggesting that responses to restoration may not be as uniform as often thought. This has important implications for the use of indicator taxa in suggesting the response of other taxa. In terms of species composition, neither secondary regrowth nor isolated trees were appropriate replacements for forest fragments, even though the studied forest fragments were small (13–32ha). The ant assemblages did not exhibit a seasonal change in composition. However, season influenced the contrast between habitats, with isolated trees being more distinct from pasture, and regrowth more closely resembling forests, during the wet season. Microclimatic variables indicate that the forests were least affected by the tropical dry season, and this may contribute to their characteristic fauna. We conclude that even small forest patches make a unique contribution to landscape conservation and that, where reserves are limited, conscientious management of the landscape matrix may provide some species with sufficient new habitat to survive outside of reserve systems. These conclusions are influenced by both season and strata studied.

Seasonal Foraging Activity and Bait Preferences of Ants on Barro Colorado Island, Panama1

ABSTRACTA yearlong arboreal baiting survey of ants was conducted during 1983 on Barro Colorado Island, Panama. Because of a severe El Nino event, the 1983 dry season in Panama was exceptionally long and dry with a distinct boundary between the dry and wet seasons. Baits, located on tree trunks, attracted both terrestrial and arboreal ants, allowing comparisons between the two groups. Species composition at baits changed dramatically with season. Baits were primarily occupied by arboreal species during the dry season, while wet season baits were occupied mostly by terrestrial species. Arboreal and terrestrial ants differed markedly in their preferences for protein‐ or carbohydrate‐based baits; arboreal ants preferred protein‐based baits and terrestrial ants preferred carbohydrate‐based baits. Foraging preference for protein suggests that protein resources were limiting for arboreal ants, particularly during the dry season, and that carbohydrate resources were limiting for terrestrial ants. Fundamental differences in arboreal and terrestrial habitats may promote the differences in foraging strategies observed during an annual cycle in a seasonal tropical forest.

Field host range of the fire ant pathogens Thelohania solenopsae (Microsporida: Thelohaniidae) and Vairimorpha invictae (Microsporida: Burenellidae) in South America

We studied the field host specificity of the microsporidia Thelohania solenopsae and Vairimorpha invictae and their prevalence in the imported fire ants, Solenopsis invicta and S. richteri. Terrestrial ants were sampled by using bait traps and/or nest sampling at preselected sites in Argentina and Brazil. The sampling included the genera Solenopsis, Pheidole, Camponotus, Crematogaster, Linepithema, Brachymyrmex, Paratrechina, Dorymyrmex, and Wasmannia. The samples were examined under a phase-contrast microscope for the presence of microsporidian infections. The bait trap sampling revealed that: (1) T. solenopsae infected only S. richteri, S. invicta, and Solenopsis sp. at 6–67% of the sites and in 1.5–29% of the traps; (2) V. invictae infected only S. invicta at 6% of the sites and in 3% of the samples. The nest sampling revealed that: (1) T. solenopsae infected S. invicta, S. richteri, and S. macdonaghi, at 41–67% of the sites and in 11–58% of the colonies; (2) V. invictae infected the same species at 15–50% of the sites and in 2–26% of the colonies. We detected T. solenopsae and V. invictae in equal percentages of S. invicta sites (41%); however, the percentage of colonies infected with V. invictae was 20% and with T. solenopsae only 11%. At S. richteri sites, in contrast, T. solenopsae occurred at 46% of the sites and 15% of the colonies and V. invictae occurred at only 15% of the sites and 2% of the colonies. In S. macdonaghi, T. solenopsae was detected at 67% of the sites and 58% of the colonies, and V. invictae was detected at 50% of the sites and 26% of the colonies. This is the first report of V. invictae infecting S. macdonaghi. The proportion of S. richteri and S. invicta infected with T. solenopsae was similar. In contrast, the proportion of S. invicta infected with V. invictae was higher than S. richteri. We conclude that the microsporidia, T. solenopsae and V. invictae, show a very high specificity for Solenopsis ants in the field. It appears that T. solenopsae infects S. invicta and S. richteri equally but V. invictae may be more adapted to infect S. invicta. Published by Elsevier Science (USA).

Seasonal Foraging Activity and Bait Preferences of Ants on Barro Colorado Island, Panama1

A yearlong arboreal baiting survey of ants was conducted during 1983 on Barro Colorado Island, Panama. Because of a severe El Niño event, the 1983 dry season in Panama was exceptionally long and dry with a distinct boundary between the dry and wet seasons. Baits, located on tree trunks, attracted both terrestrial and arboreal ants, allowing comparisons between the two groups. Species composition at baits changed dramatically with season. Baits were primarily occupied by arboreal species during the dry season, while wet season baits were occupied mostly by terrestrial species. Arboreal and terrestrial ants differed markedly in their preferences for protein- or carbohydrate-based baits; arboreal ants preferred protein-based baits and terrestrial ants preferred carbohydrate-based baits. Foraging preference for protein suggests that protein resources were limiting for arboreal ants, particularly during the dry season, and that carbohydrate resources were limiting for terrestrial ants. Fundamental differences in arboreal and terrestrial habitats may promote the differences in foraging strategies observed during an annual cycle in a seasonal tropical forest.

Ant Diversity and Abundance along an Elevational Gradient in the Philippines1

ABSTRACTAnt communities were surveyed along an elevational gradient in the Philippines extending from lowland dipterocarp forest (250 m elevation) to mossy forest (1750 m). Standardized pitfall trapping in arboreal and terrestrial microhabitats at seven sites yielded 51 species. Collecting by hand at five of the sites yielded 48 species. The two methods produced substantially different assemblages, with only 22 species (29%) taken in common. Only a fraction of the total ant community appeared to be sampled at most of the sites. Measures of species richness and relative abundance peaked at mid‐elevations and declined sharply with increasing elevation. Ants were extremely rare above 1500 m elevation. Arboreal ants were trapped much less frequently than terrestrial ants at all sites. Ant species that were abundant had broader elevational distributions than those that were less common, but most species were rare and occurred at only one or two sites. The elevational patterns for ants are largely the inverse of those documented for Philippine small mammals which reach their greatest diversity and abundance at high elevations where ants are rare. This suggests that the two groups may interact competitively. Some of the patterns observed or inferred from this study may apply to tropical ant communities in general, and are presented as series of testable hypotheses as a guide and stimulus for future research.

Description of a new ecuadorean gnamptogenys species (hymenoptera: formicidae), with a discussion on the status of the alfaria group

Description of a new ecuadorean gnamptogenys species (hymenoptera: formicidae), with a discussion on the status of the alfaria group