Abstract: We provide here a checklist of the ants of French Guiana, an overseas department of France situated in northern South America, with a very low human population density and predominantly covered by old-growth tropical rainforests. Based on 165 scientific papers, specimens deposited in collections, and unpublished surveys, a total of 659 valid species and subspecies from 84 genera and 12 subfamilies is presented. Although far from complete, these numbers represent approximately 10% of the ant diversity known to occur in the Neotropical realm. Additionally, three ant genera and 119 species are reported for the first time for French Guiana. Finally, five species are recognized as erroneous records for the the department in the literature. This checklist significantly expands the basic knowledge of the ants in the Guiana Shield, one of the world’s most important biodiversity hotspots.

Abstract: Ants constitute a substantial part of the arthropod biomass in rainforests. Most studies have focused on ground-dwelling ants, which constitute almost half of the diversity of the ant assemblage. We report here the results of the first survey of tree-dwelling ants in French Guiana on a plateau and in a swamp palm forest (Euterpe oleracea Mart.) in the Mitaraka Mountains. We were interested in seeing the effect of topography and geographic distance on species richness and composition and to gather information on the species distribution on tree trunks. The fauna of Mitaraka was compared with one from a site 350 km distant (Petit Saut). In total 105 trees were sampled (30, 30, 45 in the plateau and the swamp forests of Mitaraka, and in Petit Saut plateau forest, respectively). Arboreal ants were attracted using tuna and honey baits spread along a rope reaching an upper branch, except for the palm swamp forest where the baits were only placed at 2 m high. A total of 34, 13 and 22 species were observed in these three respective sites. Six of these species are new records for French Guiana. In Mitaraka Camponotus femoratus (Fabricius, 1804) and Crematogaster leviorLongino, 2003 co-occurred on trees (parabiotic association) and were among the most common species, along with Crematogaster tenuiculaForel, 1904 which was found on other trees (species exclusion). The Mitaraka Mountains appeared more species rich and had a species composition distinct from Petit Saut. Topography also influenced ant species composition. Almost half of the species collected by the baitline method were exclusively foraging in the canopy.

Abstract: Epiphytes represent up to 50% of all plant species in rainforests, where they host a substantial amount of invertebrate biomass. Efficient surrogates for epiphyte invertebrate communities could reduce the cost of biomonitoring surveys while preventing destructive sampling of the plants. Here, we focus on the invertebrate communities associated to tank bromeliads. We ask whether the presence of particular ant and/or spider taxa (easily surveyed taxa) that use these plants as nesting and/or foraging habitats predicts functional trait combinations of aquatic invertebrate communities hosted by the plants. Functional community composition of invertebrates was predicted both by bromeliad habitat features and the presence of certain ant and spider species. The ant Azteca serica preferred wider bromeliad rosettes that trap large amount of detritus, indicating interstitial-like food webs dominated by deposit feeders that burrow in fine particulate organic matter. Leucauge sp. spiders preferred narrower bromeliad rosettes bearing smaller detrital loads, thereby indicating a dominance of pelagic filter-feeding and predatory invertebrates in the water-filled leaf axils. Both Neoponera villosa ants and Eriophora sp. spiders preferred rosettes at intermediate size bearing moderate amounts of detritus, indicating a benthic food web dominated by leaf shredders and gathering collectors. Owing to the animal diversity and biomass supported by rainforest epiphytes, our approach would deserve to be further tested on a range of epiphytes involved in tight interactions with invertebrates. In this context, surrogate species could serve both as indicators of functional diversity, and as early-warning indicators of network disassembly.