Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning.

The soil fauna of the tropics remains one of the least known components of the biosphere. Long-term monitoring of this fauna is hampered by the lack of taxonomic expertise and funding. These obstacles may potentially be lifted with DNA metabarcoding. To validate this approach, we studied the ants, springtails and termites of 100 paired soil samples from Barro Colorado Island, Panama. The fauna was extracted with Berlese-Tullgren funnels and then either sorted with traditional taxonomy and known, individual DNA barcodes (“traditional samples”) or processed with metabarcoding (“metabarcoding samples”). We detected 49 ant, 37 springtail and 34 termite species with 3.46 million reads of the COI gene, at a mean sequence length of 233 bp. Traditional identification yielded 80, 111 and 15 species of ants, springtails and termites, respectively; 98%, 37% and 100% of these species had a Barcode Index Number (BIN) allowing for direct comparison with metabarcoding. Ants were best surveyed through traditional methods, termites were better detected by metabarcoding, and springtails were equally well detected by both techniques. Species richness was underestimated, and faunal composition was different in metabarcoding samples, mostly because 37% of ant species were not detected. The prevalence of species in metabarcoding samples increased with their abundance in traditional samples, and seasonal shifts in species prevalence and faunal composition were similar between traditional and metabarcoding samples. Probable false positive and negative species records were reasonably low (13–18% of common species). We conclude that metabarcoding of samples extracted with Berlese-Tullgren funnels appear suitable for the long-term monitoring of termites and springtails in tropical rainforests. For ants, metabarcoding schemes should be complemented by additional samples of alates from Malaise or light traps.

Six new taxa of Campodeidae (Diplura) are described in the genera Litocampa, Juxtlacampa, Oncinocampa, and Tachycampa. We also redescribe the interesting species Juxtlacampa juxtlahucensis Wygodzinsky, 1944 from Juxtlahuaca cave in Guerrero, Mexico. All of these taxa are cave-dwelling species with more or less noticeable troglobiomorphic features They inhabit the subterranean ecosystem in six limestone massifs and one lava tube cave in the central states of Mexico. Four of these species are included in the “tachycampoide” group and one species in the “podocampoide” group (sensu Bareth & Conde). Nine species already known in Central and South America of the “tachycampoide” group, in such poorly-sampled regions compared with the eight species in the well-sampled Mediterranean region (Ibero-Sardinia and north Africa), suggest an American origin for this group.

A new diagnosis of Denisiella is provided, based on the revision of most descriptions, including three new species from Brazil. New Brazilian taxa share the presence of 6 + 6 eyes, 4 + 4 serrate spine-like on tibiotarsi III and the polycarinate setae on tibiotarsi II but differ from each other by the shape and size of the sensilla of the tibiotarsi I. Denisiella rhizophorae sp. nov. has the combination of sensilla on tibiotarsi I of rhagidial type and C2 blunt on antennal segment III. Only D. betschi sp. nov. has barbulate spines on head and D. caatingae sp. nov. is the only which males present nasal organ. They are illustrated with drawings and scanning electron microscope photographs. Three different shapes of sensilla in the tibiotarsi I were observed and were compared with other species.

Robust data to refute or support claims of global insect decline are currently lacking, particularly for the soil fauna in the tropics. DNA metabarcoding represents a powerful approach for rigorous spatial and temporal monitoring of the taxonomically challenging soil fauna. Here, we provide a detailed field protocol, which was successfully applied in Barro Colorado Island (BCI) in Panama, to collect soil samples and arthropods in a tropical rainforest, to be later processed with metabarcoding. We also estimate the proportion of soil/litter ant, springtail and termite species from the local fauna that can be detected by metabarcoding samples obtained either from Berlese-Tullgren (soil samples), Malaise or light traps. Each collecting method detected a rather distinct fauna. Soil and Malaise trap samples detected 213 species (73%) of all target species. Malaise trap samples detected many ant species, whereas soil samples were more efficient at detecting springtail and termite species. With respect to long-term monitoring of soil-dwelling and common species (more amenable to statistical trends), the best combination of two methods were soil and light trap samples, detecting 94% of the total of common species. A protocol including 100 soil, 40 Malaise and 80 light trap samples annually processed by metabarcoding would allow the long-term monitoring of at least 11%, 18% and 16% of species of soil/litter ants, springtails and termites, respectively, present on BCI, and a high proportion of the total abundance (up to 80% of all individuals) represented by these taxa.