An unusually complex venom system in araneophagous palp-footed spiders (Palpimanidae)

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  An unusually complex venom system in araneophagous palp-footed spiders (Palpimanidae) Venoms are key adaptive traits in many animal lineages, yet their structural and functional diversity in spiders remains poorly investigated. Here, we present an initial characterization of the venom system of palp-footed spiders (Palpimanidae), a family specialized in hunting other spiders. Using micro-computed tomography, we found that the venom glands of the single species examined, Palpimanus gibbulus , exhibit a complex, multi-lobed morphology that is unusual among araneomorph spiders. Proteo-transcriptomic analyses of two Palpimanus venoms ( P. gibbulus and P. cyprius ) revealed highly diverse putative toxin repertoires comprising hundreds of peptides and proteins, including numerous novel putative neurotoxins, cytotoxins, enzymes, and allergens. Five major families of cysteine-rich palpitoxins were identified as the dominant putative neurotoxic components in both species, displaying con...

Most soil and litter arthropods are unidentifiable based on current DNA barcode reference libraries

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Most soil and litter arthropods are unidentifiable based on current DNA barcode reference libraries

Abstract

We are far from knowing all species living on the planet. Understanding biodiversity is demanding and requires time and expertise. Most groups are understudied given problems of identifying and delimiting species. DNA barcoding emerged to overcome some of the difficulties in identifying species. Its limitations derive from incomplete taxonomic knowledge and the lack of comprehensive DNA barcode libraries for so many taxonomic groups. Here, we evaluate how useful barcoding is for identifying arthropods from highly diverse leaf litter communities in the southern Appalachian Mountains (USA). We used 3 reference databases and several automated classification methods on a data set including several arthropod groups. Acari, Araneae, Collembola, Coleoptera, Diptera, and Hymenoptera were well represented, showing different performances across methods and databases. Spiders performed the best, with correct identification rates to species and genus levels of ~50% across databases. Springtails performed poorly, no barcodes were identified to species or genus. Other groups showed poor to mediocre performance, from around 3% (mites) to 20% (beetles) correctly identified barcodes to species, but also with some false identifications. In general, BOLD-based identification offered the best identification results but, in all cases except spiders, performance is poor, with less than a fifth of specimens correctly identified to genus or species. Our results indicate that the soil arthropod fauna is still insufficiently documented, with many species unrepresented in DNA barcode libraries. More effort toward integrative taxonomic characterization is needed to complete our reference libraries before we can rely on DNA barcoding as a universally applicable identification method.


Recuero, E., Etzler, F. E., & Caterino, M. S. (2024). Most soil and litter arthropods are unidentifiable based on current DNA barcode reference libraries. Current Zoology, 70(5), 637-646. https://doi.org/10.1093/cz/zoad051