New and interesting spiders (Arthropoda, Araneae) from Vashlovani National Park and Chachuna Managed Reserve (Georgia). Part II

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  New and interesting spiders (Arthropoda, Araneae) from Vashlovani National Park and Chachuna Managed Reserve (Georgia). Part II Spiders collected individually during short outings at different locations, as well as during a trip to Vashlovani National Park and Chachuna Managed Reserve, were identified, resulting in the recognition of 22 species, of which three are described as new: Harpactea digitata Seropian, sp. nov. (♂, Dedoplistskaro) (Dysderidae), Leptopilos longiembolus Seropian & Japaridze, sp. nov. (♂, Vashlovani National Park), and Palpimanus obscurus Seropian & Bulbulashvili, sp. nov. (♂♀, Georgia, Azerbaijan, and Iran) (Palpimanidae). A female of Synema inexpectatum Seropian, Bulbulashvili, Makharadze & Baznikin, 2024, collected with several males, is described, while the species is recorded for the first time from the Kvemo Kartli region. Furthermore, Bogdocosa kronebergi (Andreeva, 1976), Marinarozelotes adriaticus (Caporiacco, 1951), and Pseudicius palae...

A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates

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A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates

Abstract

Chelicerata is a megadiverse (over 120,000 species) arthropod clade that includes familiar taxa of profound ecological and economic importance, such as scorpions, spiders and mites1. Extant chelicerates share a unique anatomical character, the chelicerae—feeding first appendages terminated by a simple pincer-like chela2. The fossil record of these primarily predatory animals spans almost 500 million years3, suggesting a likely yet undocumented origin during the Cambrian Explosion. Artiopods4,5,6, megacheirans4,7,8,9, habeliids10,11,12,13 and mollisoniids14,15 have been considered Cambrian stem- or crown-group chelicerates, but they all lack unequivocal chelicerae, leaving the emergence of chelicerae-bearing arthropods unclear. Here we describe Megachelicerax cousteaui gen. et sp. nov., a large soft-bodied arthropod from the middle Cambrian of Utah featuring massive three-segmented chelicerae, along with five pairs of pseudobiramous prosomal limbs with non-foliaceous exopodal rami, and plate-like lamellae-bearing opisthosomal appendages. Bayesian and parsimony phylogenetic analyses resolve Megachelicerax as a stem-group chelicerate bridging Cambrian habeliids and post-Cambrian chelicerae-bearing synziphosurines. This finding provides unequivocal evidence of large predatory chelicerates in the Cambrian, illuminates their body plan’s origin, and confirms habeliids, mollisoniids and probably megacheirans as members of total-group Chelicerata.

Lerosey-Aubril, R., & Ortega-Hernández, J. (2026). A chelicera-bearing arthropod reveals the Cambrian origin of chelicerates. Nature, 1-7. https://doi.org/10.1038/s41586-026-10284-2