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 mites 1 . Extant chelicerates share a unique anatomical character, the chelicerae—feeding first appendages terminated by a simple pincer-like chela 2 . The fossil record of these primarily predatory animals spans almost 500 million years 3 , suggesting a likely yet undocumented origin during the Cambrian Explosion. Artiopods 4 , 5 , 6 , megacheirans 4 , 7 , 8 , 9 , habeliids 10 , 11 , 12 , 13  and mollisoniids 14 , 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 Ut...

Taxonomic redescription of Tityus (Tityus) proseni Abalos 1954 (Scorpiones: Buthidae) and first record for the departments of Beni and Santa Cruz - Bolivia

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Taxonomic redescription of Tityus (Tityus) proseni Abalos 1954 (Scorpiones: Buthidae) and first record for the departments of Beni and Santa Cruz - Bolivia

Abstract

In 1954 Abalos described the species Tityus proseni with specimens found in Cochabamba-Bolivia, however, since then the data of the species have not been updated. New specimens were recently captured from the departments of Beni and Santa Cruz - Bolivia. In order to carry out a detailed redescription and expansion of the distribution data of the species in Bolivia, these were reviewed according to: its external morphology, pigmentation patterns and morphometric data. The data resulting from the analysis provide new characters for the species, not contemplated in the original description, new ranges in morphometric variables previously analyzed, new data on pigmentation patterns. On the other hand, the differential morphological and morphometric data of T. proseni with those of T. argentinus and T. sorataensis are presented, since they are apparently similar species within the country.

Humboldt-Paputsachis, Ciro, Villarreal-Carvajal, Jeysa Camila, & Fortún Fernández, Evelin Esther. (2025). Taxonomic redescription of Tityus (Tityus) proseni Abalos 1954 (Scorpiones: Buthidae) and first record for the departments of Beni and Santa Cruz - Bolivia. Journal of the Selva Andina Research Society , 16 (2), 81-91. Epub 2025 Aug 31. https://doi.org/10.36610/j.jsars.20252326