Abstract Chironius laurenti was described based on 27 specimens from localities of the Beni savanna and Chiquitano Dry Forest in Bolivia and one specimen from the Brazilian Cerrado. We examined the holotype of C. laurenti from the department of Beni, Bolivia, as well as most of the paratypes and expanded sample obtained in zoological collections. Based on morphological and molecular data, we restrict the name C. laurenti to the populations distributed throughout the Madeira River Basin and conclude that the known records throughout the Pantanal wetlands and transition areas with the Cerrado savanna represent a distinct entity erroneously attributed to this name. Therefore, we describe the latter populations as a new species endemic to the Upper Paraguay River Basin, distinguished from its congeners by a unique combination of qualitative and quantitative morphological characters (meristic, color pattern, and cranial osteology) and unequivocal molecular evidence. We report on relevant behavioral observations of the new species, specifically its foraging strategy on riverbanks and male-male combat, which may occur during the mating season. Additionally, we discuss possible diversification hypotheses in the Upper Paraguay River Basin and highlight the importance of conserving ecological corridors linking the Pantanal to the surrounding plateaus, as ongoing climate changes may restrict or displace present species’ distributions. http://www.zoobank.org/urn:lsid:zoobank.org:pub:D1DCEB24-8C69-4B76-8387-CD9ACB23C733 .
Sudré et al. (2026) studied this question.