Range Expansion of the Vulnerable Piabanha Brycon dulcis (Bryconidae) to the Upper Doce River Basin, Brazil

The Doce River basin, in the Atlantic Forest of Brazil, is home to a rich diversity of fish species, many of which are endemic and endangered. This area has become a priority for conservation efforts, particularly in the wake of the environmental disaster resulting from the collapse of the Fundão Dam in Mariana in 2015. Among the endemic species is Brycon dulcis Lima et Vieira, 2017, a rare species currently listed as Vulnerable according to the last evaluation by the Brazilian Ministry of the Environment, which, until now, was thought to be restricted to the middle and lower reaches of the basin. This study expands the known geographic distribution of B. dulcis to the upper Doce River through the morphological analysis of 14 lots of Brycon Müller et Troschel, 1844 deposited in the Ichthyological Collection of the Museu de Zoologia João Moojen. The identification of B. dulcis was based on diagnostic characters as proposed in the original description, thus confirming its presence in the upper course of the Doce River and in tributaries such as the Piranga River. This broader range suggests the existence of individuals in less-impacted areas, serving as ecological refuges and genetic reservoirs for the species’ recovery. However, threats like mining, hydroelectric dams, and invasive species persist. The findings underscore the value of scientific collections for biodiversity research and stress the need for urgent conservation, including habitat protection and a reassessment of the species’ threatened status.