not a species from Argentina:
Characidium zebra Eigenmann, 1909
published in:
Terán, G.E., V.E. Méttola, F. Alonso, M.M. Montes, A. Méndez-López, G. Miranda, G. Aguilera & J.M. Mirande (2026):
A new species of Characidium (Characiformes: Crenuchidae) from the Northwestern La Plata basin in Argentina.
Ichthyology & Herpetology 114 (2): 283-298
abstract (from publication):
Using an integrative approach that combines molecular and morphological analyses, we describe Characidium lilloi, a new species from the Andean portion of the northwestern La Plata basin, specifically from the upper Bermejo and Juramento River basins in Argentina. Specimens were examined for morphometric, meristic, and osteological traits. Genetic analyses based on COI and CYTB sequences were conducted to infer its phylogenetic relationships. The new species is distinguished by a unique combination of morphological characters including an unscaled isthmus, absence of dark stripes or spots on fins, 7–13 regular transversal bars, 14 scales around the caudal peduncle, 35–37 scales in longitudinal series, and highly developed nasal flaps; and molecular evidence. Characidium lilloi, new species, was found to be closely related to C. fasciatum and C. gomesi and represents the first known member of the C2-Clade in the northwestern La Plata basin. Ecologically, C. lilloi, new species, inhabits fast-flowing mountain rivers within the Yungas and Chacoan. This discovery underscores the northwestern La Plata basin as a biogeographic hotspot of endemism and reinforces its importance as a high-priority area for freshwater conservation.