Background Polyploidy, although still poorly explored, represents an important evolutionary event in several cyprinid clades. Herein, Catlocarpio siamensis and Probarbus jullieni - representatives of the paleotetraploid tribe Probarbini, were characterized both by conventional and molecular cytogenetic methods. Results Alike most other paleotetraploid cyprinids (with 2n = 100), both species studied here shared ...