Onychostoma krongnoensis sp. nov. is differentiated
from Onychostoma dongnaiensis sp. nov. by body depth (4.0 vs. 3.2 times in SL), predorsal scale number (14−17 vs.
14−15), dorsal-fin length (4.5 vs. 4.2 times in SL), caudal-peduncle length (3.9 vs. 4.2 times in SL), colour in life (dark
vs. bright), and by mitochondrial DNA (0.2% sequence divergence). Molecular evidence indicates that both species are
members of Onychostoma and are distinct from all congeners sampled (uncorrected sequence divergences at the 16S
rRNA gene of >2.0% for all Onychostoma for which homologous 16S rRNA sequences are available).