Key to species of Romanogobio in the Danube River drainage

1a Epithelial crests on the predorsal back absent................................................................ 2

1b Epithelial crests on the predorsal back present............................................................... 3

2a Barbel reaching to posterior eye margin or just shortly beyond; 8½ branched dorsal-fin rays; midlateral dark-grey blotches iso- lated from the dark-grey saddles on the back; breast usually naked..................................... R. skywalkeri

2b Barbel reaching always beyond posterior eye margin, often to operculum; 7½ branched dorsal-fin rays; midlateral dark-grey blotches usually fused to dark-grey saddles behind the dorsal-fin base; breast covered by scales............ R. uranoscopus

3a Usually 7½ branched dorsal-fin rays; caudal peduncle strongly compressed; pectoral fin reaching to middle between pectoral- and pelvic-fin origins......................................................................... R. vladykovi

3b Usually 8½ branched dorsal-fin rays; caudal peduncle slightly compressed, pectoral fin reaching to or almost to pelvic-fin ori- gin.................................................................................................. 4

4a 4 scales between lateral line and pelvic fin origin; eye diameter 17–23 % HL............................... R. antipai

4b 3 scales between lateral line and pelvic-fin origin; eye diameter 20–28 % HL............ R. kesslerii & R. carpathorossicus