L. siamensis can be distinguished from congeners by the following combination of characters: 39-42 scales in the lateral series; shoulder spot usually absent, but sometimes well-defined; body with longitudinal stripes formed by a spot on each scale; dorsal fin with dusky median stripe and no red coloration; caudal fin dusky, sometimes with reddish coloration, but no well-defined stripes; 20-23 circumpeduncular scales…

Different populations vary in appearance somewhat (see image of Salween specimen for example), and L. leptocheilus may turn out to represent a group of closely-related species rather than a single taxon. The population from the Cambodian Mekong has been considered to represent a distinct species, Labiobarbus lineatus, although that name is currently a synonym of L. leptocheilus following Kottelat (2013). It is widely used in the ornamental trade, however.

The vernacular name ‘lancer’ is derived from the extended dorsal spine possessed by several members of the genus, which currently contains 7 species. B. obscurus is diagnosable from congerners by the following combination of characters: mouth opening relatively small and narrow; oral dentition significantly reduced; dorsal-fin spi…