Metzia

This species can be distinguished from congeners by the following combination of characters: 18–20 (vs. 10-18) branched anal-fin rays; 49–55 (vs. 35-48) lateral-line scale rows; 33–36 (vs. 15-20) predorsal sca...

Although it is included in the genus Metzia this grouping remains somewhat unresolved in terms of taxonomy and it may contain more than a single genetic lineage. For example, members share a number of characters with the genera Ischikauia Jordan and Snyder 1900, Hemiculterella Warpachowski 1887, and several species of Anabarilius Cockerell 1923, including a bipartite gas bladder, a non-spinous dorsal-fin ray, and a sharp ventral keel between the pelvic-fin insertion and anus.

Populations from the upper Pearl River (Nanpan Jiang basin) differ in several morphological characters from those inhabiting Guangdong, Guangxi, and Guizhou Provinces, and Hainan Island. Those from Vietnam also seem to be different (Gan et al., 2009), the implication being that there may be several species currently included under the name M. lineata.