Zoological Studies

Genetic Evidence to Clarify the Systematic Status of the Genera Zacco and Candidia (Cypriniformes: Cyprinidae)

Hurng-Yi Wang, Sin-Che Lee and Ming-Jenn Yu (1997) Genetic evidence to clarify the systematic status of the genera Zacco and Candidia (Cypriniformes: Cyprinidae). Zoological Studies 36(3): 170-177. Genetic relationships among species of the genera Zacco and Candidia were analyzed using allozyme data from sampled specimens collected from 6 rivers in Taiwan. A total of 78 alleles were resolved for 26 loci from 13 enzyme systems. Nei's genetic distance between 2 congeneric species (Zacco pachycephalus and Z. platypus) was 0.285, which is within the range for the same genus. A slightly larger mouth cleft, smaller lateral line scales, and fixed alleles at mMDH*100, ME-1*100, PGl-8*100, PGM-1*100, and PGM-2*100 in Zacco pachycephalus can be used to distinguish it from Z. platypus. Comparison with Aphyocypris kikuchii, Candidia barbatus showed more distant relationships with these 2 Zacco species, suggesting that Zacco and Candidia are 2 distinct genera. In addition, a barbel at mouth corner, and fixed alleles at sAAT-1*120, CK-A*93, FH-1*80, FH-2*82, G6PDH-1*80, IDHP-1*113, IDHP-3*120, ME-1*103, ME-2*50, PGM-1*120, and PGM-2*120 in Candidia can also be used to distinguish it from the genus Zacco. The colonization and speciation event of the genus Zacco in Taiwan was discussed in detail.