GENETIC-EVIDENCE TO CLARITY THE SYSTEMATIC STATUS OF THE GENERA ZACCOAND CANDIDIA (CYPRINIFORMES, CYPRINIDAE)

Genetic relationships among species of the genera Zacco and Candidia w ere analyzed using allozyme data from sampled specimens collected from 6 rivers in Taiwan. A total of 78 alleles were resolved for 26 loci f rom 13 enzyme systems. Nei's genetic distance between 2 congeneric spe cies (Zacco pachycephalus and Z. platypus) was 0.285, which is within the range for the same genus. A slightly larger mouth cleft, smaller l ateral line scales, and fixed alleles at mMDH100, ME-1*100, PGI-B*100 , PGM1100, and PGM-2*100 in Zacco pachycephalus can be used to distin guish it from Z. platypus. Comparison with Aphyocypris kikuchii, Candi dia barbatus showed more distant relationships with these 2 Zacco spec ies, suggesting that Zacco and Candidia are 2 distinct genera. In addi tion, a barbel at mouth corner, and fixed alleles at sAAT-1120, CK-A* 93, FH-180, FH-2*82, G(6)PDH-1*80, IDHP-1*113, IDHP-3*120, ME-1*103, ME-250, PGM-1*120, and PGM-2*120 in Candidia can also be used to dist inguish it from the genus Zacco. The colonization and speciation event of the genus Zacco in Taiwan was discussed in detail.