Allozyme discrimination of three species of Loricariichthys (Siluriformes: Loricariidae) from southern Brazil

Abstract

Three species of armored catfish of the genus Loricariichthys were clearly discriminated by starch gel isozyme electrophoresis on heart, liver and muscle tissues. We scored 21 enzyme loci from 14 isozyme systems (ACP, ADH, AAT, EST, GCDH, G3PDH, G6PDH, GPI, ICDH, LDH, MDH, MDHP, PGM and SOD). Expected mean heterozygosity (He) ranged from 0.023 in Loricariichthys anus to 0.050 in L. platymetopon and 0.035 in Loricariichthys sp. The percentage of polymorphic loci (P0.99) was 14.3% for the three analyzed species. Nei's genetic identity (I) was found to be 0.663 between Loricariichthys anus and Loricariichthys sp., 0.329 between L. anus and L. platymetopon, and 0.478 between L. platymetopon and Loricariichthys sp. Genetic variability, tissue specific differences, as well as applicability of isozyme electrophoresis as a tool for neotropical fish systematists are discussed.