MORPHOMETRIC AND ALLOZYME VARIATION IN THE AFRICAN CATFISHES CLARIAS-GARIEPINUS AND C-ANGUILLARIS

This study investigated morphological characters and electrophoretic p olymorphism at 25 protein loci in nine wild populations of the African clariid catfish Clarias gariepinus and seven wild populations of C. a nguillaris. Two other clariid species, Clarias albopunctatus and Heter obranchus longifilis, were used as outgroups in the allozyme study. Mo rphometric and allozyme data are congruent for the Nilo-Sudanian popul ations of C. gariepinus and C. anguillaris. Both approaches also disti nguished two groups amongst the C, gariepinus populations, one contain ing Nilo-Sudanian populations and the other including Lake Victoria an d southern African populations. However, allozyme data suggest that C. gariepinus is not a monophyletic group and show that C. albopunctatus is more divergent from C. gariepinus and C. anguillaris than it is fr om H. longifilis, stressing the need for a revision of clariid systema tics. The variation observed in C. gariepinus is discussed in terms of palaeogeographical events and its use in aquaculture. (C) 1998 The Fi sheries Society of the British Isles.