NEW EVIDENCE OF HEXAPLOIDY IN LARGE AFRICAN BARBUS WITH SOME CONSIDERATIONS ON THE ORIGIN OF HEXAPLOIDY

Three species of 'large' African Barbus from the Republic of Guinea (W est Africa), were characterized by the chromosome numbers (2N) of 148 (B. bynni occidentalis and B. wurizi) and 150 (B. petitjeani Daget, 19 62). All these species have st karyotype which corresponds to the evol utionary hexaploid level. The karyotype of B. petitjeani is composed o f chromosomes clearly grouped into morphologically homomorphic sextets which may document the origin of hexaploidy via an autopolyploidic ev ent. Present findings extend the known distribution of evolutionary he xaploidy in 'large' African Barbus to West Africa and show evidence of the pan-African distribution of this phenomenon. (C) 1995 The Fisheri es Society or the British Isles