Comparative karyological analysis of three species of Bothriocephalus Rudolphi 1808 (Cestoda: Pseudophyllidea)

The diploid complements of mitotic metaphase plates of three species of Botriocephaluswere studied using conventional Giemsa staining and karyometric analysis. Botriocephalus claviceps and Botriocephalus gregarius showed a karyotype with 2n=14 chromosomes. All chromosomes of B. claviceps were biarmed, metacentric or meta-submetacentric. The two first pairs of homologues were markedly larger than the remaining elements and represented 48.62% of the total chromosome length. The karyotype of B. gregarius had similar metric values for the chromosomes, but clearly differed in the chromosome morphology of pairs 5, 6 and 7, which had terminally located centromeres. The diploid number 2n=12 was found in Botriocephalus scorpii. The karyotype consists of five pairs of metacentric and one pair of submeta-metacentric chromosomes. The possible pathways of karyotype evolution within Bothriocephalus spp. and their phylogenetic relations with the other karyologically studied groups in the order Pseudophyllidea are discussed.