Abstract
The study describes a karyotype of a common parasite of cervids, the giant liver fluke, Fascioloides magna (Trematoda, Platyhelminthes). The chromosome set of F. magna comprises 11 pairs of chromosomes, all classified as subtelocentric except for the submeta-metacentric pair No. 8 and the submetacentric pair No. 10 (2n = 22, n = 1sm + 1sm-m + 9st). The first longest pair is 4.65 μm long and the length decreases continuously to the 1.92 μm length of the last pair No. 11. No distinct secondary constriction has been observed in mitotic preparations. Fluorescent DAPI-staining reveals distinct heterochromatin bands on all 11 chromosome pairs in the centromeric regions; another DAPI-positive bands are localized at the end of the long arms of chromosomes No. 5 and the last less distinct signals appear interstitially on the long arms of the pair No. 6. Synchronous meiotic divisions of 8-spermatocyte groups have been observed during spermatogenesis, similarly with a development of spermatocytes in other trematodes. In the first two stages of heterotypic spermatocyte division, 11 bivalents (n = 11) are regularly observed, confirming the diploid number of 22 elements. Furthermore, the present analysis summarises and discusses available cytogenetic data on Fasciolidae flukes suitable for future studies on taxonomy or phylogenetic interrelationships within the family.