Karyological studies of bovine pancreatic flukes (Eurytrema sp.) and their phenotypes.

Chromosomes of gonadal tissues from pancreatic flukes of bovines were examined using air-drying techniques. Detailed karyological analyses on somatic cells with 26 chromosomes demonstrated the existence of two different karyotypes in these flukes. In conventional Giemsa preparations, two (Nos. 5 and 7) of 13 pairs of homologs showed a significant variance of morphology between flukes designated Types I and II by size. Additional differences were demonstrated by the C-banding method. The C-banded pattern in Nos. 3 and 8 of each karyotype was different, thereby indicating a different distribution of constitutive heterochromatin on these chromosomes. Among flukes recovered from seven cattle, 76.7% of the flukes were Type I (smaller) and 23.3% were Type II (larger). Obvious phenotypic variance between Types I and II was seen in the taxonomic characteristics such as body size, comparative size of the ventral to the oral sucker, and the egg size. Considering the variance of both types, as based on the statistical data of these characteristics and on comparable published data, at least two species of flukes can be found in the Japanese bovine pancreas. These were Eurytrema coelomaticum for Type I and E. pancreaticum for Type II, respectively.