TETRAPLOIDS OF THE LUNG FLUKE PARAGONIMUS-WESTERMANI FOUND IN CHINA

Two groups of Paragonimus westermani (Tematoda: Platyhelminthes) exist in nature: diploids and triploids. Generally, these two groups live a llopatrically, but in Kuandian, Liaoning Province, in the Republic of China, they live sympatrically. In our Chinese experiment on Paragonim us we used metacercariae of P. westermani, which we collected in Kuand ian, Xigutai, and performed a cytological analysis. The results were a s follows: (1) the P. westermani in Xigutai lived sympatrically as dip loids and triploids; (2) all of the small metacercariae were diploids; (3) the large metacercariae were in large proportion triploids; (4) w e found one tetraploid specimen in both the medium and the large metac ercariae - this was the first time tetraploid lung flukes were discove red; (5) the somatic chromosomes of the tetraploids were different in numbers (4n=44), but we could not find any difference in the karyotype of haploid sets and that of the diploids and the triploids; (6) unlik e the triploids, during their meiosis the tetraploids produced a chrom osome pairing, and we found a tendency of the large chromosomes to bec ome quadrivalent; and (7) also unlike the triploids, a great number of spermatids were found in the tetraploid testes. Because of these find ings, we can consider tetraploids to be autotetraploids, and these are probably produced by the fertilization of diploids and triploids. We also think that the gametes of tetraploids have a fertilization capabi lity.