GENETIC-DIVERGENCE OF ASIATIC BDELLOCEPHALA (TURBELLARIA, TRICLADIDA,PALUDICOLA) AS REVEALED BY PARTIAL 18S RIBOSOMAL-RNA GENE SEQUENCE COMPARISONS

Polymerase chain reaction (PCR)and direct sequencing of small ribosoma l RNA genes were used for analysis of genetic differences among Asiati c species of freshwater triclad genus Bdellocephala. Representatives o f four species and four subspecies of this genus were used to establis h homology between nucleotides in the 5'-end portion of small ribosoma l RNA gene sequences. Within 552 nucleotide sites of aligned sequences compared, six variable base positions were discovered, dividing Bdell ocephala into five different genotypes. Sequence data allow to disting uish two groups of these genotypes. One of them unites species from Ka mchatka and Japan, another one unites Baikalian taxa. Agreement betwee n available morphological, cytological and sequence data is discussed.