No abstract

Five sympatric colour varieties of the hoplonemertean Tetrastemma nigrifrons (var. pallidum, var. bicolor, var. purpureum, var. punctata, var. albino) were found in Vostok Bay (the Sea of Japan) . The taxonomic status of the varieties, some of which have been known for almost a century, was uncertain . Starch gel electrophoresis was used to compare allele frequencies of these varieties at 19 isozyme loci . Neither fixed allelic differences nor statistically significant differences in allele frequencies between different colour varieties was revealed . It was concluded therefore that all the colour varieties studied are conspecific . As estimated from the electrophoretic screening of 24 isozyme loci, the species is highly variable at the molecular level . It has high mean values of observed and expected heterozygosity estimates, H o = 0 .313 ± 0 .049 and He = 0 .323 ± 0.050, and is one of the most variable species among invertebrates .