On the occurrence and identity of triploids of Rana kl. esculenta Linnaeus and R. lessonae Camerano in The Netherlands (Anura: Ranidae)

According to electrophoresis and erythrocyte size the genotypes of 756 waterfrogs, collected during 1986—1988 in 54 localities in The Netherlands, were classified as belonging to 5 different genotypes: 331 diploid R. lessonae (LL), 5 triploid R. lessonae (LLL), 250 diploid R. kl. esculenta (LR), 133 triploid R. kl. esculenta (LLR), and 37 diploid R. ridibunda (RR). The occurrence of triploid R. kl. esculenta in The Netherlands is reported for the first time and triploid R. lessonae has not yet been reported previously. There are indications that LL gametes could be produced by LLR triploids and LL diploids. R. kl. esculenta in R. kl. esculenta and R. ridibunda — R. kl. esculenta populations of the western regions seems to be exclusively triploid, whereas the percentage of triploid R. kl. esculenta in R. lessonae — R. kl. esculenta populations of the eastern regions is about 1%. Biometrical differences were neither found between R. kl. esculenta triploid and diploid, nor between R. lessonae triploid and diploid.