Multivariate morphometrics of two Podisma species (Orthoptera : Acrididae)in Kunashiri Island

We examined morphological variation in Kunashiri populations of P. sapporen sis Shiraki and P. tyatiensis Bugrov using multivariate morphometrics to cl arify their taxonomic status in comparison with Hokkaido populations of P. sapporensis. Although P. sapporensis in Kunashiri Island has a unique karyo typic characteristic, the neo-X and neo-Y system, cluster analysis indicate d that the morphology is included in the range of variation seen in Hokkaid o populations with the XO-male determination system. P. tyatiensis is chara cterized by having short-armed chromosomes compared with other Podisma spec ies, but the morphology of this species did not differed much from P. sappo rensis in Hokkaido, either. These results suggest that chromosomal changes do not contribute to phenotypic diversification. P. sapporensis in Kunashir i Island is probably reproductively isolated from P. tyatiensis on the same island because of conspicuous differences in the karyotype, whereas it is highly probable that P. tyatiensis in Kunashiri Island and P. sapporensis i n Hokkaido constitute the same biological species.