The incompatible results of mating experiments (Hebert
1971, Yaegashi & Udagawa 1978, Kato et al. 2000) have made it more difficult to
resolve the taxonomic problem. Nevertheless, molecular analyses (Borromeo et
al. 1993, Kato et al. 2000) have provided evidence for genetic separation of the
two taxa. A significant contribution to the taxonomic resolution came from the
multilocus genealogical approach of Couch & Kohn (2002), although to some