Morphometric correlates of karyotype and host plant in genus Euceraphis (Hemiptera: Aphididae)

Abstract Samples of birch‐ and alder‐feeding aphids of genus Euceraphis were measured and analysed using multiple discriminant analysis (canonical variates) to find out if morphological variation correlated with previously reported differences of karyotype and host association. The dataset comprised groups of specimens defined solely by locality and collection date. Mean scores on the first two canonical variates clustered the samples fully in accordance with their karyotypes and host plants, confirming the existence of a number of morphologically similar but distinct host‐specific taxa within the E. betulae group. Three new species are described: Euceraphis borealis Blackman, sp.n. on Betula glandulosa and B. nana, Euceraphis papyrifericola Blackman, sp.n. on B. papyrifera, and Euceraphis quednaui Blackman, sp.n. on B. occidentalis. A key is provided to alate viviparae of the genus.