Phylogeny and higher classification of the cerambycid subfamily Lepturinae remain controversial. Here we report the results of a cytogenetic study of 18 species currently classified in Lepturini and 12 species in other tribes of Lepturinae (1 in Oxymirini, 1 in Rhamnusiini and 10 in Rhagiini) from Western Europe. The male sex chromosome formula is XY in all Rhagiini, Oxymirini and in Grammoptera ruficornis in the Lepturini (whose tribal placement may be doubtful), and X0 in all the remaining Lepturini. The rarity of the X0 formula in other Cerambycidae indicates that the Y chromosome was lost in a common ancestor of the Lepturini or a subgroup thereof, indicating its monophyletic origin. The number of chromosomes is stable in the Lepturini that lack a Y chromosome (19,X/20,XX in males and females, respectively), but varies from 20 to 24 in the remaining genera, probably the consequence of evolution by chromosome fission. Whereas all the males with 19 or 20 chromosomes have an early gametogenesis, which is achieved before the imago stage, the species with more than 20 chromosomes seem to have a delayed male gametogenesis, which is still active in the young imagoes. The species of Rhagiini with 22 chromosomes may constitute a monophyletic group.
Karyotypes of the polyploid parthenogenetic species Saga pedo from four localities in France and the Republic of Macedonia were constructed and compared. All these karyotypes consist of 70 chromosomes, which is more than twice that in other species of the genus. The chromosomes differ from each other, making the matching of homologues difficult. Karyotypes of French specimens are similar, except for differences in the heterochromatin. Compared to that of the Macedonian specimens those from French specimens differ by the shortening of a single chromosome. The difficulty experienced in identifying tetrads and even pairs of chromosomes indicates that either many chromosome rearrangements have occurred since the polyploidisation event(s) or that the addition of quite different genomes is the cause. On the other hand, that the karyotypes are similar indicates a common origin of both the Macedonian and French populations. Thus, most chromosome changes preceded the separation from their common ancestor. Both the DNA content and chromosome analyses suggest that the S. pedo karyotype is pentaploid and not tetraploid as previously proposed. This odd ploidy number rules out the hypothesis that it could only have originated by endoreduplication. It is more likely that it originated by the association of five copies of the 14,X haploid karyotype, which exists in the gametes of the closely related species, S. campbelli and S. rammei (male / female 2n = 27, X / 28, XX). Fertilization of a parthenogenetic 56, XXXX female by a 14, X spermatozoa could have resulted in the last increase in ploidy.