Chromosomal confirmation of the separate species status of Melanotus villosus (Geoffroy in Fourcroy, 1785) and M. castanipes (Paykull, 1800) (Coleoptera, Elateridae)

Karyotypes, with C-banding, are given for Melanotus villosus (Geoffroy in Fourcroy) and M. castanipes (Paykull). The preparations are from mid-gut and gonads of adults, and mid-gut and testis of larvae. M. villosus has 2n = 18 + X (♂), 18 + XX (♀), while M. castanipes has 2n = 20 + X (♂), 20 + XX (♀). The X chromosome of M. villosus is the smallest in the nucleus, while in M. castanipes it is among the largest. Heterochromatin is confined to small centromeric C-bands in both species. The differences between the karyotypes of the two species in both total number chromosomes present and in particular the size of their X chromosomes are sufficient to confirm that two distinct species are involved.