Oryctes rhinoceros, Linnaeus, 1758

Oryctes rhinoceros View in CoL : 18,neoXY ( Fig. 2C View FIG )

Published data: Yadav et al. (1979) and Dasgupta (1977) reported a 20,XYp formula, but no chromosome description.However, we found this karyotype with 18 chromosomes quite original, compared to others. Pairs nos 1 and 2 are sub-metacentric, and all other autosomes are acrocentric (a single euchromatic arm), but look more or less submetacentric by the addition of large and variable heterochromatic fragments on their short arms. A large portion of the sub-metacentric X and acrocentric Y undergo synapsis at the pachytene stage and chiasma at the metaphase I of meiosis (not shown) demonstrating its autosomal origin and that the neo-sex chromosomes derive from an X-Y-autosome translocation. This karyotype, close to that of Oryctes nasicornis Linnaeus, 1758 ( Dutrillaux & Dutrillaux 2009a), only differs from it (neglecting heterochromatin variations) by the inversion of pair no. 8, which is metacentric in O. nasicornis . NOR location: small autosome (no. 6).