The Clonopsis gallica puzzle: Mendelian species, polyploid parthenogens with karyotype re-diploidisation and clonal androgens in Moroccan stick insects.

The stick insect Clonopsis gallica is a morphologically stable obligate parthenogen, ranging from North Africa to Southern Europe, with a variable karyotype (54-57 chromosomes), considered diploid or triploid. C. gallica origin and relationships with C. algerica and C. maroccana remained unknown. Our Moroccan samples shared the same egg and body patterns and, in addition to a C. maroccana female (2n=22, XX), produced the new bisexual Clonopsis sp. 1 (2n=35/36, X0/XX), C. gallica (2n=54, XX) and the new all-female Clonopsis sp. 2 (2n=72, XX), appearently forming a numerically polyploid series with re-diplodised karyotypes; C. gallica could thus be a triploid hybrid in origin. Furthermore, two strains of ameiotic males with 2n=35 (X0) or 53 (X0) were found, which would maintain themselves as clonal androgens. We could conclude that in stick insects body and karyotype “phenotypes” are considerably independent, thus preventing a sound taxonomy. The high heterozygosity of phasmid hybrids allows parthenogens to persist for long, particularly when polyploids are produced, since backcrosses of the hybrids to the parental species allow the incorporation of genetically diversified genomes. The distribution range of Clonopsis parthenogens appears to realize a sound instance of geographic parthenogenesis.