Cassida humeralis: 1 spermatogonial metaphase with 2n = 18 meta/submetacentric chromosomes, the small X-chromosome is arrowheaded and the tiny y-chromosome pointed by an arrow 2 meiotic diakinesis with a 8 + Xyp meioformula, the Xyp is arrowheaded 3 meiotic metaphase II of X-chromosome (arrowheaded) class with nine chromosomes 4 meiotic metaphase II of y-chromosome (arrowed) class with nine chromosomes.