Chromosomes of Prodidominae (Dionycha). Theuma sp. (2n♂ = 28, X1X20) A mitotic metaphase B early pachytene with positively heteropycnotic X1X2 C diakinesis, note a difference in size of sex chromosomes D half of late metaphase II with sex chromosomes. Prodidomus simoni (2n♂ = 29, X1X2X30) E mitotic metaphase F pachytene note positively heteropycnotic X1X2X3 G metaphase I H early metaphase II, note positively heteropycnotic sex chromosomes. Arrowheads indicate sex chromosomes. Scale bars: 5 μm.