Meiotic chromosome preparation was performed from testes of P. schultei according to standard protocols. Males were injected with 0.1 mL of 0.1% colchicine in double-distilled water for 1.5–2.0 h prior to fixation of testes in ethanol:glacial acetic acid (3:1) for 15 min, and then kept in 70% ethanol. Air-dried chromosome preparations were obtained by squashing testis follicles in 45% acetic acid and then freezing them on dry ice.